DSR4 - Verify PCM Control of Timing

- Scan Tool connected.

- Start engine.

- Engine at normal operating temperature.

- Access "IAC" PID on Scan Tool.

- While monitoring IAC duty cycle (%), disconnect the in-line SPOUT connector. Allow IAC duty cycle to stabilize then reconnect SPOUT connector.

- Does the IAC duty cycle change at least 2% when the SPOUT connector is disconnected and connected?

YES -- The PCM is controlling timing. GO to Diagnostic Subroutine 5.0. DSR5 - Perform Key ON Engine Running (KOER) Self-Test

NO -- GO to Diagnostic Subroutine 4.5. DSR4.5 - Check Timing Using a Timing Light