Typical E40D trans slips in and out of overdrive - Diesel Forum

rotaryboots · 09-11-2008, 07:13 PM

The truck is a 1990 F250 7.3 idi with 150K on the odometer. The engine runs perfect and the only problem with it is it will slip in and out of overdrive everyonce and a while. getting it to go back in is either turning the OD switch on and off again or slowing down and then driving normal again.

Since I fix engines and not trans's I could use some ideas and general locations of where a faulty component might be. If i know what and where to look for something I can diagnos it and fix it. I just don't know what I'm looking for to fix this problem. And yeah I did some searching and found one or two posts that had some solutions but the poster didn't confirm if what he tried fixed it or not.

Any help is appreciated

Snotzalot · 09-11-2008, 07:23 PM

Typical symptoms that you have indicate a bad TPS. (Throttle Position Switch), or a dirty plug connection of the wiring harness that plugs into the pass side of the trans. Usually just R&R of the plug will clean the connection enough to eliminate the OD problem. Search the forum for FIPL or TPS to see how to test. What color is your TPS?

rotaryboots · 09-11-2008, 07:26 PM

cool. I'll clean up the passenger side harness and all its connections, then test the TPS on it. Any suggestions on testing the switch?

Snotzalot · 09-11-2008, 09:18 PM

Do a search in this forum using the keyword FIPL or TPS. Lot's of info.

Usually just R&R he plug is all you need. Blow out the socket to check for water.

rotaryboots · 09-27-2008, 08:03 PM

Well I have a new problem on it. Since I bought the truck I have had to put it in 1 first and then into D once its in gear. Above that there is the OD slip too.

Do you guys think the cleaning the plug and checking the FIPL will fix that too or is the 1 to D a different problem.

I'm gunna hook it up to the Snapon Modis pretty soon here and check the codes but right now the OD light doesn't come on to indicate a code but maybe it does and I just don't see it coming on i dunno

icanfixall · 09-27-2008, 09:59 PM

Change the tps switch. They are supposed to be replaced around 50,000 miles. When the short out and get flat spots along the range it makes the cpu go into limp home mode. May be your problem....

M.L.S.C. · 09-27-2008, 11:42 PM

Rotaryboots, just a heads-up on the harness plug cleaning - the darn thing has two clips that hold it to the socket in the trans case, one clip is right towards the exhaust pipe and you can get it very easy, however the other is on the back side of the plug between it and the trans case - my outboard clip was busted and I ended up killing the inboard one as well while trying to pull the plug out, so I had to fab up a small bracket attaches to one of the heat shield bolts and then goes up near the plug so I could zip-tie the harness to it so plug don't come off while I drive on those lovely awesome-smooth roads we got here. So yeah, watch out for them clips, can ruin your day in a matter of minutes.

rotaryboots · 09-27-2008, 11:55 PM

Got it, I'll be watching out for the clips and make sure I take my time to get them disconnected correctly. A new FIPL sensor is on the list of parts to buy for it too. As of right now I'm gunna double check it to make sure its got the right voltage at idle and WOT and if I can't get it to set right I'm making the call to get ahold of a new one stat

Mark Kovalsky · 09-28-2008, 09:25 AM

Quote:

Originally Posted by rotaryboots

As of right now I'm gunna double check it to make sure its got the right voltage at idle and WOT and if I can't get it to set right I'm making the call to get ahold of a new one stat

You're wasting your time with the old sensor, and probably wasting your trans, too. Even if it sets just fine at idle and WOT it's probably worn out in the middle. Either replace it now or replace it after it trashes your trans.

Mr_Roboto · 09-28-2008, 09:53 AM

The Modis isn't going to tell you much. You are dealing with an EEC system and the self diagnostics are pretty limited.

The Tach Sensor and TPS (what Ford calls an FIPL sensor) are the big failure items. Failure of either one will cause improper shifting.

rotaryboots · 09-28-2008, 02:51 PM

Alright guys I'll buy a new FIPL for it. Only reason I haven't bought one yet is because I don't wanna spend money buying a part that doesn't need replaceing. This truck was well maintained before I bought it so I don't doubt that the sensor has been replaced once already.

the tach works like it should so I don't think the tach sensor is bad.

The modis will won't self diagnose like OBD will but it will give me codes and I can make it test any sensor on the truck and it will give me a pass or fail report on the sonsor tested. Further more it has a troubleshooting guide built in it to lead me to the problematic sensor. BUT I don't have it on hand right now so this is why I'm asking your advice.
Thanks

rotaryboots · 10-01-2008, 06:17 AM

I found what could be a big problem. My speedo hasn't worked since I bought this truck a few weeks ago and the trans problem came with the truck. I figured the speedo not working is just a broken cable as usual.

Well I'm searching, reading, and finding out that the VSS controls the speedo and trans so I went investigating the VSS and guess what I found. I found the VSS on the diff but what I didn't find was wires going to it. Shortly there after I traced the wire loom and found the two wires that I believe to go to it. They are a green with black stripe and a red with what appears to be a lighter colored stripe. Problem with those are they got cut right in the middle and all I have is two wires with no VSS connector. Getting the right spades for the VSS is no problem or getting another VSS but is there a certain order the wires go on the VSS like:
Left VSS connector= green w/ black
Right VSS connector= Red w/ light color?

or is it visa versa?

Such a simple fix but I'm affraid hooking it up backwards will hurt something even more so I'm making sure I hook them back up correctly... Who knows maybe this is the problem all along

M.L.S.C. · 10-01-2008, 04:33 PM

Rotaryboots, I got a '90 truck as well, give me a few hours till I get done with work and classes and I'm gonna crawl under my truck and see which wire goes where. However what I'd recommend you do, is instead of attaching whatever-fits spade connectors, to go to a junkyard and pull the actual connector plug with some of the wiring, then splice the old wiring that's cut to the "new" pigtail, this way the plug will stay where it belongs even when you drive down bouncy dirt roads and such.

rotaryboots · 10-02-2008, 12:56 AM

Yup I'm gunna go to the yard and get one tomorrow. Until then I got two stud style connectors and connected the two wires back up and found that one way I hooked it up the ABS light still stayed on, I then reversed the wires and then the light went out so I assume thats correct.

But, the speedo still doesn't even budge. I guessing the speedo cable is broken so I'm gunna find out a way to check the cable, unless, you guys have an easy way to say if it works and is not broken...

I found some service records and found that the FIPL was replace the beginning of the year and I also found reciept or paper that says something about the FIP and I looked on the side of it and it says "remanufactured" and 2007. SO, thats good news. I tested the FIPL and its at .96 at idle and about 4 at WOT and I used an old meter and there were no dead spots in its range. I'm ruling the FIPL out of the equation so far.

Next thing I'm gunna look at is the main trans connector again. I looked at it yesterday night really quick and found that I could easily unplug it and there were no clips holding it down. When turned the key to ON and wiggled the connector I could hear a solinoid or two clicking so I'm pretty sure I've got a bad connector and its slipping might be caused from vibration and it intermitantly cuts out power to a solinoid heance causing a slip and all its problems.

I should probably mention that it will hold no matter what in 1 or 2 but the problems are all in D...

Well whats your thoughts on this guys?

M.L.S.C. · 10-02-2008, 01:47 AM

Quote:

Originally Posted by rotaryboots

Yup I'm gunna go to the yard and get one tomorrow. Until then I got two stud style connectors and connected the two wires back up and found that one way I hooked it up the ABS light still stayed on, I then reversed the wires and then the light went out so I assume thats correct.

Good, saves me crawling under truck and fighting dirty harnesses, tis *****in cold here now, man I hate what's coming our way in a month or so.

Quote:

But, the speedo still doesn't even budge. I guessing the speedo cable is broken so I'm gunna find out a way to check the cable, unless, you guys have an easy way to say if it works and is not broken...

Pull it off the trans, see if you can spin it with a cordless drill.

Quote:

I found some service records and found that the FIPL was replace the beginning of the year and I also found reciept or paper that says something about the FIP and I looked on the side of it and it says "remanufactured" and 2007. SO, thats good news. I tested the FIPL and its at .96 at idle and about 4 at WOT and I used an old meter and there were no dead spots in its range. I'm ruling the FIPL out of the equation so far.

A remanufactured FIPL seems a bit weird, wouldn't think anyone considers a TPS worthy of a rebuild, besides how the heck did they rebuild the thing anyways seeing how tis all closed and sealed?

Quote:

Next thing I'm gunna look at is the main trans connector again. I looked at it yesterday night really quick and found that I could easily unplug it and there were no clips holding it down. When turned the key to ON and wiggled the connector I could hear a solinoid or two clicking so I'm pretty sure I've got a bad connector and its slipping might be caused from vibration and it intermitantly cuts out power to a solinoid heance causing a slip and all its problems.

Yeah, your clips are broken, that's why tis so easy to unplug. Also, there should be a rubber o-ring on the connector, it seals against water and other intrusions, make sure you got that one either on the harnessplug or in the one in the trans, as without that o-ring and without the retaining clips the plug will vibrate and possibly damage itself.

Quote:

I should probably mention that it will hold no matter what in 1 or 2 but the problems are all in D...

See, that I don't know about, maybe tis the OD band engagemen solenoid that gets the crappy signal from the harness?