ASCD Brake/Stoplight Switch Check

Turn ignition switch to LOCK position. Disconnect ASCD control unit harness connector. Turn ignition switch to RUN position. Turn ASCD main switch on. Measure voltage at terminal No. 5 (Blue/Yellow wire) at ASCD control unit harness connector. See Figure . When brake pedal is depressed or gear selector lever is in "P" or "N" position, zero volts should exist. When brake pedal is released and gear selector lever is in any position other than "P" or "N", battery voltage should exist. If voltage is as specified, go to next step. If voltage is not as specified, check for the following and repair as necessary:
- Faulty ASCD brake switch. See SWITCHES under COMPONENT TESTS.
- Faulty inhibitor switch. See SWITCHES under COMPONENT TESTS.
- Faulty ASCD hold relay. See WIRING DIAGRAMS .
- Open or short in harness. See WIRING DIAGRAMS .
Measure voltage at terminal No. 11 (Green/Yellow wire) at ASCD control unit harness connector. When brake pedal is depressed, battery voltage should exist. When brake pedal is released, zero volts should exist. If voltage is as specified, ASCD brake/stoplight switch is okay at this time. If voltage is not as specified, check for the following and repair as necessary:
- Faulty fuse No. 20 (10-amp) in instrument panel fuse box.
- Open or short in harness between ASCD control unit and stoplight switch. See WIRING DIAGRAMS .
- Faulty stoplight switch. See SWITCHES under COMPONENT TESTS.