Description and Diagnosis Procedure

SYSTEM: ECM Power Source Circuit

CIRCUIT DESCRIPTION

ECM Main Power Circuit:

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 the terminals + B and + B1 of the ECM.

DIAGNOSTIC PROCEDURE
1. CHECK VOLTAGE OF ECM POWER SOURCE
- If not OK proceed to step 2.
- If OK proceed to "Diagnosis By Symptom".

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. REPLACE "EFI MAIN" RELAY
- 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 (15 AMP) "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.