Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
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The most likely cause of your concern is a faulty Park Nuetral Position switch located on the side of the transmission. The older design had issue with water getting into the switch. The part number for the updated switch is 29540479. There will be a little cover supplied with the switch and it will go inbetween the new switch and the shift level at the transmission. I have replace several of these switches for this issue.
The P0700 in the engine control module is just to turn the check engine lamp on informing the technician that there are codes stroes in the Trans. Control Module (TCM).
The TCM does not have the capability to turn the check engine lamp on, so it sends the P0700 code to the Engine Control Module (ECM) and the ECM then turns on the check engine lamp. The part is approx. 250.00 dollars. This condition will set both codes.