Introduction

The Engine Control Module (ECM) monitors several circuit and components to determine if they are functioning properly. If a malfunction is detected in certain circuits the "MALFUNCTION INDICATOR LAMP" (MIL) illuminates to alert the driver that a problem is occuring. The lamp remains illuminated as long the fault is present.

The ECM stores a code in its memory to aid the technician in diagnosis. If the lamp turns off, the fault is no longer present, but the code is stored for 50 attempted engine starts or until the code is cleared from the memory. This aids in diagnosing intermittant problems.