jmuck

Alright guys. So I tossed in a aluminum 5.7 to get me by until I get the real engine done. After a few new TPS sensors, entirely new throttle body and checking all of the wiring and grounds I have a P1515 HC fault. Soon as I turn the key on it throws P1220, 1221, and 1516. Car will start and idle and I can clear the 1220 and 1221, but the 1515 stays. Throttle will will let me idle up to 2,300 but no higher.

Any ideas? I’m almost leaning towards tuning as the tune is from my PRC 237 headed 370 and it’s tweaked just enough to get this set up to start and idle. Any help is greatly appreciated.

jmuck

With key on engine off and codes cleared, I can depress the the throttle and the 1515 doesn’t come on until I let off the throttle.

Kmoney98

Did you ever get this figured out? I have the same issue but I can get my codes to clear once the car is warmed up and it will drive fine then they cam back the next day once its sat overnight.

C5 Diag

You are throwing that P1515 because the PCM sees that the commanded (desired)and actual (indicated) throttle positions aren't correct. If you have a scan tool it's easy to troubleshoot....if you just have a multimeter you can do the same checks. I've enclosed 2 pics of what my TPS 1 and 2 voltages look like at idle and at WOT...key on engine off....after you obtain these voltages (idle and WOT) back probing the 2 signal wires at the TPS Sensor now disconnect the TAC motor harness on the left hand side of the throttle body....check both voltages at idle and when you open the throttle blade by hand to WOT...the voltages should be the same or VERY close !!...you may have some wiring issues between the TAC motor and the TAC Module...open, short to power, or a short to ground !!