Circuit Description and Diagnostic Chart

SYSTEM: Engine Control Module (ECM) Power Source Circuit

WIRING DIAGRAM





CIRCUIT DESCRIPTION

When the ignition switch is turned on, battery positive voltage is applied to the coil, closing the contacts of the EFI main relay and supplying power to terminal +B of the ECM.

DIAGNOSTIC PROCEDURE
1. Check voltage of ECM power source.
^ If OK, proceed to next circuit inspection shown on matrix chart in Diagnosis By Symptom in "Powertrain Management Testing Procedures".
Testing and Inspection
^ If not OK, proceed to step 2.

2. Check continuity between terminal E1 and body ground
^ If OK proceed to step 3.
^ If not OK, repair or replace harness or connector.

3. Check EFI Main relay.
^ If OK proceed to step 4.
^ If not OK, replace EFI Main relay.

4. Check IGN fuse.
^ If OK proceed to step 5.
^ If not OK, check for short in all the harness and components connected to IGN fuse.

5. Check ignition switch.
^ If OK proceed to step 6.
^ If not OK, replace ignition switch.

6. Check for open in harness and connector between ignition switch and EFI Main relay; EFI Main relay and body ground.
^ If OK proceed to step 7.
^ If not OK, repair or replace harness or connector.

7. Check EFI fuse.
^ If OK, check for open in harness and connector between EFI Main relay and battery, EFI Main relay and ECM.
^ If not OK, check for short in all the harness and components connected to EFI fuse.