1999 Chevy Silverado 1500 5.7l
P01 Computer
Trans has 3400 stall, sonnax valve body parts kit, sonnax forward, 1-2, and 3-4 accumulator, super hold servo, backing plates, and im sure i am missing some.
My issue is P0748 "electrical pressure control solenoid A" i can clear code and everytime the truck gets over 2500 rpm it comes back. It doesnt matter if it is idling, driving, cruising whatever the code comes as soon as it gets over 2500 rpms.
i have replaced all the solenoids, the trans harness, and checked the ohms of the solenoid by itself, the ohms at the red pcm connecter between #5 and #8 and it all checks good. i am not getting any continuity from either wire between any other wire or ground. i have read forum after forum and nobody has seemed to solve this issue. I have some datalogs from driving while it does it if those would be helpful but it doesnt really show anything except for the fact that once i get over 2500 rpms the PCS line pressure goes to 90, the PCS desired and actual current both go to 0.
Here is log and tune, tune has not been messed with since i bored it out and did prc heads. trying to get all the issues worked out before i worry about tuning. also in the log everytime the desired and actual pcs voltage comes back means i cleared the code and it started working again.
Try changing the Error Mode to no error reported. Also, put a gage on the trans so you can see the real pressures. You do know that if the command goes to zero the pressure goes to max?
yes, that seems to be what i cant figure out it shouldnt be going to commanded 0 and the line pressure shouldnt max out unless closer to WOT but its doing it even if im in park and just rev it up. not really loooking forward to pulling the transmssion out to rebuild because my line pressure burned it up and i didnt even get to drive it hardly.
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