i have all the wiring diagrams i need, thanks though, and iv checked the wires and they are good. i have cleared all fault codes before test driving it each time. what vacumm line are you talking about?

 

On my 93, the fuel pressure regulator is on the rear of the fuel rail on the drivers side rear of engine. Going into the FPR is a small, rubber (not one of those small hard plactic vacuum lines) vacuum line. I am running with it disconnected and plugged now.

My 93 would, at certain times (not every time but frequently), not even crank without going through the key on, key off several times for the recharge of the rail/injectors. Then it would crank, but run very rough, turn on the check engine light and the tranny would almost not work (limp home). Since I removed the vacuum line, it has not done that--even once.

It tells me its something at the FPR. If it were the pump, I wouldnt expect it to work at road speed---even hard kickdowns. With the line connected, it is supposed to cut back the pressure in the rails at high vacuum for lower fuel demands at idle/low speeds.

Sounds like you have a good handle on the wiring thing, so LOL

 

Yea iv been on this project for a while now and its been a bum, so i started this forum to get more ideas. Ill take a look at that vacumm line. Will that get me worse gas mileage if i went that route? Thanks.

 

I hope I voiced my concern about the internal electronics properly. If I read the posts correctly, the melted EXTERNAL wiring situation was not detected until AFTER the rebuilt tranny was installed. Melted, damaged wiring on the OUTSIDE has the potential to short out the INTERNAL components as well. And its not like fixing the external wiring is going to miraculously fix any internal problems that may have been caused by the original damaged external wiring issues.

 

There are some tests with a multimeter (ohms) that can be done to check the internal condition of the tranny. It might be a bit of a PIA to get good readings from the connectors to the tranny. 2 of the wires are the 12v feeds to power all the relays. 1 of those wires (R) on term 1 of the tranny connector feeds 4 solenoids, Coast clutch, #2 shift, TQ Conv Clutch, and #1 shift and is a common feed internal to the solenoid pack. The grd/rtn feeds are separate for each on term 5(BR/O)--CC, term 2(P/O)--#2 ,term 4(P/Y)--TCC, term 3(O/Y)--#1. The 2nd 12v feed is on term 12 (W/R) and feeds the Electronic Pressure Control Solenoid. The Grd/Rtn feed is on term 11 (W/Y)--EPC. For the 93 yr, those pins are in the 1048 connector at the tranny.

Getting a probe to that connector and making a good enough contact to measure resistance of each solenoid winding may be a real birtch. Another option is to go to connectors 110 and 103, which appear up on the drivers wheel splash shield, just about under the front of the Master cyl and try to measure from there. For all this, you really need a wiring diagram to stare at.

The ATSG E4OD Techtran Manual shows a "pigtail" harness to test all the solenoid windings for resistance. All the solenoids should have 20-30 ohms resistance, measured from pin 1 to each of the pins for each solenoid. A little complicated sounding if you dont have some troubleshooting experience and working with a multimeter.

I agree with greystreak, if the wires burned after hooking up the new tranny, just fixing the wires may not fix the problem. Depending upon what wires melted, you could have a short that goes directly to the PCM and may have burned pins on it. I dont know exactly what would happen if 12VDC (directly from a fuse position) is applied directly to a PCM pin that has a GRD/RTN output. If there is not enough internal resistance in the PCM to shunt the 12V, you may well have messed up the PCM and will mess up any replacement PCM until you correct the wiring problem. I really dont know what to suggest at this point, except to verify all the wiring. Maybe someone else can do better. Alias--the plot thickens!! Sorry for the long post, hope it helps---some at least

 

The wires going to the tranny were striped back about 1cm. Looked like someone did that to test the wires and never covered them back up, so they ended up meltin and crossin to each other. I highly doubt this happened after the rebuilt tranny was installed. Looked as if it had been done a while back. I am leaning more towards the PCM due to what you said, if something was shorted out by wires melting and crossing to each other it very well could of shorted out the PCM.

 

One more thing that has caused me a problem on a connection---you may already know about it--. The pins, both on the male and female side of the connectors are held in place by small "reverse" tangs that keep them from backing out. I have had a few that those tangs bend a little and all the pins to look good when disconnected, but will "push back" into the connector and cause a bad connection. I usually take a piece of old wooden toothpick press on each pin in the connectors, while disconnected (of course ) to make sure they are locked in.

Hopefully your problem is in a connection/input to the PCM and not a bad PCM. If you have been looking at wiring a lot on this thing, good chance thats possible. I guess you have the pin-outs for the PCM and connectors in that path? LOL

 

ok ill check that out...thanks.

 

My concern is not WHEN the wires melted and shorted but the possibility that the crossed (shorted) wires were still in that condition AFTER the rebuilt tranny was installed. Thus leaving the shorted wires to do damage to the transmission internals once things were reconnected and power applied. If that is not the case then there would be no worry that the internal electronics have been subject to this kind of damage.

 

I am having the same kind of problem with mine. I don't have the wiring problem, but it is doing the same thing. It will take off a lot better while in
4x4 low, but if its in 2 wheel in drive it seems like it is trying to take off in high gear and it will not shift. After the the New Year I am going to try and find a used ECM & try that. Because I would like to trade it for a 75 or older
F-150 or something.

Bill

 

That sure sounds like something set a hard code in the PCM and is causing the tranny to quit functioning AKA limp home. I guess you have pretty well checked all the other stuff and pulled the codes. Maybe I can look at my ATSG manual and see what codes will cause that problem.

I have a problem with used electronics, but if you can get a used one to test before you buy, maybe it will help.

 

pull codes and report what the codes are. so far we havent seen a code that you keep clearing from the ecu. the ecu is giving codes then its not the problem like greystreak has stated.

 

i put a brand new ECM in it and it did not help anything...im gunna look more in depth to see if i have damaged anything internal in the tranny.

 

just got back to the forum deal. i fixed the problem a while back. the electronic valve body in the rebuilt tranny i bought was shorted out and coused the wires to be damaged. i replaced the valve body and everything works great now after that and fixing the wiring.