Control Unit

NOTE: Electronic Control Module (ECM) may also be referred to as Powertrain Control Module (PCM). This is the same component.

ECM is located under instrument panel, right of steering column.

ECM analyzes all electrical data signals from input devices to control fuel injection, ignition and emissions. ECM includes a back-up fail-safe control system. If a malfunction develops in ECM microcomputer, back-up control system will maintain necessary engine functions to permit operation of vehicle.

PROM is factory-programmed engine calibration data, which modifies ECM for specific transmission, engine, emission, vehicle weight and rear axle ratio application. EEPROM (Electronically Erasable Programmable Read Only Memory) provides fuel delivery back-up so engine runs in case of PROM or ECM failure. Anytime ECM is replaced, install original PROM and/or EEPROM into replacement ECM. If battery voltage is removed, PROM and EEPROM information is retained.