Customer Concern: The check engine light is on with an ignition failure sensor code of P0320 and the tachometer is not working.
Tests: 1. With the engine running, check for battery voltage to the ignition failure sensor on the Pink wire, less than 0.05 volts on the Black wire, and battery voltage from the ignition failure sensor on the Black/White wire.
2. With the engine running, scope the signal on the Yellow/Red wire from the ignition failure sensor. The signal will increase in frequency as the engine RPM is increased.
3. Verify that the connection at the ignition failure sensor is clean and tight.
Potential Causes: Ignition Failure Sensor
Ignition Failure Sensor Wiring
Confirmed Fix: Replaced Ignition Failure Sensor