LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Infiniti >> 2008 >> G35 Base >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine Control System - DTCS P0850 Through P2A03 >> DTC P1572: ICC Brake Switch >> Diagnosis Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnosis Procedure

  1. CHECK OVERALL FUNCTION-I

    With CONSULT-III 

    1. Turn ignition switch ON.
    2. Select "BRAKE SW1" in "DATA MONITOR" mode with CONSULT-III.
    3. Check "BRAKE SW1" indication under the following conditions.
      DATA MONITOR

      Monitor item Condition Indication
      BRAKE SW1 Brake pedal (A/T)
      Brake pedal and clutch pedal (M/T)      		 Slightly depressed OFF
      Fully released ON

    Without CONSULT-III 

    1. Turn ignition switch ON.
    2. Check the voltage between ECM harness connector and ground.
      TERMINALS VOLTAGE REFERENCE

      ECM Ground Condition Voltage
      Connector Terminal
      M107 126 (ICC brake switch signal) Ground Brake pedal (A/T)
      Brake pedal and clutch pedal (M/T)      		 Slightly depressed Approx. 0V
      Fully released Battery voltage

    Is the inspection result normal? 

    YES: GO TO 2.

    NO-1: A/T models: GO TO  3.

    NO-2: M/T models: GO TO  8.

  2. CHECK OVERALL FUNCTION-II

    With CONSULT-III 

    Select "BRAKE SW2" and check indication under the following conditions.

    BRAKE SW2 REFERENCE

    Monitor item Condition Indication
    BRAKE SW2 Brake pedal Slightly depressed ON
    Fully released OFF

    Without CONSULT-III 

    Check the voltage between ECM harness connector and ground.

    TERMINALS VOLTAGE REFERENCE

    ECM Ground Condition Voltage
    Connector Terminal
    M107 122 (Stop lamp switch signal) Ground Brake pedal Slightly depressed Battery voltage
    Fully released Approx. 0V

    Is the inspection result normal? 

    YES: GO TO  22.

    NO: GO TO  16.

  3. CHECK ICC BRAKE SWITCH POWER SUPPLY CIRCUIT
    1. Turn ignition switch OFF.
    2. Disconnect ICC brake switch harness connector.
    3. Turn ignition switch ON.
    4. Check the voltage between ICC brake switch harness connector and ground.
      TERMINALS VOLTAGE REFERENCE

      ICC brake switch Ground Voltage
      Connector Terminal
      E114 1 Ground Battery voltage

    Is the inspection result normal? 

    YES: GO TO  5.

    NO: GO TO 4.

  4. DETECT MALFUNCTIONING PART

    Check the following.

    • Fuse block (J/B) connector E103
    • 10A fuse (No. 3)
    • Harness for open or short between ICC brake switch and fuse

      Repair open circuit or short to ground in harness or connectors.

  5. CHECK ICC BRAKE SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT-II
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check the continuity between ICC brake switch harness connector and ECM harness connector.
      TERMINALS CONTINUITY REFERENCE

      ICC brake switch ECM Continuity
      Connector Terminal Connector Terminal
      E114 2 M107 126 Existed
    4. Also check harness for short to ground and short to power.

    Is the inspection result normal? 

    YES: GO TO  7.

    NO: GO TO 6.

  6. DETECT MALFUNCTIONING PART

    Check the following.

    • Harness connectors E106, M6
    • Harness for open or short between ICC brake switch and ECM

      Repair open circuit or short to ground or short to power in harness or connectors.

  7. CHECK ICC BRAKE SWITCH

    Refer to "COMPONENT INSPECTION (ICC BRAKE SWITCH) ".

    Is the inspection result normal? 

    YES: GO TO  22.

    NO: Replace ICC brake switch.

  8. CHECK ICC BRAKE SWITCH CIRCUIT
    1. Turn ignition switch OFF.
    2. Disconnect ICC clutch switch harness connector.
    3. Turn ignition switch ON.
    4. Check the voltage between ICC clutch switch harness connector and ground.
      TERMINALS VOLTAGE REFERENCE

      ICC clutch switch Ground Condition Voltage
      Connector Terminal
      E113 2 Ground Brake pedal Slightly depressed Approx. 0V
      Fully released Battery voltage

    Is the inspection result normal? 

    YES: GO TO  13.

    NO: GO TO 9.

  9. CHECK ICC BRAKE SWITCH POWER SUPPLY CIRCUIT
    1. Turn ignition switch OFF.
    2. Disconnect ICC brake switch harness connector.
    3. Turn ignition switch ON.
    4. Check the voltage between ICC brake switch harness connector and ground.
      TERMINALS VOLTAGE REFERENCE

      ICC brake switch Ground Voltage
      Connector Terminal
      E114 1 Ground Battery voltage

    Is the inspection result normal? 

    YES: GO TO  11.

    NO: GO TO 10.

  10. DETECT MALFUNCTIONING PART

    Check the following.

    • Fuse block (J/B) connector E103
    • 10A fuse (No. 3)
    • Harness for open or short between ICC brake switch and fuse

      Repair open circuit or short to ground in harness or connectors.

  11. CHECK ICC BRAKE SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
    1. Turn ignition switch OFF.
    2. Check the continuity between ICC brake switch harness connector and ICC clutch switch harness connector.
      TERMINALS CONTINUITY REFERENCE

      ICC brake switch ICC clutch switch Continuity
      Connector Terminal Connector Terminal
      E114 2 E113 2 Existed
    3. Also check harness for short to ground and short to power.

    Is the inspection result normal? 

    YES: GO TO 12.

    NO: Repair open circuit or short to ground or short to power in harness or connectors.

  12. CHECK ICC BRAKE SWITCH

    Refer to "COMPONENT INSPECTION (ICC BRAKE SWITCH) ".

    Is the inspection result normal? 

    YES: GO TO  22.

    NO: Replace ICC brake switch.

  13. CHECK ICC BRAKE SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check the continuity between ICC clutch switch harness connector and ECM harness connector.
      TERMINALS CONTINUITY REFERENCE

      ICC clutch switch ECM Continuity
      Connector Terminal Connector Terminal
      E113 1 M107 126 Existed
    4. Also check harness for short to ground and short to power.

    Is the inspection result normal? 

    YES: GO TO  15.

    NO: GO TO 14.

  14. DETECT MALFUNCTIONING PART

    Check the following.

    • Harness connectors E106, M6
    • Harness for open or short between ICC clutch switch and ECM

      Repair open circuit or short to ground or short to power in harness or connectors.

  15. CHECK ICC CLUTCH SWITCH

    Refer to "COMPONENT INSPECTION (ICC CLUTCH SWITCH) ".

    Is the inspection result normal? 

    YES: GO TO  22.

    NO: Replace ICC clutch switch.

  16. CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT
    1. Turn ignition switch OFF.
    2. Disconnect stop lamp switch harness connector.
    3. Disconnect ICC brake hold relay harness connector.
    4. Check the voltage between stop lamp switch harness connector and ground.
      TERMINALS VOLTAGE REFERENCE

      Stop lamp switch Ground Voltage
      Connector Terminal
      E110 1 Ground Battery voltage
    5. Check the voltage between ICC brake hold relay harness connector and ground.
      TERMINALS VOLTAGE REFERENCE

      ICC brake hold relay Ground Voltage
      Connector Terminal
      E51 3 Ground Battery voltage

    Is the inspection result normal? 

    YES: GO TO  18.

    NO: GO TO 17.

  17. DETECT MALFUNCTIONING PART

    Check the following.

    • Fuse block (J/B) connector E103
    • 10A fuse (No. 7)
    • Harness for open or short between battery and stop lamp switch
    • Harness for open or short between battery and ICC brake hold relay

      Repair open circuit or short to ground in harness or connectors.

  18. CHECK STOP LAMP SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
    1. Disconnect ECM harness connector.
    2. Check the continuity between stop lamp switch harness connector and ECM harness connector.
      TERMINALS CONTINUITY REFERENCE

      Stop lamp switch ECM Continuity
      Connector Terminal Connector Terminal
      E110 2 M107 122 Existed
    3. Check the continuity between ICC brake hold relay harness connector and ECM harness connector.
      TERMINALS CONTINUITY REFERENCE

      ICC brake hold relay ECM Continuity
      Connector Terminal Connector Terminal
      E51 5 M107 122 Existed
    4. Also check harness for short to ground and short to power.

    Is the inspection result normal? 

    YES: GO TO  20.

    NO: GO TO 19.

  19. DETECT MALFUNCTIONING PART

    Check the following.

    • Fuse block (J/B) connector E103, M2
    • Harness for open or short between ECM and stop lamp switch
    • Harness for open or short between ECM and ICC brake hold relay

      Repair open circuit or short to ground or short to power in harness or connectors.

  20. CHECK STOP LAMP SWITCH

    Refer to "COMPONENT INSPECTION (STOP LAMP SWITCH) ".

    Is the inspection result normal? 

    YES: GO TO 21.

    NO: Replace stop lamp switch.

  21. CHECK ICC BRAKE HOLD RELAY

    Refer to "COMPONENT INSPECTION (ICC BRAKE HOLD RELAY) ".

    Is the inspection result normal? 

    YES: GO TO 22.

    NO: Replace ICC brake hold relay.

  22. CHECK INTERMITTENT INCIDENT

    Refer to "INTERMITTENT INCIDENT ".

    INSPECTION END

scientia non olet · About LEMON Manuals