I need information about PCM on 2001 Grand Prix, 3.1 liter. Problem started with hard shifts with codes P0716 and P0717. Trouble shooting indicated that the Transmission input shaft speed sensor had the right resistance. The low signal wire from the transmission (C1 pin No. 62) is open, broken. There is no voltage from the PCM on ( C1 pin 63) to supply power to the sensor. The PCM has power and the engine runs. Its good that I do not have to open the transmission and I can easily repair the broken wire, but I do not know how the sensor works or the power required. Is the PCM broken? I would appreciate some input from someone with experience with this.

JAS
2001 Grand Prix SE 3.1

Looks like you have done most of the work, and are on the right track.......

You tool a resistance reading at pins V and *, at the connector on the tranny, and it was ok?

You then took a resistance reading at pins 62 and 63 of C1, and got infinite resistance, meaning an open circuit? Then you narrowed it down to circuit #1231, being open.....

So yes, I would repair the line.......usually those lines will break near the transmission connector rather than the PCM connector....sometimes the harness flexes too much, or it rubs against something causing a break, like one of those studs coming out of the transmission......What you can do is attach your ohm meter to pin 62 at the PCM connector......then using a wire piercing connector take a reading away from the end of the transmission harness, say 1-2 feet away......if you now get zero for a reading, you know the break is between where you pierced the wire and the end of the transmission connector.......now work your way back to the transmission connector until you get an OL reading, and you will have found your break......

As for your voltage question, there is no voltage supplied by the PCM on either circuit 1231 or 1230....the input speed sensor generates it'* own voltage .....it'* A/C voltage....with very low voltage at low rpms, to very high voltage at high rpm'*......so if you were measuring with a meter on DC you would get nothing, because there is none.....and you would get nothing on A/C voltage, because you have an open circuit......once you repair the line, then the PCM will receive an A/C voltage from the sensor....

Thank you so much. This clears up the mystery.

JAS