Logic Module

The logic module is a digital computer containing a microprocessor. The module receives input signals from various switches and sensors. It then computes the fuel injector pulse width, spark advance, ignition coil dwell, idle speed, purge cycle, alternator field control, feedback control, and boost level from this information. The logic module tests many of its own input and output circuits. If a fault is found in a major system, this information is stored in the logic module.

Limp in mode is the attempt by the logic module to compensate for the failure of certain components by substituting information from other sources. If the logic module senses incorrect data or no data at all from the MAP sensor, throttle position sensor, charge temperature sensor or coolant temperature sensor, or the battery voltage sensor, the system is placed into "Limp In Mode" and the power loss light on the instrument panel comes on.