Detonation Problems

1. With engine running at fast idle speed and transmission in Neutral or Park, tap exhaust manifold lightly and repeatedly. Check for spark timing retard with a timing light. If retard is noted, check other engine detonation causes.
2. If no retard occurs, disconnect 10-pin connector from ESC controller in passenger compartment. Connect voltmeter leads between pins "B" and "K" of connector. Voltage should read 80 millivolts (.08 volts). If so, proceed to step 4).
3. If voltage reading was lower than 80 millivolts, disconnect detonation sensor wire. Measure voltage from sensor wire to ground. Reading should be more than 80 millivolts.
4. If low, replace sensor. If OK, check wires from pins "A", "B", and "K" of 10-pin connector for opens or shorts. If OK, repair sensor connector. If not OK, replace or repair wiring harness.
5. If resistance reading in step 2) was OK, try to start engine with 10-pin connector disconnected. If it starts, replace distributor's HEI module.
6. If engine will not start, reconnect 10-pin connector to controller. Disconnect sensor wire from sensor, and insert a jumper wire into sensor wire connector. With engine running at fast idle speed, lay wire on top of distributor over ignition coil. If spark timing retard occurs, replace sensor.
7. If no spark retard occurs, connect voltmeter positive lead to pin "H" of 10-pin connector and negative lead to pin "K". With ignition switch "ON", voltage should read more than 0.2 volt. If voltage is more than 0.2 volt, replace ESC controller. If less than

0.2 volt, repair open wire from pin "H" in ESC harness.