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The powertrain control module controls the solenoid so I'd start by replacing pcm after verifying wiring between pcm and solenoid is good. You can get a used pcm from www.car-parts.com to save money. Let me know if you have questions, thanks.
I don't have any codes associated with replacing that. People have replaced this and ended up with the same problem
Otherwise valve body will need to be removed, dissasembled, and cleaned because this could be caused by a sticking vavle. Here is a TSB released by GM for the issue.
P0756 2-3 Shift Solenoid Valve Performance - No 2nd Or 3rd Gear - With Automatic Transmission
I had the entire transmission cleaned out looked in holes replaced solenoid twice and the harness. The fluid was always clean and no blockage
I think the guy already did alot of this stuff I know he cleaned out #29 and all that surrounded that. I do know they are known to get sticky. Is there anything else I should be looking at?
If its an electrical problem it would come up with a different code and that is not the case
I did forget this, I kind of know when it will happen cause my lights on the dash including the radio and clock with click on and off. And if the stop sign is on a uphill slope it is more prone to do it then.
How can I monitor it if it happens whenever it wants? It can go for months with no problems and then out of the blue it'll go out. Always when I have to stop in traffic.
Your going to have to connect a testlead to transmission solenoid and run it into cab then keep voltmeter on you...So when problem happens you can monitor voltage. Let me know if you have questions, thanks.
the solenoid is in the transmission
and I can drive it around like that?
Thankyou very much Dan, I will try these things out. Thanks for your time.