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Home › Infiniti › 2001 › Q45 Base › Repair and Diagnosis › Transmission › Automatic Trans › Shift Interlock Systems › Symptom Tests › Symptom No. 1 › Diagnostic Procedure

Diagnostic Procedure

  1. Access Shift Lock Control Unit (SLCU). See Figure . Ensure ignition is off. Measure voltage between SLCU harness connector terminal No. 1 and ground. See Figure . If battery voltage exists, go to next step. If battery voltage does not exist, check the following items and repair as necessary:
    • Check for open or short in circuit between battery and SLCU harness connector terminal No. 1.
    • Check for blown fuse No. 26 (20-amp).
  2. Turn ignition off. Measure voltage between SLCU harness connector terminal No. 5 and ground with ignition off and on. See Figure . No voltage should exist with ignition off, and battery voltage should exist with ignition on. If voltage is as specified, go to next step. If voltage is not as specified, check the following items and repair as necessary:
    • Check for open or short in circuit between battery and SLCU harness connector terminal No. 5.
    • Check for blown fuse No. 17 (10-amp).
    • Check ignition switch. See appropriate STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.
  3. Turn ignition off. Disconnect SLCU connector. Check for continuity between SLCU harness connector terminal No. 7 and ground. See Figure . If continuity exists, go to next step. If continuity does not exist, repair open in circuit or connector.
  4. Reconnect SLCU connector. Remove key from ignition switch. Access A/T device. See Figure . Measure voltage between A/T device harness connector terminal No. 5 and ground. See Figure . If no voltage exists, go to next step. If voltage exists, check key switch. See KEY SWITCH  under COMPONENT TESTS. Repair as necessary.
  5. Insert key into ignition switch. Measure voltage between A/T device harness connector terminal No. 5 and ground. See Figure . If battery voltage exists, go to next step. If battery voltage does not exist, check the following items and repair as necessary:
    • Check for open or short in circuit between A/T device harness connector terminal No. 5 and key lock switch harness connector terminal No. 4.
    • Check for open or short in circuit between key lock switch harness connector terminal No. 3 and fuse No. 28 (10-amp).
    • Check key switch. See KEY SWITCH  under COMPONENT TESTS.
  6. Turn ignition on, engine off. Ensure selector lever is in "P" position and selector lever button is released. Measure voltage between SLCU harness connector terminal No. 4 and ground. See Figure . If no voltage exists, go to next step. If voltage exists, check detention switch. See DETENTION SWITCH  under COMPONENT TESTS. Replace as necessary.
    7. NOTE: When selector lever cannot be moved from "P" position with brake pedal depressed, push shift lock release knob.
  7. Turn ignition on, engine off. With selector lever in "P" position, depress brake pedal. Push selector lever button. Measure voltage between SLCU harness connector terminal No. 4 and ground. See Figure . Battery voltage should exist. Move selector lever to any other position. Battery voltage should still exist. If voltage is as specified, go to next step. If voltage is not as specified, check the following items and repair as necessary:
    • Check for open or short in circuit between SLCU harness connector terminal No. 4 and A/T device harness connector terminal No. 6.
    • Check for open or short in circuit between A/T device harness connector terminal No. 5 and key switch harness connector terminal No. 4.
    • Check detention switch. See DETENTION SWITCH  under COMPONENT TESTS.
  8. Turn ignition off. Place selector lever in "P" position. Measure voltage between A/T device harness connector terminal No. 8 and ground while depressing and releasing brake pedal. See Figure . With brake pedal depressed, battery voltage should exist. With brake pedal released, no voltage should exist. If voltage is as specified, go to next step. If voltage is not as specified, check the following items and repair as necessary:
    • Check for open or short in circuit between A/T harness connector terminal No. 8 and stoplight switch harness connector terminal No. 2.
    • Check for open or short in circuit between stoplight switch harness connector terminal No. 1 and fuse No. 37 (15-amp).
    • Check stoplight switch. See STOPLIGHT SWITCH  under COMPONENT TESTS.
  9. Turn ignition on, engine off. Measure voltage between SLCU harness connector terminal No. 6 and ground while depressing and releasing brake pedal. See Figure . With brake pedal depressed, battery voltage should exist. With brake pedal released, no voltage should exist. If voltage is as specified, go to next step. If voltage is not as specified, check the following items and repair as necessary:
    • Check for open or short in circuit between SLCU harness connector terminal No. 6 and A/T device harness connector terminal No. 9.
    • Check shift lock solenoid. See SHIFT LOCK SOLENOID  under COMPONENT TESTS.
  10. Check shift lock system operation. See SYSTEM OPERATION CHECK  under TROUBLE SHOOTING. If system is not functioning properly, perform control unit input/output signal test. See SHIFT LOCK CONTROL UNIT  under PIN VOLTAGE TESTS. Repair as necessary.
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