This is where I’m at with this 2000 2500 v8 truck. Been dealing with this for a year now. Long story long. Truck sat 11 years for bad trans. Fixed it up and drove it and it was shifting like **** and had no first gear. Changed solenoid and it was fixed for about 2 months. Going down the highway and when I got off light came on and thing would barely get moving . Limp mode lol. Changed solenoid again and it was fixed for another month . Drove down highway and when I got off and drove around for a bit same codes came back. Changed solenoid again with oem one and same code , never could clear it. Changed connector in harness since it seemed loose and still same code. Went through about 5 computers , all junk computers truck wouldn’t get code with computers but will still sometimes start with second gear or third and erratic shifting. Got trans rebuilt since I drove it with limp mode and destroyed the converter. It was all I had as a vehicle. **** only has 100k miles or so. Where should I check wiring wise ?? Any checklist to go through and obvious things? Grounds ?? Checked pins in fuse box and ground for solenoid is weak but if ya mess with pin a bit it gets a stronger signal . Truck just goes right in limp mode when starting up even after disconnecting battery for weeks on end. Don’t think it’s the harness in trans as it has been checked or connector it’s something above that . Just don’t really know what to check. All sensors have good volts that don’t fluctuate. But solenoid will sometimes not read pressure when in drive and it will do that 2nd or 3rd start, then randomly start reading after going a couple mphs. Just looking for people that had same issue, don’t think it’s the computer anymore if it does it with other computers just doesn’t trip a code. I heard people will get that code if maf sensor shorts or 02 sensor , truck does have a low idle and starts sucking mad air and seems to run odd at low idle. Does have a very mild cam though and ram air intake. Truly need help. Wiring checks out but the computer must sense something and it’s right I believe. Have yet to change relay and if it’s the relay I’m burning it to the ground 🙃 The fuse for trans circuit has blown once when testing relay. Things honestly a mystery and just a lemon. Low miles = more issues.

 

Have you changed the pressure sensor?

 

Yes , have changed them 3 times. Have yet to change the 3-4 gear solenoid and tcc.

 

If you aren't getting codes for those solenoids, just leave 'em. If it ain't broke, don't fix it.

Will your scanner read live data?? Do you have a service manual for your truck? (if you don't, get one here.)

 

Yes I have a scanner that reads live data, the thing is the code trips a limp mode, starts in 3rd and then only has 3rd and 4th gear. I have a video of it driving with the scanner with an old solenoid that was bad before I replaced it, after replacing it the pressure was fixed but just watch the volts and duty cycles. Ok video won’t work but here’s a picture. Only thing that seems off it’s the volts, they would go up with acceleration. But this was a year ago, before I changed the solenoids. The new one reads fine but doesn’t start reading until after a couple mph in first or second gear, doesn’t get power in drive doesn’t read nothing in drive. Odd . Definitely a power issue or ground issue I just need help on what to check first before putting a **** ton more money into it. Don’t want to take it to dealership and get charged crazy either.

 

Wow, pressure is WAY below what the PCM wants...... an internal leak somewhere??

 

yeah that’s the weird thing, see how the volts are low? Give it more gas and it reads higher . Let off gas and pressure just drops. The more volts , the higher the solenoid reads, it’s not getting enough volts to read its desired pressure, even at idle sitting still. This was happening way before I got the trans rebuilt. Trans has been rebuilt and still same issue. Should I try changing the idle air and throttle position sensor again ?

 

That won't matter....

Bad connection somewhere???

 

exactly my man thank you. I need to know other than the manual where to check connections other than the plug at the trans and connections in the trans. I have ordered a new pigtail and connector for trans and gonna redo that to see if it changes anything even though testing the wiring it checks out. But yeah I know people have delt with this before and it’s usually something stupid lol

 

Also check the connectors up at the PCM. I don't think there are any other splices/connections between them.

The connectors are notorious for wires pulling out, and shorting, and the connectors inside expanding, and not making a good connection. Your meter will tell you everything is fine, but, in reality, it ain't. Check/clean the connectors at the PCM, replace the pigtail, see what happens.