Needing help with transmission

[Dawglife]

Working on my sons 94 1500 4x4 5.7 with auto transmission. Started not wanting to shift out of first unless you let off the gas or manually shifted. He has changed the throttle position sensor, vehicle speed sensor, both shift solenoids, new fluid and filter and now it won’t shift out of first at all. No dash lights on, Speedo works . We’re not sure what to check next. Someone suggested taking the trans fuse out to see if it would start off in 3rd. We tried that and I’m pretty sure it did. He suggested the ecm is bad. Anyone had similar problems and could point us down the right path? Also, these problems literally started over night. No prior shifting problems or slipping etc. Thanks

 

[NickTransmissions]

Working on my sons 94 1500 4x4 5.7 with auto transmission. Started not wanting to shift out of first unless you let off the gas or manually shifted. He has changed the throttle position sensor, vehicle speed sensor, both shift solenoids, new fluid and filter and now it won’t shift out of first at all. No dash lights on, Speedo works . We’re not sure what to check next. Someone suggested taking the trans fuse out to see if it would start off in 3rd. We tried that and I’m pretty sure it did. He suggested the ecm is bad. Anyone had similar problems and could point us down the right path? Also, these problems literally started over night. No prior shifting problems or slipping etc. Thanks

Taking the fuse out or unplugging the case connector puts it in limp mode which is 3rd gear (sol A and B are both normally off in 3rd gear). I had a customer with a similar problem about two years ago in a 95 and his PCM turned out to be the problem.

Do you have an OBD-1 compatible bi--directional scan tool that renders live trans data?

Mechanics-wise, it could possibly be valve body but no 1-2 upshift due to a VB issue is relatively rare in these from what I've personally seen.

 

[Dawglife]

Thanks for the response. I don’t have a OBD-1 scanner. Only a OBD2. Checked local parts houses and they don’t use them either. Seems like every time he replaces a part it gets a little worse ‍‍

 

[Dawglife]

Taking the fuse out or unplugging the case connector puts it in limp mode which is 3rd gear (sol A and B are both normally off in 3rd gear). I had a customer with a similar problem about two years ago in a 95 and his PCM turned out to be the problem.

Do you have an OBD-1 compatible bi--directional scan tool that renders live trans data?

Mechanics-wise, it could possibly be valve body but no 1-2 upshift due to a VB issue is relatively rare in these from what I've personally seen.

Bought a code scanner today and it’s throwing a 81 and 82 code. Looked online and I’m seeing those codes are for the solenoids that were just replaced. Is it possible the new solenoids were bad or I’m I looking for another problem?

 

[NickTransmissions]

Bought a code scanner today and it’s throwing a 81 and 82 code. Looked online and I’m seeing those codes are for the solenoids that were just replaced. Is it possible the new solenoids were bad or I’m I looking for another problem?

Most likely another problem. Continuity-Test the solenoids via the transmission wiring harness case connector then test them directly after unplugging the harness from both shift solenoids. My suspicion is that your trans wiring harness is bad. If the harness tests good, you're looking at vehicle harness and/or pcm.

 

[Dawglife]

Most likely another problem. Continuity-Test the solenoids via the transmission wiring harness case connector then test them directly after unplugging the harness from both shift solenoids. My suspicion is that your trans wiring harness is bad. If the harness tests good, you're looking at vehicle harness and/or pcm.

New harness and solenoids installed. Still the same . Reverse takes a while to engage now. Am I headed towards pcm?

 

[NickTransmissions]

New harness and solenoids installed. Still the same . Reverse takes a while to engage now. Am I headed towards pcm?

Possibly - continue your diagnosis until you have either identified the problem or ruled out all potential electronic/electrical command and control sources, including the pcm. Delayed engagements into Reverse are usually mecanical. While you're at it, grab a transmission pressure gauge and conduct a line pressure test of the transmission. You should between 55-75 psi when in Park, Neutral, D4 and D3; 90-120 PSI in Reverse. If readings are low, continuity test the EPC. If the EPC chrcks good, your Actuator Feed Limit valve, pump and/or torque converter may be going out/excessively worn.

 

[Dawglife]

Possibly - continue your diagnosis until you have either identified the problem or ruled out all potential electronic/electrical command and control sources, including the pcm. Delayed engagements into Reverse are usually mecanical. While you're at it, grab a transmission pressure gauge and conduct a line pressure test of the transmission. You should between 55-75 psi when in Park, Neutral, D4 and D3; 90-120 PSI in Reverse. If readings are low, continuity test the EPC. If the EPC chrcks good, your Actuator Feed Limit valve, pump and/or torque converter may be going out/excessively worn.

 

[Dawglife]

By changing the harness and the solenoids should the 81 82 codes have gone away?

 

[Dawglife]

By changing the harness and the solenoids should the 81 82 codes have gone away?