Infiniti FX35, FX50 (S51). Manual - part 359

CCS-256

< DTC/CIRCUIT DIAGNOSIS >

[DCA]

C1A21 UNIT HIGH TEMP

>> WORK END

CCS

C1A22 BCU CIRCUIT

CCS-257

< DTC/CIRCUIT DIAGNOSIS >

[DCA]

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C1A22 BCU CIRCUIT

Description

INFOID:0000000005501855

• The brake booster control unit receives the brake fluid pressure command signal from ICC sensor integrated

unit via ITS communication and activates the booster solenoid to operate the brake booster. 

• The brake booster adjusts the brake fluid pressure by driving the booster solenoid. 
• The brake pedal is controlled when the brake booster adjusts the brake fluid pressure. 

DTC Logic

INFOID:0000000005501856

DTC DETECTION LOGIC

NOTE:
If DTC “C1A22” is detected along with DTC “U1000”, first diagnose the DTC “U1000”. Refer to 

CCS-313, "ICC

SENSOR INTEGRATED UNIT : DTC Logic"

. 

DTC CONFIRMATION PROCEDURE

1.

PERFORM DTC CONFIRMATION PROCEDURE

1.

Start the engine.

2.

Turn the DCA system ON. 

3.

Perform “All DTC Reading” with CONSULT-III. 

4.

Check if the “C1A22” is detected as the current malfunction in self-diagnosis results of “ICC”. 

Is “C1A22” detected as the current malfunction?

YES

>> Refer to 

CCS-257, "Diagnosis Procedure"

.

NO

>> Refer to 

GI-36, "Intermittent Incident"

. 

Diagnosis Procedure

INFOID:0000000005501857

1.

CHECK SELF-DIAGNOSIS RESULTS

Check if “C1A05” or “U1000” is detected other than “C1A22” in “Self Diagnostic Result” of “ICC”. 
Is any DTC detected?

YES

>> Perform diagnosis on the detected DTC and repair or replace the malfunctioning parts. Refer to

CCS-341, "DTC Index"

.

NO

>> GO TO 2.

2.

CHECK STOP LAMP SWITCH AND ICC BRAKE SWITCH

Check that “STOP LAMP SW” and “BRAKE SW” operate normally in “DATA MONITOR” of “ICC”. 
Is the inspection result normal?

YES

>> GO TO 10.

NO-1

>> When “BRAKE SW” operation is malfunctioning: GO TO 3.

NO-2

>> When “STOP LAMP SW” operation is malfunctioning: GO TO 5.

3.

CHECK ICC BRAKE SWITCH INSTALLATION

1.

Turn the ignition switch OFF.

2.

Check ICC brake switch for correct installation. Refer to 

BR-7, "Inspection and Adjustment"

. 

DTC

(On board 

display)

Trouble diagnosis name

DTC detecting condition

Possible causes

C1A22

(22)

BCU CIRCUIT

If the brake booster control unit cannot control 
the brake booster

• Stop lamp switch circuit
• ICC brake switch circuit
• Stop lamp switch
• ICC brake switch
• Incorrect stop lamp switch installation
• Incorrect ICC brake switch installa-

tion

• ECM
• Brake booster control unit

CCS-258

< DTC/CIRCUIT DIAGNOSIS >

[DCA]

C1A22 BCU CIRCUIT

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Adjust ICC brake switch installation. Refer to 

BR-7, "Inspection and Adjustment"

. 

4.

ICC BRAKE SWITCH INSPECTION

1.

Disconnect ICC brake switch connector. 

2.

Check ICC brake switch. Refer to 

CCS-222, "Component Inspection (ICC Brake Switch)"

. 

Is the inspection result normal?

YES

>> GO TO 7.

NO

>> Replace the ICC brake switch. 

5.

CHECK STOP LAMP FOR ILLUMINATION

Check stop lamp illumination. 
Is the inspection result normal?

YES

>> GO TO 6.

NO

>> Check the stop lamp circuit, and repair or replace the malfunctioning parts. 

6.

CHECK ICC BRAKE HOLD RELAY

1.

Turn the ignition switch OFF.

2.

Remove ICC brake hold relay. 

3.

Check for continuity between ICC brake hold relay terminals. 

Is the inspection result normal?

YES

>> GO TO 7.

NO

>> Replace ICC brake hold relay. 

7.

CHECK HARNESS BETWEEN ECM AND ICC BRAKE HOLD RELAY

1.

Disconnect ECM connector. 

2.

Check for continuity between the ECM harness connector and ICC brake hold relay harness connector. 

VQ35HR

VK50VE

3.

Check for continuity between ECM harness connector and ground. 

VQ35HR

VK50VE

Is the inspection result normal?

ICC brake hold relay

Continuity

Terminal

3

4

Existed

7

6

Not existed

ECM

ICC brake hold relay

Continuity

Connector

Terminal

Connector

Terminal

M107

122

E91

6

Existed

ECM

ICC brake hold relay

Continuity

Connector

Terminal

Connector

Terminal

M160

110

E91

6

Existed

ECM

Ground

Continuity

Connector

Terminal

M107

122

Not existed

ECM

Ground

Continuity

Connector

Terminal

M160

110

Not existed

CCS

C1A22 BCU CIRCUIT

CCS-259

< DTC/CIRCUIT DIAGNOSIS >

[DCA]

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YES

>> GO TO 8.

NO

>> Repair the harnesses or connectors.

8.

CHECK HARNESS BETWEEN ECM AND ICC BRAKE SWITCH

1.

Check for continuity between the ECM harness connector and ICC brake switch harness connector. 

VQ35HR

VK50VE

2.

Check for continuity between ECM harness connector and ground. 

VQ35HR

VK50VE

Is the inspection result normal?

YES

>> GO TO 9.

NO

>> Repair the harnesses or connectors.

9.

CHECK HARNESS BETWEEN ICC BRAKE SWITCH AND ICC BRAKE HOLD RELAY

1.

Disconnect ICC brake switch connector. 

2.

Check for continuity between ICC brake switch harness connector and ICC brake hold relay harness con-
nector. 

3.

Check for continuity between ICC brake switch harness connector and ground. 

Is the inspection result normal?

YES

>> GO TO 10.

NO

>> Repair the harnesses or connectors.

10.

PERFORM SELF-DIAGNOSIS OF ECM

1.

Connect all connectors again if the connectors are disconnected. 

2.

Turn the ignition switch ON.

3.

Perform “All DTC Reading”. 

4.

Check if any DTC is detected in “Self Diagnostic Result” of “ENGINE”. 

Is any DTC detected?

ECM

ICC brake switch

Continuity

Connector

Terminal

Connector

Terminal

M107

126

E114

2

Existed

ECM

ICC brake switch

Continuity

Connector

Terminal

Connector

Terminal

M160

117

E114

2

Existed

ECM

Ground

Continuity

Connector

Terminal

M107

126

Not existed

ECM

Ground

Continuity

Connector

Terminal

M160

117

Not existed

ICC brake switch

ICC brake hold relay

Continuity

Connector

Terminal

Connector

Terminal

E114

1

E91

4

Existed

ICC brake switch

Ground

Continuity

Connector

Terminal

E114

1

Not existed