Diagnostic Aids
When attempting to diagnose an intermittent problem, use scan tester to review supplemental diagnostic information. Supplemental data (scan tester MALF HISTORY) can be used to help duplicate an intermittent problem. Using Diagnostic Service Probe (12092782) allows voltage to be read on wires without disconnecting connectors. Desired idle speed is based upon a look-up table built into PCM memory. This includes anything which requires an idle speed boost. Desired idle speed can be determined using a scan tester. Cruise cable misadjustment may cause a high idle due to throttle plates being held open. Inspect PCV valve and system. Inspect IAC valve for dragging, binding and plugged passages. Check for shorted wiring harness.