Chart C5 - Electronic Spark Control (ESC) System Check
Electronic spark control is accomplished with a module that sends a voltage signal to ECM. As the knock sensor detects engine knock, voltage from ESC module to ECM is shut off and this signals ECM to retard timing.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- Tests ESC to see if it can detect a knock and can retard spark timing.
- By disconnecting ESC module, ECM sees low voltage at terminal B7 and should retard timing. After approximately 4 seconds, "SERVICE ENGINE SOON" light will come on and Code 43 will be stored.
- Checks for proper voltage output (measured on AC scale) of knock sensor. Low or no voltage would indicate an open circuit to terminal E or faulty sensor.
- Checks to see if constant retard is due to a faulty knock sensor or module, or if a false voltage signal is being transmitted on wire from knock sensor by induction from an adjacent wire, such as a spark plug wire, ignition wire, etc. Re-route wires as necessary.