Diagnostic Aids

At normal operating temperature, idle must be within 100 RPM of desired RPM or DTC P0506 or P0507 will set. The malfunction history will store the desired RPM as well as the actual RPM at the time DTC is set.

If either DTC P0506 or P0507 becomes active during a drive cycle, PCM will run an intrusive test if vehicle is at steady throttle cruise of 20-40 MPH with airflow between 4-10 gm/sec. When these conditions are met, PCM will issue a motor move command while monitoring MAP sensor value.

If no MAP sensor change is detected during the intrusive test, the high and low idle conditions detected is probably due to an IAC valve circuit problem. The scan tool's idle control table will indicate if an intrusive test has ever been performed since the codes were cleared. If an idle problem is detected and PCM never ran an intrusive test, the IAC circuit must be checked for proper operation.

IAC terminal resistance between terminals "A" to "B" and "C" to "D" should be 40-80 ohms. Terminals "A" to "C", "A" to "D", "B" to "C" and "B" to "D" should be infinite (open).