Mazda CX 7. Manual - part 342

ON-BOARD DIAGNOSTIC [BCM]

09-02F–3

09-02F

End Of Sie

DTC B1317[BCM]

id0902f5830900

Diagnostic procedure

End Of Sie

C144A

Steering phase C circuit short to 
ground

Short to GND in wiring harness between BCM 
and steering angle sensor

(See 09-02F-24 DTC C1295, 
C1307, C1441, C1442, C1443, 
C1444, C144A, C144C[BCM].)

C1937

Steering wheel angle sensor offset 
failure

BCM lost steering angle initialization position

(See 09-02F-26 DTC 
C1937[BCM].)

U0073

CAN system communication error

BCM or twisted pair malfunction

(See 09-02D-14 DTC 
U0073[MULTIPLEX 
COMMUNICATION SYSTEM].)

DTC 

No.

Description

Detection condition

Page

DTC B1317

Battery voltage high

DETECTION 
CONDITION

Input voltage from the battery is excessively high

POSSIBLE 
CAUSE

• Battery malfunction

• Generator malfunction

• BCM malfunction

STEP

INSPECTION

ACTION

1

INSPECT DTC FROM PCM

• Connect the M-MDS to the DLC-2.

• Are any DTCs from the PCM displayed?

Yes

Perform DTC inspection.
 (See 01-02-13 DTC TABLE[L3 WITH TC].)
Go to the next step.

No

Go to the next step.

2

VERIFY TROUBLESHOOTING COMPLETED

• Make sure to reconnect all disconnected 

connectors.

• Clear the DTC from the BCM memory using 

the M-MDS.

• Turn the ignition switch to LOCK position 

then ON position.

• Is the same DTC present?

Yes

Replace the BCM.
 (See 09-40-1 BODY CONTROL MODULE (BCM) 
REMOVAL/INSTALLATION.)

No

DTC troubleshooting completed.

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ON-BOARD DIAGNOSTIC [BCM]

09-02F–4

DTC B1318[BCM]

id0902f5831000

DTC B1318

Battery voltage low

DETECTION 
CONDITION

Input voltage from the battery is excessively low

POSSIBLE 
CAUSE

• Open circuit in wiring harness between BCM terminal 4I and battery

• Open circuit in wiring harness between BCM terminal 4J and battery

• Open circuit in wiring harness between BCM terminal 1I and battery

• Short to GND in wiring harness between BCM terminal 4I and battery

• Short to GND in wiring harness between BCM terminal 4J and battery

• Short to GND in wiring harness between BCM terminal 1I and battery

• Battery malfunction

• Generator malfunction

• BCM malfunction

+

-

1I

4J

4I

C

E

IGNITION SWITCH WIRING 

HARNESS-SIDE CONNECTOR

BCM WIRING HARNESS-SIDE  

CONNECTOR

IGNITION SWITCH

BCM

BATTERY

A

B

C

D

E

F

1E

1G

1I

1K

1M

1O

1A

1C

1N

1L

1P

1H

1D

1B

1F

1J

4G

4I

4A

4H

4F

4J

4D

4B

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ON-BOARD DIAGNOSTIC [BCM]

09-02F–5

09-02F

Diagnostic procedure

End Of Sie

STEP

INSPECTION

ACTION

1

INSPECT DTC FROM PCM

• Connect the M-MDS to the DLC-2.

• Are any DTCs from the PCM displayed?

Yes

Perform DTC inspection.
 (See 01-02-13 DTC TABLE[L3 WITH TC].)
Go to Step 5.

No

Go to the next step.

2

INSPECT BCM CONNECTOR

• Disconnect the BCM connector.

• Inspect the BCM connector terminals for 

poor connection (such as damaged/pulled-
out pins, and corrosion).

• Is there any malfunction?

Yes

Repair or replace the terminal, then go to Step 5.

No

Go to the next step.

3

INSPECT BCM POWER SUPPLY CIRCUIT 
FOR OPEN CIRCUIT

• Disconnect the negative battery cable.

• Disconnect the positive battery cable.

• Turn the ignition switch to ON.

• Inspect for continuity between following 

terminals:

— BCM terminal 4I (wiring harness-side) —  

battery positive terminal (wiring harness-
side)

— BCM terminal 4J (wiring harness-side) —  

battery positive terminal (wiring harness-
side)

— BCM terminal 1I (wiring harness-side) —  

battery positive terminal (wiring harness-
side)

• Is there continuity?

Yes

Go to the next step.

No

Repair or replace the wiring harness for a possible open 
circuit, then go to Step 5.

4

INSPECT BCM POWER SUPPLY CIRCUIT 
FOR SHORT TO GND

• Inspect for continuity between following 

terminals: 

— BCM terminal 4I (wiring harness-side) —  

body GND

— BCM terminal 4J (wiring harness-side) —  

body GND

— BCM terminal 1I (wiring harness-side) —  

body GND

• Is there continuity?

Yes

Repair or replace the wiring harness for a possible short to 
GND, then go to the next step.

No

Go to the next step.

5

VERIFY TROUBLESHOOTING COMPLETED

• Make sure to reconnect all disconnected 

connectors.

• Clear the DTC from the BCM memory using 

the M-MDS.

• Turn the ignition switch to LOCK position 

then ON position.

• Is the same DTC present?

Yes

Replace the BCM.
 (See 09-40-1 BODY CONTROL MODULE (BCM) 
REMOVAL/INSTALLATION.)

No

DTC troubleshooting completed.

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ON-BOARD DIAGNOSTIC [BCM]

09-02F–6

DTC B1322[BCM]

id0902f5838000

Diagnostic procedure

DTC B1322

Drive door ajar circuit short to ground

DETECTION 
CONDITION

Short to GND in wiring harness between BCM and front door switch (driver-side)

POSSIBLE 
CAUSE

• Short to GND in wiring harness between BCM terminal 5Y and front door switch (driver-side) terminal 

G

• Front door switch malfunction

• BCM malfunction

STEP

INSPECTION

ACTION

1

INSPECT FRONT DOOR SWITCH (DRIVER-
SIDE) CONNECTOR

• Turn the ignition switch off.

• Disconnect the front door switch (driver-side) 

connector.

• Inspect the front door switch (driver-side) 

connector terminals for poor connection 
(such as damaged/pulled-out pins, and 
corrosion).

• Is there any malfunction?

Yes

Repair or replace the terminal, then go to Step 5.

No

Go to the next step.

2

INSPECT BCM CONNECTOR

• Disconnect the BCM connector.

• Inspect the BCM connector terminals for 

poor connection (such as damaged/pulled-
out pins, and corrosion).

• Is there any malfunction?

Yes

Repair or replace the terminal, then go to Step 5.

No

Go to the next step.

3

INSPECT FRONT DOOR SWITCH (DRIVER-
SIDE) SIGNAL CIRCUIT FOR SHORT TO GND

• Inspect for continuity between BCM terminal 

5Y (wiring harness-side) and body GND.

• Is there continuity?

Yes

Repair or replace the wiring harness for a possible open 
circuit, then go to Step 5.

No

Go to the next step.

5Y

A

BCM

A

5Q

5K

5B

5E

5H

5AC

5N

5Z

5T

5W

5G

5D

5A

5O

5AA

5U

5X

5Y

5V

5S

5P

5M

5AD

5AB

5I

5F

5J

5C

5L

5R

FRONT DOOR SWITCH

FRONT DOOR SWITCH WIRING 

HARNESS-SIDE CONNECTOR

BCM WIRING HARNESS-SIDE 

CONNECTOR

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