Chart C5 - ESC System Check
Electronic spark control is accomplished using an ESC control module that sends a voltage signal to the ECM. As knock sensor detects engine knock, voltage from ESC module to ECM is shut off, signaling ECM to retard timing (if engine speed is greater than 900 RPM).
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- If a Code 43 is not set, but a knock signal is indicated while running at 1500 RPM, listen for an internal engine noise. Under a no load condition, there should not be any detonation. If knock is indicated, an internal engine problem may exist.
- Usually a knock signal can be generated by tapping on the right exhaust manifold. This test can also be performed at idle. Test No. 1 was run at 1500 RPM to determine if a constant knock signal was present, which would affect engine performance.
- This will test whether the knock signal is caused by the sensor, a basic engine problem, or the ESC module.
- If the module ground circuit is faulty, the ESC module will not function correctly. The test light should light, indicating the ground circuit is okay.
- Using a test light from 12 volts at circuit No. 496 should generate a knock signal to determine whether the knock sensor is at fault, or the ESC module can't recognize a knock signal.