Diagnostic Tests: Notes

NOTE: Before performing any diagnostic test, see SELF-DIAGNOSTICS - INTRODUCTION article for diagnostic system functions and system diagnostic procedures. For component location, see appropriate illustration in THEORY & OPERATION article. To identify circuits and wire colors referenced in testing, see WIRING DIAGRAMS article. References to California emissions apply to vehicles with California emissions, which may be verified by underhood Emission Control label. Vehicles with California emissions may be available in other states.

CAUTION: If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction.

NOTE: Use illustration to identify ECM connector terminals referenced in testing. See Fig 1 or Fig 2 .

Fig 1: Identifying Engine Control Module (ECM) Harness Connector Terminals (With California Emissions)

Fig 2: Identifying Engine Control Module (ECM) Harness Connector Terminals (Without California Emissions)