System Diagnostics: Notes

NOTE: The Malfunction Indicator Light (MIL) may also be referred to as the CHECK ENGINE light.

The self-diagnostic capabilities of this system, if properly utilized, can simplify testing. The Powertrain Control Module (PCM) monitors several different engine control system circuits.

If a problem is sensed with a monitored circuit, PCM memory stores a trouble code, the CHECK ENGINE light glows and PCM enters limp-in mode. In limp-in mode, PCM compensates for component failure by substituting information from other sources. This allows vehicle operation until repairs can be made.

Once codes are known, see TROUBLE CODES table to determine the questionable circuit. Test circuits and repair or replace components as required. If problem is repaired or ceases to exist, the PCM cancels trouble code after 50 ignition on/off cycles. To clear codes, see CLEARING TROUBLE CODES .

A specific trouble code results from a particular system failure. A trouble code does not condemn a specific component. Component is not necessarily the reason for failure. Trouble codes only call out a probable malfunction area.