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Test No. 1: Body Ecu Power Source Circuit: Testing

  1. Check WIP (20-amp), ACC (15-amp), HORN/HAZ (15-amp), POWER (30-amp), MPX-B (15-amp) and ECU-IG fuses (10-amp) located in engine room R/B and driver side J/B. See FUSES & CIRCUIT BREAKERS article for 1999 models or FUSES & CIRCUIT BREAKERS article for 2000 models. If fuses are okay, go to step  2. If fuses are open, replace. See WIRING DIAGRAMS .
  2. Disconnect body ECU harness connectors. Turn ignition on. Measure voltage between WIP (terminal No. 9) and ECU-IG (terminal No. 10) terminals on the body ECU 15 pin (R1) connector and ground. Voltage should be 10-14 volts. Turn ignition off. Measure voltage between HAZ (terminal No. 7) and POWER (terminal No. 3) terminals on the body ECU 15 pin (R1) connector and ground. Voltage should be 10-14 volts. Turn ignition on. Measure voltage between ACC terminal on the harness side of the body ECU 23 pin (B16) connector (terminal No. 9, Gray wire) and ground. Voltage should be 10-14 volts. If voltage is as specified, go to step  3. If voltage is not as specified, check ignition switch, wiring and connectors. See 1999 STEERING COLUMN SWITCHES - TRUCKS or 2000 STEERING COLUMN SWITCHES article.
  3. If ACC voltage is okay, check continuity between GND (terminal No. 8) terminal on the body ECU R1 connector and body ground. If continuity does not exist, repair driver side junction block ground, wiring or connectors. See WIRING DIAGRAMS . If continuity exists, perform pin voltage tests. See PIN VOLTAGE TESTS . If pin voltage tests are not to specification, replace driver side junction block and body ECU assembly. Retest system.
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