Chart C-5, Electronic Spark Control System Check: Notes

Internal sensor circuitry causes the 5-volt reference signal from the ECM to be pulled down to about 2.5 volts DC under no-knock conditions. The knock sensor produces an AC signal which rides on the DC signal when detonation occurs. The intensity of this signal depends upon knock frequency. The MEM-CAL takes the place of the ESC controller on this vehicle.

1. With the engine idling, there should be no knock signal present.
2. Tapping the lift hook bracket should simulate a knock signal to determine if the sensor is capable of detecting detonation. If no knock is detected, try tapping on the engine block closer to the sensor before replacing sensor.
3. If the engine has internal problems which are creating the knock, sensor may be responding to internal mechanical failure.
4. This test determines if the knock sensor is faulty or if the ESC portion of MEM-CAL is faulty. If the MEM-CAL is suspected, be sure that it is properly installed and latched in place.