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Home › Infiniti › 1997 › QX4 › Repair and Diagnosis › Accessories & Equipment › Cruise Control Systems › System Tests › Diagnostic Procedure 4: ASCD Brake/Stoplight Switch Check

Diagnostic Procedure 4: ASCD Brake/Stoplight Switch Check

  1. Check ASCD Brake Switch Circuit  - Turn ignition off. Disconnect ASCD control unit harness connector. Turn ignition on. Turn ASCD main switch on. Using a DVOM, measure voltage between ground and ASCD control unit harness connector terminal No. 5 (Blue/Yellow wire). Depress brake pedal. Place gear selector lever in "P" or "N" position. Zero volts should be present. Release brake pedal. Battery voltage should be present with gear selector lever in any position other than "P" or "N". If operation is as specified, go to next step. If operation is not as specified, go to step 3).
  2. Check Stoplight Switch Circuit  - Turn ignition off. Disconnect ASCD control unit harness connector. Turn ignition on. Using a DVOM, measure voltage between ground and ASCD control unit harness connector terminal No. 11 (Green/Yellow wire). With brake pedal depressed, battery voltage should be present. Zero volts should be present with brake pedal released. If operation is as specified, ASCD brake/stoplight switch is okay. If operation is not as specified, go to step 4).
  3. 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.
  4. Check For The Following And Repair As Necessary: 
    • Faulty fuse No. 20 (10-amp), located in fuse block.
    • Open or short in harness between ASCD control unit and stoplight switch.
    • Faulty stoplight switch. See SWITCHES  under COMPONENT TESTS.
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