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I find it strange that something upstream mysteriously died at the same moment you pulled the starter, but you do seem to have ruled out the new starter and its connections with your jump start of the solenoid.

The usual suspects are the digital transmission range sensor (DTRS) which incorporates the neutral safety switch or the ignition switch itself. The DTRS could be bad internally, or could be out of position secondary to a gear selector position issue. I would first try starting the truck in neutral, then try jiggling the selector a bit while trying to crank. If that doesn't work, get a meter out and see if you are getting power to the DTRS while someone turns the key. Did you have the batteries disconnected when you pulled the starter?

Look for power at pins 10 and 12

View attachment dtrs1.pdf
 

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I find it strange that something upstream mysteriously died at the same moment you pulled the starter, but you do seem to have ruled out the new starter and its connections with your jump start of the solenoid.

The usual suspects are the digital transmission range sensor (DTRS) which incorporates the neutral safety switch or the ignition switch itself. The DTRS could be bad internally, or could be out of position secondary to a gear selector position issue. I would first try starting the truck in neutral, then try jiggling the selector a bit while trying to crank. If that doesn't work, get a meter out and see if you are getting power to the DTRS while someone turns the key. Did you have the batteries disconnected when you pulled the starter?

Look for power at pins 10 and 12

View attachment 111570
Thanks RT - I did have the batteries disconnected, but out of curiosity, if I didn't what would that do/fry?

I'll check the DTRS as you suggested, I already tried starting in park and neutral and pushing the gear shift all the way up into "P" since it does have some play, I also checked the neutral switch to make sure it was lined up, I had to leave it unbolted from the trans to keep it in the neutral position since the actual linkage would basically force the switch out of the neutral position just slightly, I had a no start one time before and I think it was this issue because pushing the shift lever all the way up into "P" it started right up, unfortunately no luck this time. I read also that I can check the small wire on the starter for 12v when turning the key but I think that would be the same as checking the connection by the fender, I think I can rule out my connections on the starter since I can jump it, right? Has to be something upstream doesn't it?
 

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Logic would dictate that if you can apply voltage at that wire and get a response, you should be able to rule out the starter and connections. I would have to go out and look - I don't remember there being more than one wire on the small terminal. On a older model gasser, there were two terminals on the solenoid - one would supply voltage to the coil, the other from the key.
 

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That's what I figured - I literally just came in from testing it again - I put a circuit tester on the female end of the wire connection, which is the feed coming from the dash/ignition - when my wife turned the key I got no light, so no power - which confirms that everything from the connection to the starter should be good since jumping it works fine).

Any idea what all is hooked up here that could cause this? I think all there is that it could be are a fuse, relay, ignition switch, or neutral switch/DTRS (are the DTRS and neutral safety the same thing?)??
 

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The neutral safety switch is incorporated into the DTRS on this transmission. There is a fuse, there is a starter relay, there's a fusible link in there somewhere. Lots to check out.
 

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What you have to do to fix it is start tracing back the start circuit where you didn't get voltage. When you get past a component and get voltage when you turn the key to start, that component is your problem. Be sure to use a logical approach to your troubleshooting, and rule out one thing at a time.

Could be the ignition switch. It has 4 separate switched circuits in it and one can go TU and the others be OK.

Good luck.
 

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What you have to do to fix it is start tracing back the start circuit where you didn't get voltage. When you get past a component and get voltage when you turn the key to start, that component is your problem. Be sure to use a logical approach to your troubleshooting, and rule out one thing at a time.

Could be the ignition switch. It has 4 separate switched circuits in it and one can go TU and the others be OK.

Good luck.
Thanks Klhansen - is there any particular way to test the ignition switch, specifically the circuits individually? Although extremely coincidental, I think either my ignition switch or DTRS has gone out - I recently had a no crank no start issue and pushing the shift lever all the way up to Park resolved the issue, so maybe the DTRS was on the way out when I busted the plastic starter solenoid, again this is all because I broke the plastic solenoid end on the starter motor, the motor itself was working perfectly fine but when I replaced it I ended up with this no crank no start problem...
 

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One more question in terms of the ignition switch - to confirm, you are referring to the "block" of wiring that runs from the ignition and onward to the various things those wires run to opposed to the actual ignition cylinder (for the key itself), right? The previous owner did a number on the wiring under the wheel, not sure what he was trying to do but I have a number of wires that aren't connected to anything and some that were spliced into, I don't know if this could be part of the issue...?
 

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I confirmed I don't have power leading into the starter motor on the smaller lead that's only hot when starting the motor - to check the SNS I pulled the DTRS off the side of the tranny and rotated the switch while intermittently turning the key to "start" and other than having some "clicks" which I think were probably relays I still never was able to start the motor - which makes me think it's either a fuse or relay that I missed or the ignition switch.

Does anyone have info or a tutorial on testing the ignition switch? Seems like everything I have found is about how to replace the cylinder/tumbler in the ignition but not the actual ignition switch - anyone?
 

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Thanks RT, this is exactly what I needed! I was literally just looking where I could buy the switch locally but I'll test mine before buying a new one, I'm going to check all fuses and relays one more time too just to be sure -it's just so strange that while replacing the motor I also lost the switch or whatever is killing the power source, but I did have a few no-start mornings before so maybe it is just coincidence.
 

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I am having the same symptoms. In my case it is not the ignition switch (B4 to STA shows continuity when switch in the START position). The problem is that I am not getting power to the wire that plugs into B4 -- should be a constant 12v. Anybody have an idea what should be supplying power to that wire? Fuse? Relay? Having difficulty tracing the wire through the firewall.
--JB
 

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Here's some info - you'll have to get your voltmeter out and work through each pin to see that it is acting correctly with the key in the respective positions:

View attachment 111818

View attachment 111826
RT - thanks for all the help, I tested the ignition switch and it is working properly. I used the other sheet you sent and tested the DTRS connection and didn't get any power on pins 10 or 12 but I'm not sure what that means???

Also, as I was checking fuses and relays again I noticed my fuse panel has a lot of "not used" positions with fuses in them, I pulled them out since they shouldn't be powering anything but those slots did have the metal leads that the fuses would plug into, I think this is so you could add a circuit later but I'm not sure - are the unused positions typically just the plastic "slot" without the metal contacts?

I know the everything from the plug near the passenger fender down to the starter is good, the ignition switch is good, I don't know about the DTRS, and it seems like all fuses and relays are good - just to confirm, not getting power at pins 10 and 12 on the DTRS wire harness doesn't mean the DTRS itself is bad, it confirms I have an electrical issue somewhere that's cutting off power, correct?
 

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Para_Bellum,
I found my issue and am sharing in the hopes that it'll solve yours as well.
Like you, everything from the starter relay on the fender to the starter is fine. Fuses fine. Tested my ignition switch, that tested fine in all positions. Here's what I did...

Check to see that you have 12v going to your fuse #3 (20A) in the Power Distribution Box. Set your multimeter to DCV, connect one lead to the neg terminal on the battery and probe the fuse with the other lead. Should read ~12v on both posts. If you don't show power, the problem is between the Starter Relay on the fender and the fuse -- most likely one of the fusible links. If you do have power, pull the fuse and probe the terminals that the fuse plugs into to see which one has power. The one that does not have power is the wire going to your ignition switch.

Set your multimeter to Ohms to check continuity. Test continuity between the non-powered terminal and the connector at the ignition switch (B4 in the diagram that RT sent). Mine showed an open line, no continuity.

After much blood, sweat, expletives and gnashing of teeth I traced the issue to a corroded and broken wire inside the Power Distribution Box, which coincidentally was the output wire from fuse #3. A couple of snips, strips, and a $.10 connector later to splice the wire back together and I'm back in business. Once fixed, you should show continuity all the way from the STA pin on the ignition switch to the ignition wire at the Starter Relay, and when you turn the ignition to Start you should see ~12v at the end of that same wire.

Hope this helps.
--JB
 

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Thanks JB, I'll check it out, somewhere in the process I also shorted out my new starter motor but had a lifetime warranty so I replaced it yesterday, spending some time with the family today for Independence Day so I'll try your fix hopefully tomorrow and will report back - thanks again!

Happy Independence Day!
 

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Update: Put a new starter motor in, didn't have time to test the fuses as JB suggested but did try to jump it to check everything from the "fender connection" down - motor just clicked.

When I put a wire between the ignition wire and positive battery connection to jump the starter it is now sparking at the positive battery stud, it wasn't doing that before so I'm not sure what would have changed, does this indicate a short somewhere or bad ground or could it be rooted somewhere in the fuse panel?

If I check the starter ignition wire (smaller wire, not the constant 12v wire) for continuity and confirm there isn't a break in it, what would be causing the new starter motor not to start if it has constant 12 v, 12v ignition when jumped, and a solid ground? I am wondering if by jumping the starter motor off the same battery a few times I could have drained it enough that it's too weak to jump the starter again? On top of this, when I turned the key the wait to start light flashed quickly then the battery light came on but I had no power to any electronics - does anyone have any idea what my actual problem may be or what the source is?

Thanks in advance for any suggestions, I hate chasing electrical issues and mine seem to be getting worse the deeper I look...
 

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Sparking at that stud would indicate a bad connection there. Tighten it up and try again.


Sent from my iPad using Tapatalk
 

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Thanks to both JB and RT for the help. I confirmed that the connection was just loose, so I can once again jump the starter motor and drive the truck if needed, though I'm striving to fix the starter issue before leaving the house.


JB - I ran through the procedure you suggested, when facing the dash, fuse #3 which is a 20 amp fuse DOES HAVE power on both terminals, once removed I still have 12v on the left/driver's side terminal and no power on the right/passenger side. I checked for continuity between B4 on the ignition switch and the right terminal of the fuse "plug" and had nothing, open circuit, so I'm wondering if I have the same issue you were having. Before I pull the fuse box out I'm going to do some research to make sure I don't need to disconnect anything (batteries or otherwise) to make sure I don't fry something else. If I don't find a break in that wire (which seems like I'd have to since I don't have continuity there) I may resort to spending $20 on a new DTRS just in case that's the issue and I tested it wrong before.

Can anyone send me the actual fuse diagram for a 2003 F250 with the 7.3? I pulled the official manual from Ford's website but it shows a number of fuses as "not used" INCLUDING the #3 fuse that JB/I tested (see attached photo)- so I'm not sure why but the manual doesn't match my actual fuses, I also have no fuse in the FICM spot (according to the diagram in the manual) but doesn't seem to affect anything...

One more question on the ignition wiring - I attached a photo of something (blue wire) that is spliced into A5 of the ignition switch then runs to what looks like a relay, just hanging off another wire with a zip-tie (follow the red/blue/yellow/brown wires and you'll see the black wire harness that plugs into what I think is a relay), all the other wires for this "relay" are cut or don't go to anything, it's only that blue wire -does anyone know what this is and if these other wires need to be connected? (I know this isn't affecting the starting situation because it's been like this since I bought it but it can't be right the way it is...)
 

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That last photo of yours doesn't look stock. I'm guessing someone put a remote start/alarm in at one time. That relay may be to prevent cranking if the engine is running.

Looks like you have a fun time ahead of you cleaning up.

If I can remember, I'll see if I can get you a wiring diagram tonight.
 
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