Chart C-5 - ESC System Pickup 3.1L: Notes

Electronic Spark Control (ESC) is accomplished using an ESC module which sends a voltage signal to 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).

1. If Code 43 is not set but knock signal is indicated while running at 1500 RPM, listen for an internal engine noise. Under a no-load condition, detonation should not exist. If a knock is indicated, an internal engine problem may exist.
2. Usually a knock signal can be generated by tapping on right exhaust manifold. This test can also be performed at idle. Test number 1) was run at 1500 RPM to determine if a constant knock signal (which would affect engine performance) was present.
3. This tests whether knock signal is due to sensor, a basic engine problem or ESC module.
4. If module ground circuit is faulty, ESC module will not function correctly. Test light should glow, indicating ground circuit is okay.
5. Contacting terminal "A" of ESC module harness using a test light to 12 volts should generate a knock signal. This will determine whether knock sensor is faulty or if ESC module cannot recognize a knock signal.