Credit: Travis Barker

Issue:

• Got a few codes the other day that put the car into limp mode P0643 P2122 P2138. Thought the issue was the Pedal position Sensor until I replaced it and cleared the codes so I could start the relearn process, but the p0643 code didn’t go away. I Tested the Sensor Power supply but the voltage was about 3.88V from both the pedal position sensor end of the harness and the terminal circled in the photo coming straight out of the ECM I tested the other pedal position sensor power supply and it was showing 5.02V.

Diagnostics:

• Update had my ECM sent out to be tested and repaired, was told they weren’t able to find any issues with the output voltage but there was something inside which was “unrepairable” that didn’t look right so they asked if I wanted to buy a new pre programed ECM and of course I said yea sure, about 2 weeks later the ECM came put it in still had the P0643.
• Checked all my grounds and noticed one was loose but the head of the screw thats holding it is facing the other way inside of the dashboard, so the only way to adjust it is to remove the dashboard and tighten it. So I took apart the dash and moved it slightly enough to just reach and tighten the ground screw, turned the car on boom p0643 still there.
• Went back into the FSM and started to wonder about the 2 sensors I didn’t check the voltage on which was the power steering pressure sensor and the EVAP pressure sensor. Jacked up the rear and checked the EVAP pressure sensor for water in the connector and the power supply voltage, it was about 2.88 volts.
• Then decided to check the power steering pressure switch, The connector looked fine but the tubing around the harness felt hard like heat got real close to it. I put my hand up farther to feel the rest of the harness and found the issue, the harness for the power steering sensor melted and joined together.

Solution:

• Once I cut off the burnt end on power steering switch, separated the wires and cleared the code everything works as it should! So for anyone with the p0643 issue be sure to check all the sensors and the harness showed in the FSM!

Photo of Power Steering Switch Plug: