todubble

I’ve been chasing this error for a few weeks. Hoping someone can repoint me in a helpful direction.

Started with only a diagnosis of limp mode and hard shifting (R and 1st).

Tried to pull codes, nothing on the scanner. Pulled ECM/PCM to find three bad caps and a fried resistor. Found a local solid state repairman to replace those (but had no means to test). After reinstall, was able to pull codes. 625, every time.

Dove into troubleshooting. Found that the E4OD solenoid pack was from a 95+ (no resistors), which I figured fried the ECM components. Replaced that with the correct part, while there tested for battery voltage at the tranny connection. After those proved to be correct, chased back pin 11 on the tranny, to pin 38 on the ECM, got 0.3 Ohms, so that wire seemed good.

Backprobed pin 38, to find 11.4 volts with key on.

Still shifts hard, still pull 625 during KOEO test.

Any ideas?

manicmechanic007

Perform the pinpoint tests for code 625
I should have them for your 1994 in a 94 PCED
I can post them later today if you need / want them

todubble

That would be great. Thank you.

manicmechanic007

Okay,
The 3 pinpoint tests have you looking into the wiring back to the processor then it sends you into testing the transmission solenoids and harness
The breakout box is needed for the 2nd test, but we used to just back probe the connectors to not have to find our one breakout box for 20 techs
I have my own now but very seldom use it
I got a feeling, when you are done with these tests you will need the service manual to do the further testing and I do not have that.
AllData does at your library though, and free in most cases to print pages



Those transmission internal harnesses get oil intrusion into the wiring. That makes the resistance in the solenoid circuits go off scale and cause big problems with the trans
It is getting harder to find new internal transmission harnesses.

todubble

Thank you.

To backprobe, I assume I leave the PCM plugged in?

For the internal wiring (tranny) where is that? When I dropped the solenoid pack it looked all contained and centralized to that unit?

manicmechanic007

The internal harness is the wiring from inside the trans to outside the trans through the big connector on the side
Yes, the processor will be plugged in
Disconnect the battery first

todubble

Ok. I bench tested the solenoid pack before I installed it, then tested voltage at the connector post install to be sure that was as appropriate.

If I’m understanding the last statement, for the tests with the PCM, disconnect the battery and backprobe per the process shown in your shared content, correct?

manicmechanic007

Right, correct
I think you might have a no answer on TC11 possibly or TC12 if you replaced that EPC solenoid already

todubble

Just to be clear, again, I tested 11 and 12 after the solenoid replacement.

KOEO - 12 had battery voltage and 11 had slightly less than that.

manicmechanic007

For pinpoint test TC 11 and TC 12 you are checking resistance on processor pins 37 and 57 back and forth to the wiring connector at the transmission and the EPC solenoid through the connector as an end result.
Then on TC12 you are checking those two wires for a short
I should have included this diagram, so you know what processor pins you are checking
You can do that either way, I usually unplug the processor when testing resistance through the wires