Hello Ford community. I have a dilemma. After a transmission rebuild I had a failure of the transmission range sensor (TRS). The transmission would shift hard into each gear. After researching I climbed under the truck to find the wiring harness plug to be very deteriorated with exposed wiring causing shorts. Contributing to the condition was a piece of electrical tape pinched between the fluid pan and transmission which acted as a wick drawing fluid directly to the connector on the TRS. I took the truck back to the transmission shop where they did a half *** job of insulating the wires. Three trips to the shop later I still have TRS problems. This is confirmed by auto zone and O'Reilly's hand held diagnostics. I finally decided to tackle the problem on my own. I bought the harness and new TRS. I cut each of the 11 wires 1 by 1 and butt connected being extra careful not to mismatch. I'm convinced that I did this correctly. When finished all was good, engine light off. This lasted 15 minutes of driving and problem returned. Been scratching my head for days and very frustrated. Looking at the old plug that I removed I noticed heat shrink on each of the wires. This was from the efforts of the transmission mechanic. There were no cuts in the original wiring so I can only assume the mechanic pushed the pins out of the plug to get the heat shrink on the individual wires. It may be, though I can't be sure, that a wire may have been mismatched to the plug. I can see colors on the existing (original) wires, on the truck and old plug connector, but if the wires were mismatched this means nothing. My questions are, does anybody know where to find out what color wire goes to which pin location on the plug? And/or does anybody have any ideas or suggestions? Thank you.

 

Pin out attached.

What is the "problem" that returned? hard shifting? That usually isn't a DTR issue unless the PCM is getting illogical information in which case it can drop into it's failsafe mode which sharply increase EPC pressure.

 

Thanks for the reply. Yes, hard shifting is the sympyom/problem. Code P0705 TRS malfunction according to two diagnostic sources. I am very greatful for your time and the diagram you posted. This may be all I need to ensure the proper connections provided the colors match up. I am interested in the rest of your thread where you posted the following:

"That usually isn't a DTR issue unless the PCM is getting illogical information in which case it can drop into it's failsafe mode which sharply increase EPC pressure."

Can you dumb it down a notch. Given the information I've provided above, codes and whatnot, the business with the PCM logic and failsafe mode is foreign to me. What is your suggestion/advice exactly? Thanks again.

david

 

The additional information you provided with the DTC (should have been included initially) does indicate that the PCM is confused about what the DTR switches are telling it.

If you have a scan tool that can read the PID for the DTR switch, you can run the shifter through the gear positions and see if you've got one or more of the bits stuck either high or low and that will tell you which signal line(s) need focused attention.

The schematic for the DTR switch/PCM connections is attached. Perform continuity checks for each of the 4 logical signal lines and the single power source line between the switch and the PCM. If those all pass, perform a short check for each of those lines to each other, including the power source line.

Post any relevant data that might need explanation and I'll see what can be done.

 

Thanks again for the info. Going forward I'll be more thorough providing relevant information. I'll run the checks you've described and let you know the results.

 

You do need to confirm you have a E4OD and not a 4R70W. TRANS code on the door jamb sticker - "E" is E4OD, "U" is 4R70W.

 

Good point.

I assumed an E4OD due to the 5.4L which is what my old truck had. I have no idea if the 4R70W was ever mated to the 5.4L in that year.

 

In 97 and 98, they came both ways. In 99, the E4OD was renamed 4R100 and was quite rare in the F150 - almost all were in the 7700 package and Lightning. The later years 7700's even had the 4R70W.

 

E4OD is the transmission type.

 

After examination of the old connector it appears that the wires and pins are matched correctly. I will perform a visual of the connections I made to make sure they're spliced correctly and post my findings when I return easter weekend. Thanks again for all the help.