Engine Controls - ECM Testing Precautions

CLASSIFICATION:
EC95-011

REFERENCE:
NTB95-059

DATE:
June 7, 1995

PRECAUTIONS FOR TESTING/DIAGNOSING THE ECCS SYSTEM TO AVOID DAMAGING THE ECM

APPLIED VEHICLE(S): All

SERVICE INFORMATION

Observing the following precautions when testing/diagnosing the Electronic Concentrated Control System (ECCS) may help prevent damaging the Electronic Control Module (ECM).

SERVICE PROCEDURE

1. Most relays in the ECCS system (Fuel pump, A/C, etc.) and actuators (Injectors, etc.) are powered by the battery. The ECM controls the relay or actuator by supplying the ground.




DO NOT apply battery voltage directly to any of the ECM pins (or wires connected to them) which supply the ground to any relays or actuators (see circled areas in illustration). Doing so will permanently damage the ECM.

2. Do not connect or disconnect any ECCS connectors when the ignition key is in the "ON" position.

3. Do not remove the cover of the ECM.