System Diagnostics: Notes

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

Self-diagnostic capabilities of this system, if properly used, can simplify testing. 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, MIL 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.

Test circuits and repair or replace components as required. If problem is repaired or ceases to exist, PCM cancels trouble code after 50 ignition on/off cycles.

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