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Home › Infiniti › 2003 › I35 › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P1572: ASCD Brake Switch › Diagnostic Procedure

Diagnostic Procedure

  1. If using CONSULT-II, go to next step. If not using CONSULT-II, go to step  3 .
  2. Turn ignition on. Select BRAKE SW1 in DATA MONITOR mode with CONSULT-II. When brake pedal is depressed, CONSULT-II should indicate OFF. When brake pedal is released, CONSULT-II should indicate ON. If operation is as specified, go to step  4 . If operation is not as specified, go to step  5 .
  3. Turn ignition on. Measure voltage between ground and ECM terminal No. 59 (Green/Black wire) by backprobing. See Figure and Figure . When brake pedal is depressed, voltage should be about zero volts. When brake pedal is released, battery voltage should exist. If operation is as specified, go to next step. If operation is not as specified, go to step  5 .
  4. Select BRAKE SW2 in DATA MONITOR mode with CONSULT-II. Without CONSULT-II, measure voltage between ground and ECM terminal No. 55 (Red/Green wire) by backprobing. When brake pedal is released, CONSULT-II should indicate OFF, and voltage should be about zero volts. When brake pedal is depressed, CONSULT-II should indicate ON, and battery voltage should exist. If operation is as specified, go to step  16 . If operation is not as specified, go to step  11 .
  5. Turn ignition off. Disconnect ASCD brake switch harness connector. See Fig 1 . Turn ignition on. Measure voltage between ground and ASCD brake switch harness connector terminal No. 1 (Orange wire). If battery voltage exists, go to step  7 . If battery voltage does not exist, go to next step.
  6. Check the following:
    • Check fuse No. 30 (10-amp) located in fuse block under left side of instrument panel.
    • Check for poor connection at fuse block connector E83 terminal 7H (Orange wire). See Figure .
    • Check for open or short between ASCD brake switch and fuse.
    Repair as necessary.
  7. Turn ignition off. Disconnect ECM harness connector. Check continuity of Green/Black wire between ASCD brake switch harness connector terminal No. 2 and ECM terminal No. 59. Also, check circuit for short to ground and short to voltage. If operation is as specified, go to step  11 . If problem is not found, go to next step .
  8. Check the following:
    • Check for poor connection at White, 18-pin connector F53 terminal No. 2 (Green/Black wire). See Figure . Connector is located near ECM. See Figure .
    • Check for poor connection at Super Multiple Junction (SMJ) connector M15 terminal 4D (Green/Black wire). See Figure . SMJ connector M15 is located under left side of instrument panel. See Figure .
    • Check for open or short between ASCD brake switch and ECM.
    Repair as necessary.
  9. Check continuity between ASCD brake switch terminals. When brake pedal is depressed, continuity should not exist. When brake pedal is released, continuity should exist. If continuity is as specified, go to next step. If continuity is not as specified, replace ASCD brake switch.
  10. Check the following:
    • Check for poor connection at White, 18-pin connector F53 terminal No. 2 (Green/Black wire). See Figure . Connector is located near ECM. See Figure .
    • Check for poor connection at Super Multiple Junction (SMJ) connector M15 terminal 4D (Green/Black wire). See Figure . SMJ connector M15 is located under left side of instrument panel. See Figure .
    • Check for open or short between ASCD clutch switch and ECM.
    Repair as necessary.
  11. Turn ignition off. Disconnect ASCD brake switch harness connector. See Fig 1 . Turn ignition on. Measure voltage between ground and ASCD brake switch harness connector terminal No. 1 (Orange wire). If battery voltage exists, go to step  14 . If battery voltage does not exist, go step  13 .
  12. Check the following:
    • Check fuse No. 20 (15-amp) located in fuse block under left side of instrument panel.
    • Check for poor connection at fuse block connector M17 terminal 11K (Orange wire). See Figure .
    • Check for poor connection at Super Multiple Junction (SMJ) connector M15 terminal 4A (Orange wire). See Figure . SMJ connector M15 is located under left side of instrument panel. See Figure .
    • Check for open or short between stop lamp switch and fuse.
    Repair as necessary.
  13. Disconnect ECM harness connector. Check continuity of Red/Green wire between stop lamp switch harness connector terminal No. 2 and ECM harness connector terminal No. 55. Continuity should exist. Also check harness connector for short to ground and short to power. If problem is found, go to next step. If problem is not found, go to step  15 .
  14. Check the following:
    • Check for poor connection at Super Multiple Junction (SMJ) connector M15 terminal 4D (Green/Black wire). See Figure . SMJ connector M15 is located under left side of instrument panel. See Figure .
    • Check for poor connection at White, 18-pin connector F55 terminal No. 2 (Green/Black wire). See Figure . Connector F55 is located near ECM. See Figure .
    • Check for open or short between ASCD brake switch and ECM.
    Repair as necessary.
  15. Check continuity between stop lamp switch terminals. When brake pedal is depressed, continuity should exist. When brake pedal is released, continuity should not exist. If continuity is as specified, go to next step. If continuity is not as specified, replace stop lamp switch.
  16. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
Fig 1: Locating ASCD Brake Switch & Stop Lamp Switch
G00103826Courtesy of NISSAN MOTOR CO., U.S.A.
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