Infiniti QX56 (JA60). Manual - part 434

EC-388

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ASCD BRAKE SWITCH

ASCD BRAKE SWITCH

Component Description

INFOID:0000000005149464

When the brake pedal is depressed, ASCD brake switch is turned

OFF and stop lamp switch is turned ON. ECM detects the state of

the brake pedal by this input of two kinds (ON/OFF signal).

Refer to 

EC-33

 for the ASCD function.

Diagnosis Procedure

INFOID:0000000005149465

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.

Without CONSULT-III

1. Turn ignition switch ON.

2. Check voltage between ECM terminal 108 and ground under the

following conditions.

OK or NG

OK

>> INSPECTION END.

NG

>> GO TO 2.

2.

CHECK ASCD BRAKE SWITCH POWER SUPPLY CIRCUIT

1. Turn ignition switch OFF.

BBIA0373E

CONDITION

INDICATION

Brake pedal: Slightly depressed

OFF

Brake pedal: Fully released

ON

CONDITION

VOLTAGE

Brake pedal: Slightly depressed

Approximately 0 V

Brake pedal: Fully released

Battery voltage

MBIB0061E

ASCD BRAKE SWITCH

EC-389

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2. Disconnect ASCD brake switch harness connector.

3. Turn ignition switch ON.

4. Check voltage between ASCD brake switch terminal 1 and

ground with CONSULT-III or tester.

OK or NG

OK

>> GO TO 4.

NG

>> GO TO 3.

3.

DETECT MALFUNCTIONING PART

Check the following.

• Harness connectors M31, E152

• Fuse block (J/B) connector M4

• 10 A fuse (No. 15)

• Harness for open or short between ASCD brake switch and fuse

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

4.

CHECK ASCD BRAKE SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1. Turn ignition switch OFF.

2. Disconnect ECM harness connector.

3. Check harness continuity between ECM terminal 108 and ASCD brake switch terminal 2.

Refer to Wiring Diagram.

4. Also check harness for short to ground and short to power.
OK or NG

OK

>> GO TO 5.

NG

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

5.

CHECK ASCD BRAKE SWITCH

Refer to 

EC-390, "Component Inspection"

.

OK or NG

OK

>> GO TO 6.

NG

>> Replace ASCD brake switch.

6.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-35, "How to Check Terminal"

 and 

GI-38, "Intermittent Incident"

.

>> INSPECTION END

BBIA0373E

Voltage: Battery voltage

PBIB0857E

Continuity should exist.

EC-390

< COMPONENT DIAGNOSIS >

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ASCD BRAKE SWITCH

Component Inspection

INFOID:0000000005149466

ASCD BRAKE SWITCH

1. Turn ignition switch OFF.
2. Disconnect ASCD brake switch harness connector.
3. Check harness continuity between ASCD brake switch terminals

1 and 2 under the following conditions.

If NG, adjust ASCD brake switch installation, refer to 

BR-15,

"Inspection and Adjustment"

, and perform step 3 again.

Condition

Continuity

Brake pedal: Fully released

Should exist.

Brake pedal: Slightly depressed

Should not exist.

PBIB1536E

ASCD INDICATOR

EC-391

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ASCD INDICATOR

Component Description

INFOID:0000000005149467

ASCD indicator lamp illuminates to indicate ASCD operation status. Lamp has two indicators, CRUISE and

SET, and is integrated in combination meter.

CRUISE indicator illuminates when MAIN switch on ASCD steering switch is turned ON to indicate that ASCD

system is ready for operation.

SET indicator illuminates when following conditions are met. 

• CRUISE indicator is illuminated.

• SET/COAST switch on ASCD steering switch is turned ON while vehicle speed is within the range of ASCD

setting.

SET indicator remains lit during ASCD control.

Refer to 

EC-33

 for the ASCD function.

Diagnosis Procedure

INFOID:0000000005149468

1.

CHECK OVERALL FUNCTION

Check ASCD indicator under the following conditions.

OK or NG

OK

>> INSPECTION END

NG

>> GO TO 2.

2.

CHECK DTC

Check that DTC UXXXX is not displayed.
OK or NG

OK

>> GO TO 3.

NG

>> Perform trouble diagnosis for DTC UXXXX.

3.

CHECK COMBINATION METER FUNCTION

Refer to 

MWI-5

.

OK or NG

OK

>> GO TO 4.

NG

>> Go to 

MWI-5

.

4.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-35, "How to Check Terminal"

 and 

GI-38, "Intermittent Incident"

.

>> INSPECTION END

ASCD INDICATOR

CONDITION

SPECIFICATION

CRUISE LAMP

• Ignition switch: ON

• MAIN switch: Pressed at the 1st 

time 

→ at the 2nd time

ON 

→ OFF

SET LAMP

• MAIN switch: ON
• When vehicle speed is between 

40 km/h (25 MPH) and 144 km/h 
(89 MPH)

• ASCD:  Operating

ON

• ASCD: Not operating

OFF