Same Newb-Different question! Ignition Switch - Page 4 - Diesel Forum - TheDieselStop.com
7.3L IDI Diesels (Not Power Strokes) Technical discussion of topics related to vehicles powered by the 7.3 Liter In-Direct Injection Navistar engines.

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post #46 of 73 (permalink) Old 12-24-2017, 04:32 PM
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Tie the "hot" wire to the Starter energise wire inside the cab. That eliminates the switch, if the starter turns, then the trouble is the switch. If it doesn't, then make all of your checks again with the two wires tied together, and find where the trouble lies. It aint rocket science. Improvise, that is what DIY is all about. This is going to boil down to "What have the mice, and packrats done to the wires?". You might be running temporary wires to the run components, so that you can get it home where you can actualy work on it. Remember, switches are nothing more than a fancy way to hook two wires together. Look for the obvious, chew marks on the wire harnesses, broken spots, things that are likely to be causing your troubles.

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post #47 of 73 (permalink) Old 12-24-2017, 05:57 PM Thread Starter
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That's why ALL the truck's details need to be in your SIGNATURE, so they appear with each of your posts automatically.

Okay, scolding taken. This goes back to the "When I first joined and wasn't able to post pics" era-when I was going to fill out my info, it wouldn't let me post a pic of the truck, which someone had requested, so I thought I would wait until I could. NOW, I tend to want to spend all of my time on here trying to research and fix my problem, so taking the time to fill out the signature has not been a priority. I am sorry if that has been a hindrance!

Also, another warning: I currently have 24 cars, trucks, vans, RV's, and 3 motorcycles. Many of these end up being "duplicate" vehicles, where once I find something I like, I buy multiples. So I might end up with 5 very similar versions of this, and you STILL won't know what I am talking about, but...

On the issue at hand-family took me away from much testing today, but when I had a few minutes I ran down to the truck, got out the new Multimeter and ran it to the key switch again. OFF, ACC: 12.6 V or so. RUN: 0.5 V or so. Went back to GPR (+) cable post to check, as it is about a halfway point. OFF, ACC: 12.6 or so, RUN: 0.5 or so (I think, but significantly lower is the point-don't remember exact reading. Went down to starter real quick. At (+) post on starter, again, OFF, ACC: 12.6 or so, RUN: 0.5 or so. So, from this info, it would seem that my problem is indeed between the (+) post on the battery, and the (+) post on the starter, correct?

Thanks! Will TRY to get on and put details on my signature/profile.
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post #48 of 73 (permalink) Old 12-25-2017, 09:51 AM
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Pot, kettle, black??
When I get a 7.3L, and I have questions about it, I'll put its details in my sig. I didn't think anyone here would care about my Broncos or my CV, so they're not listed. If you are interested, click my sig.
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If your using the autoguide app on a smart phone, signature DOESNT show.
I don't use it, for that & several other reasons. So I can see that his sig is empty.
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... taking the time to fill out the signature has not been a priority.
It would have taken less time to fill in your sig than to explain why you haven't.

We don't need to know about all 20 of your vehicles - only the ones with 7.3s that you'll be asking about here. And if there are several 7.3s in your sig, when you ask about one, be sure to ID it.
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So, from this info, it would seem that my problem is indeed between the (+) post on the battery, and the (+) post on the starter, correct?
It's hard to say because it's so random. If you use the methodical process I described, you won't need us to confirm your guess; you'll KNOW where the problem is when you find it.


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post #49 of 73 (permalink) Old 12-25-2017, 10:31 AM
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Good for you!! Some of us donít sit around looking at a desktop or laptop. To each their own.

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post #50 of 73 (permalink) Old 12-25-2017, 09:22 PM Thread Starter
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Originally Posted by jmshawii View Post
So, from this info, it would seem that my problem is indeed between the (+) post on the battery, and the (+) post on the starter, correct?

It's hard to say because it's so random. If you use the methodical process I described, you won't need us to confirm your guess; you'll KNOW where the problem is when you find it.
Steve83, I have to say, I am REALLY sorry that I am not living up to your personal standards here, and I tried to explain that I have NOT HAD TIME to do your methodical process YET, but had time to test a couple of places that were EASY and QUICK to get to, JUST to see if I was getting readings, if they made sense, if I seemed to be able to work the MM properly, if the MM was working properly, etc.

However, in doing this, I DID get a reading that provided some information, that SEEMED right in line with your methodical process, and thus, I thought I would throw it out there. You seem to want me to do these readings every 2 feet or so and between every possible juncture of metal/conductor/electrical current. I UNDERSTAND that this is advisable, and agree this is ideal WHEN I HAVE MORE THAN 5 MINUTES at a time. Again, I was JUST playing around and experimenting, but basically, instead of testing every 2 feet or possible connection, I was able to very easily test a stretch of about 8 feet. I got a reading which is what, TO MY UNDERSTANDING, is what you have asked me to watch for. You said when I found the noteable drop in voltage under the conditions that cause the problem, I will have found the location of my problem. I did just this, asked if that meant I had found the stretch of current with a break, and thus, my problem, and you say it is a random finding and is inconclusive.

So, if you could, PLEASE pick me apart further, call me an idiot, lecture me some more, and explain to me WHY this is not good information, i.e. why it does not help to show that the problem may be somewhere between the most distant points that could be involved in this finding under these testing conditions. Your answer basically says that though I now know that I lose massive voltage between the positive posts of the batteries and the (+) cable post on the starter, that the problem is not necessarily in that section of the system. Is that not exactly what I am testing for?

I just would really like to understand what I am doing here. I thought I understood what I was looking for, and if this is not it, please let me know. I don't care if you pick me apart, call me an idiot and criticize my personal communication style if you are helping me, so feel free and enjoy, but please help me understand what I am looking for. I now do not feel like I can do your methodical test, because how I was planning to go about it no longer sounds like what I thought it did.

Thanks!

P.S. See Signature for truck in question!

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1988 International Harvester S1654 Retired UHaul truck
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IDI 7.3 International Diesel, 5-Speed

1989 F-350 XLT Lariat, CC, DRW, 2WD
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post #51 of 73 (permalink) Old 12-26-2017, 07:14 AM
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jmshawii, well said, couldn't agree more. No offense, but you might have avoided a hassle at the start if you had followed the advice from a couple of us with real world experience that actually own 7.3's and have worked on IH trucks,etc, for a living. Once again, as Chuckster and I suggested, start at the switch and proceed back towards the battery. It's impossible to diagnose your problem by staring at a monitor, but IF your IH truck is like most all the larger models there's a very strong possibility that your problem is right at the large harness plug at the firewall. They are subject to corrosion after a period of time. You won't find an IH truck plug anywhere in a "bronco wiring schematic". Hope this helps.

Also, who knows if U-Haul spec'ed their trucks out different than "normal" Internationals. At one shop I worked in, we had the repair contract for the local U-Haul franchise and even they're gas engine powered trucks had engine RPM governors so they couldn't be overwound.

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post #52 of 73 (permalink) Old 12-26-2017, 09:31 AM Thread Starter
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Okay, LMJD-but I had to take somebody's advice, and one said start at the battery and the other said start at the switch. It was basically a coin flip/timing issue. So I started at the battery. No offense intended.

Biggest problem with trying to test back this way is, as I said, trying to actually trace the wires up under the dash after they leave the ignition switch. Is this supposed to be possible?

Ground wire to GRD post on ignition switch? No need for it?

Bad juice to starter under symptomatic conditions? Still test farther up the line? Still turn around and start testing from the ignition switch back? Doesn't all the juice going up to the ignition switch that I would be testing for come from here initially? SO if the symptoms exist here (at the starter), under the exact same conditions as they do at the ignition switch, is there any reason to test on up at the switch?

Or is it possible a bad switch could short out the whole system (this was a question I asked a LONG time ago and never got an answer on-so still curious), causing a HUGE dip in electric all the way back to the starter?

IF the "run a hot wire directly from the starter back to the dash ignition switch" is a good idea, which post do I want to run it to on the switch?

J. M. Shaw, II, D.C.
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post #53 of 73 (permalink) Old 12-26-2017, 10:55 AM
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No offense taken. The reason for the ground wire on the switch is every once in a while you run into a component that has an always hot wire going to it and the circuit is completed only when it grounds through the ignition switch. Providing you DO have the plug at the firewall, I'd turn on the key to the start position (helper needed) then stand on your head or whatever it takes to see if you have juice at the plug under the dash. Then see if you have juice at the same terminals on the engine side.
Sounds like you have the switch that each wire is screwed onto the back of it individually rather than the plug in type? If so, are you SURE the wire that energizes the starter relay is hooked to the "start" terminal on the back of the switch? Another thing, in the pickups with a 7.3, there's a starter relay on the right fender under hood panel that in turn energizes the starter-mounted relay (solenoid). Don't know if you have that or not. The IH trucks I worked on had every engine but a 7.3.

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post #54 of 73 (permalink) Old 12-26-2017, 05:04 PM Thread Starter
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No, the starter switch is plug-in type on the back. 11 "posts/blades/terminals." I think the ones with the screw in posts usually have only 4 posts, maybe. You tell me what to call the connectors on this switch and I will call them that! One large plug from under dash loom that has 6(-ish) female slot attachment spaces for the blades on the back of the starter switch to go into. I currently only have 1 individual wire going to the 4 blade metal square attachment set that is the ACC attachment, and 2 separate, individual wires to the other side of the switch to the 4 blade metal square attachment. As previously stated (by you?), all the wires are basic black.

I have the key switch hanging down under the dash right now. No longer screwed into the dash. Of possible note: these problems started/happened while the switch was in the dash. Upon removing it, I have paid attention to where the wires are going, was careful not to tear any loose or break any. I also mention this because I was curious of the dash was the ground for the switch, and thus, the lack of a ground wire attached to the GRD blade on the switch. However, I have tried attaching a ground wire to that post and saw no differences.

I just went through the fuse box AGAIN, and both inspected and tested the fuses. Actually, I tested and inspected all of the modern plastic blade style fuses. There are 4-5 of the old, larger, metal guys in there that I never even knew if they were considered fuses or not! Should I? Are those things just fuses?

So, I'll recap a bit of what I have found on the key switch end:

1.) All fuses that I tested are all good, in appearance, continuity, and resistance. I did start and drive the truck several times when test driving and buying it, driving it home, and tinkering around after getting it home. I drove it over 100 miles home from the place of purchase, on small, country roads and moving relatively slowly, so took about 2.5 hours all together with a couple of stops to check things out. All systems were working that I tried.

2.) it went completely key dead on me once, and I STARTED this thread, then replaced a fuse and it worked-for about 24 hours and 5-6 starts. Then, turned key, thought I heard a small click from under the dash and all dash functions and starting functions went dead. Headlights also are not working. Last time, when it ended up being just a fuse, headlights still worked.

3.) Checked the fuse again, but no problem. Key works in ACC, not in RUN or START positions.

4.) Key gets constant electric on main wire to switch when OFF and in ACC, but goes DEAD when turned to RUN and to START (per test light).

5.) Hooked up the voltmeter to the switch. At main ignition switch blade that receives the CONSTANT electric wire, when in OFF and ACC key positions, WAS getting 12+ volts to the switch. When key is in RUN or START, Voltage goes WAY down-to 2-5 Volts. This, again, is the CONSTANT on juice/electric wire/terminal on the ignition/key switch.

6.) After testing for a while. something changed. I started trying to run my test light to different wires and trying to see if I could get juice/light anywhere else. In doing so, I one time touched the tester to the wire on the ACC side of the switch while I had the clamp end of the tester on one of the independent wires on the far side of the switch from the ACC side, and heard a quick buzzer sound (comes on when car is in RUN, or ACC, when things are working normally) which quickly went dead. This buzzer was no longer working when the switch was in RUN since this trouble started, but was still on very steadily when the key was in the ACC position. After this quick touch of the tester wires between these two wires, and fthe buzzer sound, the buzzer now comes on for a short period when the key is in ACC, but then goes off. The full-time power to the hot wire is still good in OFF, but is now decreased considerably when in ACC. This also was just before testing the fuse for the horn. I had put the key in the ACC position and tested the horn, which let out a weak bleat with the engine off but the key in ACC. After this testing of the two wires NOT in the main plug going to the starter switch, I have no reaction when pressing the horn, despite the fact that the fuse looks and tests out fine.
As I said, the voltage to the switch seems affected now, too. It still tests full 12(+) at the key switch in off, but now, when shifting into ACC, it drops to very low-anywhere from below 1.0 V, to below 6.0 V. When I switch back to OFF, the Voltage goes back up to normal (12.5-12.64 or so), but when switched to ACC it drops very low again, and stays here until turned back to OFF, where it will return to full. It still gets no/minimal voltage in RUN and START.

7. I have NO assistant, nor hopes to have one while staying here, which is basically until I get the truck running, and I do not speak exaggerate. I am traveling, in a place where I know very few people, none well, and am staying with family that left yesterday to go out of town for 5 days. I am SUPPOSED to leave the morning they return, so will have no one here to help me with turning the key switch the whole time. So ever saying "Have someone turn the key to run for you" is simply not something that happens until I hire someone to fix this, and they usually don't want you to stick around and watch and try to see what they are doing, but I WANT to LEARN how to diagnose and fix this!

8. I DID try running the tester from the hot wire to the other posts on the key switch to "jump" the juice to whichever one triggers the starter, but got no reaction from either one. I only thought this may work because I had triggered accidentally cranking of the starter with a test wire bridging a circuit in this manner before, so assumed it would work. I can try doing this more directly with a wire dedicated to do this, but, again, the involvement of the headlights makes me doubt this is the REAL issue with the lights and the dash lights, etc.

One of the first things I did was buy a new switch, but upon doing some research, I decided to see if that should be it. Since, I have not put the new switch in, as everyone seems to be telling me it is something else. However, the fact that the symptoms have now changed, again, based upon movement of the key switch, I am tempted to just try the new switch and see if that helps. If it weren't for the headlights now not working, I would still think this could be it, but somewhere in my searching before starting this thread, someone mentioned that the headlights do not have ANY association with the headlight switch, so there should be no correlation, and that must mean it is NOT the switch. Also, I didn;t want to risk hooking it up, and whatever is wrong causing trouble with the new switch, so I didn't do it yet. However, again, I am very tempted now-especially since I finally got an answer about the ground wire. Aside from the ground wire, I am sure the wires I have on it are the ones under which it was functional before, so it shouldn't cause a "meltdown" with the switch. And the fact that the switch has changed how it treats the power to it, I am now back to thinking that may be the problem-or at least part of it.

As for your solenoid suggestion, from what I saw on-line, there are 4 solenoids between the batteries and the ignition switch. I think I have found 3 of them, but have not tested any of them, as it has not been a strong recommendation as of yet. I know that of the 3 I have checked the "in" feed to them, they are getting power that far. Now that I have the digital MM with couple foot long leads, I can likely check them with the leads attached, and the display somewhere I can see it. Should I just check what the "output" post on each of these does when I turn the key?

Also, again, would this affect the headlights?

Thanks!

J. M. Shaw, II, D.C.
1988 International Harvester S1654 Retired UHaul truck
(Converted to Flatbed Hauler-ish)
IDI 7.3 International Diesel, 5-Speed

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post #55 of 73 (permalink) Old 12-26-2017, 07:23 PM
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...I am REALLY sorry that I am not living up to your personal standards here...
Well, you should stop worrying about me, and focus on diagnosing your truck. That's what I'm focused on.
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You seem to want me to do these readings every 2 feet or so...
No, I've said repeatedly that there is no set increment. In some places, I'd go about a millimeter from a cable eye to the nut clamping on the starter relay stud; in other places, I'd go 3' from one end of a cable to the other. But you can do it however you like. If you follow the instructions I posted originally, you WILL find the fault relatively quickly.
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So, if you could, PLEASE pick me apart further, call me an idiot, lecture me some more...
No, thanks. That's not why I'm here. But to answer YOUR questions accurately, I need some specific info. I've asked you for it politely several times now. IDK why you're getting bent out of shape about it. You're the one being difficult.
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...explain to me WHY this is not good information...
That would be a bigger sidetrack than we're already on, and it would only slow down this process.
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Your answer basically says that...the problem is not necessarily in that section of the system.
No, you misread it. It says "I can't follow what you're describing." Maybe some of the other participants in this thread can. I've been fixing electrical faults on vehicles of all makes, models, & FUELs since high-school, and what I suggested will work on all of them. Boats & airplanes, too.

Now, if someone tells you that MANY trucks similar to yours have a particular electrical fault that can produce the symptoms you see, and you check yours & find it has that fault - yes, you'd save yourself some time. But if it DOESN'T, then you'll be back to the procedure I suggested because it ALWAYS works (when you follow it).
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...please help me understand what I am looking for.
Exactly what I said originally. It's still there, so there's no reason for me to re-type it all. If there's something specific that you don't understand, let me know what it is, & I'll try to clarify.
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Or is it possible a bad switch could short out the whole system (this was a question I asked a LONG time ago and never got an answer on-so still curious), causing a HUGE dip in electric all the way back to the starter?
Not in the way you think. If the ig.sw. was bad enough to do something like that, it would burn a fuse or a fusible link. It can't stop the battery from producing voltage, and there is no fuse between the battery & starter.
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IF the "run a hot wire directly from the starter back to the dash ignition switch" is a good idea...
It's not, at this point in the diagnosis. There are only a few things that might happen...
1) Nothing: which tells you nothing, and you've wasted your time.
2) The overlaid wire catches fire: which tells you there's a serious short to ground in a B+ circuit, but it doesn't tell you WHERE. And you have burning insulation dripping off the wire onto the floor of the truck, and the paint, and your work area...
3) All the symptoms disappear (at least initially): which tells you there's an open (break) in a B+ circuit, but it doesn't tell you WHERE. To find that location, you'd have to follow the procedure I suggested. If you attempted to operate the truck with the overlay, you'd run a serious risk of it catching fire at any moment, because you don't know for sure if it can handle the current that could pass through it as you operate all the normal circuits on the truck.
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...which post do I want to run it to on the switch?
Any terminal that ever receives +12V would be OK. But for a chance at a diagnosable result, you'd probably want to start with one that SHOULD have constant B+, but doesn't.

I'm just getting to your 5:04 post, but it's getting late, so I'll try to read it Wed.

BTW
If you don't find my posts helpful, just say so. No drama required. I'm only replying to you because you seem to be interested in what I post. If you're not, I'll quit posting in this thread. If you (or anyone else) don't want to even see my posts any more, just add my username to your IGNORE list, and they'll all be blanked out automatically for you by the forum software. It's as easy to do as it is to UNdo, in case you just want to see what it looks like.


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post #56 of 73 (permalink) Old 12-27-2017, 07:56 AM Thread Starter
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Steve83:

No problems here. I'm a smartass, and sarcastic, and not bent out of shape at all. I am sorry that you think that I am being difficult.

You and I communicate very differently. I have recognized that and am fine with that. When I say I am fine with how I perceive your writing and comments, I MEAN it-as long as I feel you are trying to help, which I feel you are. Please, by all means, keep the info coming. I will read it, see what I can understand, try it and see how it works. I will post what I find as well as I can. I will take any help, recommendations, and suggestions I can get.

So, let me try to state this more simply:

I have good Voltage (12.64, I think) at the batteries. I have good voltage (the same) at the starter with the key OFF or in ACC. When I turn the key ON to RUN or to START I have a MASSIVE drop in voltage AT THE STARTER (Less than half at least, maybe a LARGER drop-I don't have my notes right here with me). With those 2 testing points showing these results, does this indicate that my problem is PROBABLY somewhere between my battery and the post on the starter?

This is how I thought you requested I test (Specific Point to Specific Point, when I see the massive voltage drop, under the conditions that cause the symptoms, I know the problem is in that segment). I am not FINISHED testing this stretch (YES, I KNOW, EVERY connection point needs to be tested), but that is a reading I got and what I was asking is if this did indeed tell us ANYTHING.

Input? From anyone?

Thanks!

J. M. Shaw, II, D.C.
1988 International Harvester S1654 Retired UHaul truck
(Converted to Flatbed Hauler-ish)
IDI 7.3 International Diesel, 5-Speed

1989 F-350 XLT Lariat, CC, DRW, 2WD
IDI 7.3, Auto, Charity Auction Find!
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post #57 of 73 (permalink) Old 12-27-2017, 12:32 PM
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From the pass side battery negative post you should have a small ground wire to the chassis and a larger wire to the engine, on a 7.3 it's bolted to the front of the engine. The connection gets rusted and corroded. Clean it.
Since I asked that question, I see that you have done that.
I was hospitalized from 12/1 to 12/25 so I couldn't answer any question during that time.
When you turn the "KEY" to RUN and have a "massive" voltage drop, something that is trying to Energize is shorted to ground, In the case of the starter, it may be that it is defective, may not be shorted but not be able to rotate, that will cause a "massive" voltage drop, DISCONNECT THE WIRE ON THE STARTER, see if that solves the "Massive" voltage drop, that starter pulls 600 amps trying to start that engine, also there is only three other places that are energizing are the "HI Cold IDLE Solenoid" and the IP "FSS Fuel Shutoff Solenoid" and the "Cold Advance Solenoid" you can eliminate them by disconnecting the Cold head coolant Sensor located on the pass side head under the Alternator, the third place is the Glow Plug Controller, disconnect the battery wire on the GP relay also the wire from the key switch. Disconnect each place one at a time, then try Key RUN.
Those Silver "things" plugged into the fuse panel are "Circuit Breakers", you could pull all of them out, if that solves the voltage problem, replace one at a time.
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92 F350 Lariat, 2WD, Dualie, CC, LB, E4OD Trans, Banks Sidewinder turbo, GV O/U, Pyro, Boost, Oil temp, Trans temp. Chassis 129K, Engine 7.3L 75K. Bench seat.

"99.5 F350 7.3 PSD 4R100 CC LB 4X4 DRW 4:10 Centurion Conv.
ScanGaugeII SPDiesel Performance Module 40-60-80 HP -- A Pillar - Boost - Pyrometer - Trans.Temp. - Engine Oil Temp.GN Hitch 20K -- Reese 16K 5er Hitch - Draw Tite Brake Control - Aux. Trans. oil cooler - 100 Gal. Transfer Flow fuel tank, W/Trax II computer. DIY black bed liner. Red Knight

IDI firing order 12734568--------1&4-2&5-7&6-3&8 Cyl's @ TDC. 1&4 TDC when timing mark is @ 0. Each 1/4 turn, next 2.

Last edited by Trucker87; 12-27-2017 at 12:43 PM.
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post #58 of 73 (permalink) Old 12-27-2017, 03:10 PM Thread Starter
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Quote:
Originally Posted by Trucker87 View Post
Since I asked that question, I see that you have done that.
I was hospitalized from 12/1 to 12/25 so I couldn't answer any question during that time.
Hey! Sorry to hear that! Hope everything is better!

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Originally Posted by Trucker87 View Post
When you turn the "KEY" to RUN and have a "massive" voltage drop, something that is trying to Energize is shorted to ground, In the case of the starter, it may be that it is defective, may not be shorted but not be able to rotate, that will cause a "massive" voltage drop, DISCONNECT THE WIRE ON THE STARTER, see if that solves the "Massive" voltage drop, that starter pulls 600 amps trying to start that engine, also there is only three other places that are energizing are the "HI Cold IDLE Solenoid" and the IP "FSS Fuel Shutoff Solenoid" and the "Cold Advance Solenoid" you can eliminate them by disconnecting the Cold head coolant Sensor located on the pass side head under the Alternator, the third place is the Glow Plug Controller, disconnect the battery wire on the GP relay also the wire from the key switch. Disconnect each place one at a time, then try Key RUN.
Thanks for that and the diagram-that is one of the best I've seen yet!

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Originally Posted by Trucker87 View Post
Those Silver "things" plugged into the fuse panel are "Circuit Breakers", you could pull all of them out, if that solves the voltage problem, replace one at a time.
Thanks for that info as well. Never knew if they were "super-fuses" or relays or what! Good to know-especially so I can describe them better to folks trying to help me-like you guys!

Here is an interesting tidbit: On the NEW switch I got, the connection that is labeled "GRD" on the OLD switch, is labeled "ST" on the new one. This inspired me to experiment a bit and move one wire (the thickest black one from the "loom" that goes to the ignition switch multi-connector plug) and move it to the same post on the OLD plug-figuring that if it was the thickest, it was either the ground or the starter wire anyway. Upon doing this, I got the dash lights and warnings to come back to life when I moved the key to RUN, but it killed everything again when I turned the key to START. SO that didn't seem to be the answer. I couldn't get the new switch key to even turn last night, so didn't get to try installing it. After bringing it inside, I sat playing with it while watching TV and eventually it broke loose. So I will try putting on the new switch in a few minutes.

Also, I JUST came in from changing the (-), battery-to-battery cable. Though I could get a good test result from the old cable, I did notice that sometimes the number seemed a little low, as the end was a little corroded. I had wire brush cleaned it where it contacts the posts of the battery, but thought maybe it had internal corrosion that was affecting it as well, so thought it wouldn't hurt to swap that out as well. I could only get a 4 gauge cable, and would have liked a 2, but I don't think that should be enough to render it completely useless, while it is brand new and only running 12" from battery to battery.

Also, along your earlier suggestion, the ground cable from my batteries is one of those thick, old, metal braided straps. It goes to the frame right by the battery box. There is one, small wire that also connects to one battery, but I traced it to up inside the cab to the old trailer brake controller. So I do not have a ground going to the engine, but I did try running the jumper cable up to the engine bay and to the alternator bracket (testing it for good ground at the time), and left one end on the battery (-) post and the other on the alt bracket. No change in symptoms.

So, that is where I am at at the moment. I'm heading back down to check some things out. I'll let you know what comes out of the next round of testing.

Thanks!

J. M. Shaw, II, D.C.
1988 International Harvester S1654 Retired UHaul truck
(Converted to Flatbed Hauler-ish)
IDI 7.3 International Diesel, 5-Speed

1989 F-350 XLT Lariat, CC, DRW, 2WD
IDI 7.3, Auto, Charity Auction Find!
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post #59 of 73 (permalink) Old 12-27-2017, 03:34 PM Thread Starter
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Quote:
Originally Posted by Trucker87 View Post
When you turn the "KEY" to RUN and have a "massive" voltage drop, something that is trying to Energize is shorted to ground, In the case of the starter, it may be that it is defective, may not be shorted but not be able to rotate, that will cause a "massive" voltage drop, DISCONNECT THE WIRE ON THE STARTER, see if that solves the "Massive" voltage drop
Just realized that I am not clear on this. Are you meaning to disconnect the wire to the SMALL post on the starter? I am guessing not the battery cable to the starter, as then there would be no effect from the use of the ignition switch, which is the stimulus that causes all such problems.

So I am going to go down and try the new ignition switch, then crawl under and disconnect the wire to the small post on the starter and try this test, and then try the cable to the glow plug relay, etc, and see if I find anything. Also going to try removing the small wire from the battery negative terminal also, just in case that is grounding somehow.

Thanks!

J. M. Shaw, II, D.C.
1988 International Harvester S1654 Retired UHaul truck
(Converted to Flatbed Hauler-ish)
IDI 7.3 International Diesel, 5-Speed

1989 F-350 XLT Lariat, CC, DRW, 2WD
IDI 7.3, Auto, Charity Auction Find!
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post #60 of 73 (permalink) Old 12-27-2017, 05:17 PM Thread Starter
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That failed! I put the new key switch on, got life (dash lights, buzzers) in RUN, but upon turning to START, again, everything died and did not come back on when the key was turned back to RUN, or OFF, or ACC, etc. After a few minutes it did-but only in OFF and ACC. Still no life in RUN or START.

Just for the record, with what I am about 90% sure now is the starter wire disconnected from the switch, the readings (when reading at all!-more on that later) are:
OFF: 12.5V
ACC: 12.5V
ON: 0.07V
RUN: 0.07V

So, again, this seems to indicate it is not the switch and not the starter.

On the "reading at all" comment from above: I have noticed the following happening at times, and it seemed VERY bad and VERY obvious this time, so I am pretty sure it is a real thing, not just my ineptitude. After it goes dead, it sometimes does NOT read ANYTHING in any key position for a short period of time (from say, 15 seconds to a minute or two), and this seems to be anywhere along the line-at the starter, the GPR, the (+) posts on the solenoids on the upper driver's side firewall (both outside in the engine bay and inside in the passenger compartment by the fuse box) and at the key switch. When going back to the battery and checking the cables, it seemed VERY difficult to get a positive test light response from the (+) cable. At the terminal was good, the connector was good, but when trying to poke the probe into the cable it was very hard to eventually get a test light to light up.

Along with this, while testing with the test light in many of the locations, the light would waver and flicker, no matter how still and firm I held contact. Thus, I did not feel I could accurately test anything. Though I am obviously trying to learn something and figure this out the right way, I now think I am going to try to replace the (+) cable from the battery to the starter tomorrow and see if that helps, or at least stabilizes the electric supply up the line so I can test more accurately. This is, regrettably, kind of the "throw parts at the problem" approach, but I am really frustrated and need to be sure I have enough electric flowing to test accurately. At times when it is reading DEAD all across the system, I can not discern WHAT makes it start "flowing" with electricity again, and thus, feel there must be something weak in the simple supply from the start.

So, that's the latest. I guess the question is, can I get away with 4 ga cables? Again, I would prefer to get 2 ga, but I am not sure I can get them in this small town. If it helps me diagnose the problem, and hopefully last me about 3 weeks to make the big trip I NEED to take, I don't mind if they melt! But I NEED to get this thing ready to leave and drive 1100 miles by Saturday AM.

J. M. Shaw, II, D.C.
1988 International Harvester S1654 Retired UHaul truck
(Converted to Flatbed Hauler-ish)
IDI 7.3 International Diesel, 5-Speed

1989 F-350 XLT Lariat, CC, DRW, 2WD
IDI 7.3, Auto, Charity Auction Find!

Last edited by jmshawii; 12-28-2017 at 06:59 AM. Reason: Add further explanation
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