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Ecu Power Source Circuit

  1. Turn ignition off. Remove tilt and telescopic ECU from its mounting, leaving wiring harness connector attached. Turn ignition on. Using a voltmeter, measure voltage by backprobing rear of terminal No. 22 (Violet/Yellow wire) at 22-pin ECU harness connector T9 and terminal No. 3 (White/Black wire) at 12-pin ECU harness connector T8. See Figure. If battery voltage does not exist, go to next step. If battery voltage exists, go to next test listed in SYMPTOM DIAGNOSIS  table under TROUBLE SHOOTING.
  2. Turn ignition off. Using an ohmmeter, measure resistance between ground by backprobing rear of terminal No. 3 (White/Black wire) at 12-pin ECU harness connector T8. If resistance is one k/ohm or less, go to next step. If resistance is more than one k/ohm, repair or replace wiring harness or connector between tilt and telescopic ECU and ground connection. See WIRING DIAGRAMS .
  3. Check continuity of MPX-B fuse (10-amp) located in engine compartment junction block, near left strut tower. If continuity does not exist, check and repair short in wiring harness between MPX-B fuse and all components connected to fuse. See WIRING DIAGRAMS . If continuity exists, check for open in wiring harness between tilt and telescopic ECU and battery. Repair or replace as necessary and retest system operation.
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