Code 43 - ESC Error (Without ESC Module): Notes

NOTE: Test numbers refer to numbers on diagnostic chart. If an audible knock is heard from engine at idle, repair internal engine problems before proceeding.

If tapping on engine does not produce a knock signal on scan tester, try tapping engine closer to sensor before proceeding.
ECM supplies a 5-volt reference signal on knock sensor line. With knock sensor connected, this signal is pulled low to about 2.5 volts. Knock signal, which is an AC signal, rides on this 2.5-volt DC signal.
This test determines if knock sensor is faulty or if ESC portion of MEM-CAL is faulty.