DSR4.5 - Check Timing Using a Timing Light

- Key Off.

- Electrical loads Off (A/C, heater, etc.).

- Engine at normal operating temperature.

- Shift lever in PARK (A/T) or NEUTRAL (M/T).

- Connect timing light.

- Start engine. (Use the ignition key to start engine. do not use a remote starter.)

- Disconnect SPOUT connector.

- Check base timing. Refer to the Ignition Systems for specific instructions for checking base timing.

Base timing should be 8-12 degrees BTDC.

- Check for computed timing.

- Reconnect SPOUT connector.

Timing should change from base timing.

- Are the base timing and computed timing checks OK?

YES -- GO to Diagnostic Subroutine 5.0 DSR5 - Perform Key ON Engine Running (KOER) Self-Test

NO -- If base timing was not 8-12 degrees BTDC:
Check possible causes of incorrect base timing (damaged, loose, misaligned CKP sensor or Trigger Wheel, etc.). Base timing is not adjustable.

If base timing was OK, but timing did not change as expected: Verify results by checking computed timing while revving the engine a few times. If timing still remains at base timing, GO to Pinpoint Test Step MC1. MC1 - Check Power to PCM: VREF Circuit Voltage at TP Sensor