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2012 chevolet lfa 6.0 with a po641 low reference 5v. Already threw new throttle body an ecu in it already. Disconnected all the 5v reference sensors that get signal from 5v reference 1 an still low voltage. Did the wiggle test thru out the harness even exposed it in the usual place over the left engine cover. Checked the fuel level sensor harness checked harness for any rub points. Can someone tell me what I'm missing?
I would back probe the PCM at the appropriate 5v ref feed (I believe there are 2 5v ref circuits) and check for 5v. If voltage is indeed low, I would then cut that wire where it's going to be easy to fix and see if 5v is restored. If yes, then it's going to be a sensor or circuit problem. If no, then I would suspect the PCM and verify proper power and ground at the PCM before replacement.
"Ground cannot be checked with a 10mm socket"
The following user(s) said Thank You: juergen.scholl
