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ECM Power Source Circuit (Ignition Keyed)

CAUTION: If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction.
  1. Access ECM behind glove box. Connect Check Harness (SST 09990-01000) between ECM and harness. See USING CHECK HARNESS  under INTRODUCTION. Turn ignition on.
  2. Connect voltmeter negative lead to terminal No. 69 (Brown wire) at ECM "B" connector. Connect voltmeter positive lead to terminal No. 31 (Black/Red wire) at ECM "A" connector. See Figure. If battery voltage is present, ECM keyed (ignition) power circuit is okay. If battery voltage is not present, go to next step.
  3. Check for an open circuit in wiring harness between ground and terminal No. 69 at ECM "B" connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, go to next step.
  4. Measure voltage between chassis ground and terminal No. 1 (Black/Orange wire) at ECM "A" connector. If battery voltage is present, go to step 6). If battery voltage is not present, check the following fuse.
    • AM2 fuse.
  5. If fuse is blown, repair cause of blown fuse. If fuse is okay, check ignition switch. See STEERING COLUMN SWITCHES article in appropriate section. Replace ignition switch as necessary and retest. If ignition switch is okay, repair open circuit between battery and ignition switch, or between ignition switch and ECM.
  6. Turn ignition on. Measure voltage between chassis ground and terminal No. 24 at ECM "A" connector (Black/Blue wire). If battery voltage is not present, replace ECM. If battery voltage is present, check EFI fuse. If EFI fuse is blown, repair cause of blown fuse.
  7. If fuse is okay, check EFI main relay. See RELAYS  under MODULES, MOTORS, RELAYS & SOLENOIDS. If EFI main relay is okay, check circuit between chassis ground and terminal No. 24 at ECM "A" connector. If circuit is okay, repair circuit between battery and EFI fuse.
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