Mazda CX 7. Manual - part 337

ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]

09-02D–5

09-02D

10

INSPECT PCM

• Disconnect the PCM connector.

• Measure the resistance between following 

terminals.
— PCM terminals 1AM and 1AI (part-side)

• Is the resistance 118— 130 ohms?

Yes

Go to the next step.

No

Replace the PCM, then go to the next step.

11

INSPECT INSTRUMENT CLUSTER

• Disconnect the instrument cluster connector.

• Measure the resistance between the 

following terminals.
— Instrument cluster terminals 2R and 2T 

(part-side)

— Instrument cluster terminals 2V and 2X 

(part-side)

• Is the resistance 118— 130 ohms?

Yes

Go to next step.

No

Replace the instrument cluster, then go to the next step.

12

INSPECT INFORMATION DISPLAY

• Disconnect the information display 

connector.

• Measure the resistance between the 

following terminals.

— Information display terminal J and I (part-

side)

• Is the resistance 118— 130 ohms?

Yes

Go to next step.

No

Replace the BCM, then go to the next step.

13

CLASSIFY WIRING HARNESS 
MALFUNCTION OR MODULE MALFUNCTION

• Turn the ignition switch to the LOCK position.

• Disconnect the connector of any unit that 

does not respond. (If there are two or more 
units that do not respond, disconnect only 
one of the units.)

• Turn the ignition switch to the ON position.

• Measure the voltage between the following 

terminals.
— DLC-2 terminals F and GND

— DLC-2 terminals E and GND

— DLC-2 terminals L and GND

— DLC-2 terminals K and GND

• Is voltage 2.0— 3.0 V?

Yes

Go to the next step.

No

Retry this step with other module connector disconnected.
If all units that do not respond are disconnected, go to Step 
15.

STEP

INSPECTION

ACTION

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ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]

09-02D–6

End Of Sie

14

INSPECT WIRING HARNESS OF ANY UNIT 
THAT DOES NOT RESPOND

• Turn the ignition switch to the LOCK position.

• Inspect for continuity between the following 

connector terminals of any disconnected 
unit.

PCM— DLC-2

• 1AM— other terminals

• 1AI— other terminals

TCM— DLC-2

• A14— other terminals

• A6— other terminals

DSC HU/CM— DLC-2

• X— other terminals

• W— other terminals

AWD control module— DLC-2

• G— other terminals

• H— other terminals

BCM— DLC-2

• 3X, 5L— other terminals

• 3W, 5I— other terminals

SAS control module— DLC-2

• 2E— other terminals

• 2F— other terminals

Keyless control module— DLC-2

• 3X— other terminals

• 3W— other terminals

Instrument cluster— DLC-2

• 2R— other terminals

• 2T— other terminals

• 2V— other terminals

• 2X— other terminals

Audio amplifier— DLC-2

• 2O— other terminals

• 2P— other terminals

Climate control unit— DLC-2

• B— other terminals

• A— other terminals

Audio unit— DLC-2

• 1O— other terminals

• 1Q— other terminals

Car-navigation unit— DLC-2

• 1O— other terminals

• 1Q— other terminals

Information display— DLC-2

• J— other terminals

• I— other terminals

• Is there continuity?

Yes

Repair or replace the wiring harness, then go back to Step 
1.

No

Replace the disconnected unit, then go back to Step 1.

15

INSPECT CAN RELATED WIRING HARNESS

• Inspect the related wiring harnesses (CAN_L 

and/or CAN_H) for the short circuit (to power 
supply or ground).

• Is the wiring harness normal?

Yes

Repair or replace the wiring harness, then go back to Step 
1.

No

Go back to Step 1.

STEP

INSPECTION

ACTION

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ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]

09-02D–7

09-02D

DTC TABLE[MULTIPLEX COMMUNICATION SYSTEM]

id0902e6837000

End Of Sie

DTC

Malfunction location

DTC output module

Page

U0073

CAN system communication error

• PCM

• TCM

• DSC HU/CM

• AWD control module

• BCM

• SAS control module

• Keyless control module

• Instrument cluster

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

U0100

Communication error to PCM

• TCM

• DSC HU/CM

• AWD control module

• Keyless control module

• Instrument cluster

 (See 09-02D-8 
PROCEDURES FOR 
DETERMINING THE 
LOCATION OF A 
MALFUNCTION[MULTIPLE
X COMMUNICATION 
SYSTEM].)

U0101

Communication error to TCM

• PCM

• DSC HU/CM

• AWD control module

• Instrument cluster

U0114

Communication error to AWD control module

• DSC HU/CM

• Instrument cluster

U0121

Communication error to DSC HU/CM

• PCM

• TCM

• AWD control module

• Instrument cluster

U0140

Communication error to BCM

• DSC HU/CM

• Keyless control module

• Instrument cluster

Communication error to instrument cluster

TCM

U0151

Communication error to SAS control module

Instrument cluster

U0155

Communication error to instrument cluster

• PCM

• AWD control module

• SAS control module

• Climate control unit

U0164

Communication error to climate control unit

Instrument cluster

U0166

Communication error to climate control unit

Information display

U0181

Communication error to instrument cluster

Information display

U0184

Communication error to audio unit (base 
module)

Information display

U0214

Communication error to keyless control module

Instrument cluster

U0323

Communication error to instrument cluster

Keyless control module

U0415

Abnormal message from DSC HU/CM

TCM

U0516

CAN system communication error

Climate control unit

 (See 09-02D-16 DTC 
U0516, U2516, 
16:Er12[MULTIPLEX 
COMMUNICATION 
SYSTEM].)

U1900

Communication error to other module

DSC HU/CM

 (See 09-02D-8 
PROCEDURES FOR 
DETERMINING THE 
LOCATION OF A 
MALFUNCTION[MULTIPLE
X COMMUNICATION 
SYSTEM].)

U2023

Abnormal message from PCM

• DSC HU/CM

• Keyless control module

U2516

CAN system communication error

• Instrument cluster

• Information display

 (See 09-02D-16 DTC 
U0516, U2516, 
16:Er12[MULTIPLEX 
COMMUNICATION 
SYSTEM].)

16:Er12

CAN system communication error

Audio unit (base module)

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ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]

09-02D–8

PROCEDURES FOR DETERMINING THE LOCATION OF A MALFUNCTION[MULTIPLEX COMMUNICATION 
SYSTEM]

id0902e6830500

System Wiring Diagram

PCM

1. Inspect the display of DTC U0101, U0121 and/or U0155, using the M-MDS.

(See 09-02D-7 DTC TABLE[MULTIPLEX COMMUNICATION SYSTEM].)

2. Referring to the following table, determine the malfunctioning part of the CAN system.

×: Normal

— : Communication error

PCM

BCM

BCM

DSC HU/CM

TCM

: FRONT HARNESS

: EMISSION HARNESS

: INSTRUMENT PANEL HARNESS

SAS 
CONTROL 
MODULE

AWD 
CONTROL 
MODULE

KEYLESS 
CONTROL 
MODULE

INSTRUMENT 
CLUSTER

CLIMATE 
CONTROL 
UNIT

AUDIO 
AMPLIFIER

INSTRUMENT 
CLUSTER

INFORMATION 
DISPLAY

CAR-NAVIGATION 
UNIT OR 
AUDIO UNIT 
(BASE MODULE)

WIRING
HARNESS A

WIRING
HARNESS B

WIRING
HARNESS P

WIRING
HARNESS G

WIRING
HARNESS C

WIRING
HARNESS O

WIRING
HARNESS H

WIRING
HARNESS R

WIRING
HARNESS D

WIRING
HARNESS S

WIRING
HARNESS E

WIRING
HARNESS F

WIRING
HARNESS I

WIRING
HARNESS J

WIRING
HARNESS Q

WIRING
HARNESS K

WIRING
HARNESS L

WIRING
HARNESS M

WIRING
HARNESS N

: REAR HARNESS

acxuuw00002225

Module

Communication status

Malfunction location

TCM

DSC HU/CM

Instrument cluster

PCM

— — — 

• Wiring harness A

• PCM

— 

×

×

• Wiring harness B

• TCM

×

— 

×

• Wiring harness D

• DSC HU/CM

×

— — 

• Wiring harness C

×

×

— 

• Wiring harness E

• BCM

• Wiring harness F

• Wiring harness H

• Wiring harness J

• Wiring harness K

• Wiring harness M

• Instrument cluster

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