Self-Diagnostic System Check
The self-diagnostic system check is an organized approach for identifying a problem caused by on-car computer controlled electronics. Understanding this chart and using it correctly will reduce diagnosis time, prevent unnecessary replacement of parts, and reduce comebacks.
Test Number 1) Service Engine Soon telltale light at key ON confirms battery, ignition, and ground integrity to ECM and also verifies Ignition 1 power feed to IPC.
Test Number 2) IPC odometer is primary display device for diagnostics and must be functional in order to use self-diagnostics system.
Test Number 3) ECCP serves as access for onboard diagnosis and must be functional in order to use self-diagnostic system. A display other than standard temperature indicates fault that must be corrected before diagnostics can be entered.
Test Number 4) After entering diagnostics, record all displayed trouble codes and note those that display CURRENT and HISTORY code. Codes displayed can be diagnosed using the procedures outlined in referenced articles, but those codes displayed as HISTORY are not presently failing and may require visual inspection of circuitry to isolate.
Test Number 5) Failure of SES light to go out in the expected time period indicates ECM problem.