Diagnostic Aids
Engine should be idling while monitoring QDM status. Using scan tester, monitor QDM status while moving related harness connectors, including ECM harness. If the failure is induced, a fault will status while moving related harness connectors, including ECM harness. If the failure is induced, a fault will appear on scan tester. This can help to isolate intermittent problems. If code persists with no apparent problems, replace ECM.