Mazda CX-9 Grand Touring. Manual - part 124

DTC C1446 [DSC/RSC] DIAGNOSTIC PROCEDURE

STEP

INSPECTION

ACTION

1

VERIFY OPEN OR SHORT CIRCUIT 
IN BRAKE SWITCH SIGNAL  



Turn the ignition switch to the ON 
position.  



Measure the voltage between the 
PCM terminal 1T and body ground 
when the brake pedal is depressed 
and released: 

Voltage  

Brake pedal depressed: B+  

Brake pedal released:  

1 V or less  

Yes Go to Step 5.

No

If it is B+ under any condition, then go to the next 

step. If it is 1 V or less under any condition, then 

go to Step 3.

2

INSPECT BRAKE SWITCH SIGNAL 
FOR SHORT TO POWER SUPPLY 
CIRCUIT  



Disconnect the brake switch 
connector.  



Measure the voltage between the 
brake switch connector terminal D 
(vehicle harness-side) and body 
ground.  



Is the voltage 1 V or less ?  

Yes Go to Step 4.

No

Repair or replace the wiring harness between the 

PCM and brake switch, then go to Step 5

3

INSPECT BRAKE SWITCH SIGNAL 
FOR OPEN CIRCUIT  



Disconnect the PCM connectors.  



Disconnect the brake switch 
connector.  



Inspect continuity between the PCM 
connector terminal 1T (vehicle 
harness-side) and brake switch 
terminal D:  



Is there continuity?  

Yes Go to the next step.

No

Repair or replace the wiring harness between the 

PCM and brake switch, then go to Step 5.

INSPECT BRAKE SWITCH  



Inspect the brake switch. 

Yes Go to the next step.

 

2008 Mazda CX-9 Grand Touring 

2008 BRAKES On-Board Diagnostic (DSC/RSC) - Mazda CX-9

  

Microsoft 

 

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DTC C1963 [DSC/RSC] 

DTC C1963 [DSC/RSC] DETECTION CONDITION AND POSSIBLE CAUSE 

DIAGNOSTIC PROCEDURE 

DTC C1963 [DSC/RSC] DIAGNOSTIC PROCEDURE 

4

(See BRAKE SWITCH 
INSPECTION .) 



Is the brake switch normal?  

No

Replace the brake switch, then go to the next step.

(See BRAKE PEDAL 

REMOVAL/INSTALLATION .)

5

VERIFY THAT THE SAME DTC IS 
NOT PRESENT  



Reconnect all disconnected 
connectors.  



Clear the DTCs from the memory. 

(See ON-BOARD DIAGNOSTIC 
[DSC/RSC].) 



Are the same DTCs present?  

Yes

Repeat the inspection from Step 1. 
If the malfunction recurs, replace the DSC/RSC 
HU/CM, then go to the next step. 
(See DSC/RSC HU/CM 
REMOVAL/INSTALLATION .)

No

Go to the next step.

6

VERIFY THAT NO OTHER DTCS 
ARE PRESENT  



Are any other DTCs output?  

Yes

Go to the applicable DTC inspection. 
(See ON-BOARD DIAGNOSTIC [DSC/RSC].)

No

DTC troubleshooting completed.

NOTE:



The initial point of the combined sensor (yaw rate sensor part) is corrected 
based on the signals from each sensor while the vehicle is driven straight, 
however, the correction cannot be performed if the vehicle is continuously 
driven on a curve and DTC C1963 is detected.  

DTC C1963

Combined sensor (Yaw rate sensor part) initial point correction error

DETECTION 

CONDITION 



When a difference occurs between the estimated yaw rate value which is 
calculated by each sensor and the yaw rate value which is detected by the 
combined sensor (yaw rate sensor part).  

POSSIBLE 

CAUSE 



It occurs since the initial point correction for the combined sensor (yaw rate 
sensor part) cannot be performed due to the vehicle being continuously driven 
on a curve, and does not indicate an DSC/RSC system malfunction.  

STEP

INSPECTION

ACTION

PERFORM INITIALIZATION 
PROCEDURE  



Perform the initialization 

 

2008 Mazda CX-9 Grand Touring 

2008 BRAKES On-Board Diagnostic (DSC/RSC) - Mazda CX-9

  

Microsoft 

 

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Page 38 

© 2005 Mitchell Repair Information Company, LLC. 

DTC C1991 [DSC/RSC] 

DTC C1991 [DSC/RSC] DETECTION CONDITION AND POSSIBLE CAUSE 

DIAGNOSTIC PROCEDURE 

DTC C1991 [DSC/RSC] DIAGNOSTIC PROCEDURE 

1

procedure for the combined 
sensor. 

(See DSC/RSC SENSOR 
INITIALIZATION 
PROCEDURE .) 

After the initialization procedure for the combined 
sensor has been completed, go to the next step.

2

VERIFY DTC 
TROUBLESHOOTING 
COMPLETED  



Clear the DTC from the memory. 

(See ON-BOARD 
DIAGNOSTIC [DSC/RSC].) 



Start the engine and drive the 
vehicle at 72 km/h {45 mph} or 
more.  



Is the same DTC present?  

Yes

Repeat the inspection from Step 1. 
If the malfunction occurs again, replace the 
DSC/RSC HU/CM, then go to the next step. 
(See DSC/RSC HU/CM 
REMOVAL/INSTALLATION .)

No

Go to the next step.

3

VERIFY AFTER REPAIR 
PROCEDURE  



Are any other DTCs present?  

Yes

Go to the applicable DTC inspection. 
(See ON-BOARD DIAGNOSTIC [DSC/RSC].)

No

DTC troubleshooting completed.

DTC C1991

DSC/RSC sensor (abnormal initialization) system

DETECTION 

CONDITION 



The DSC/RSC sensor detects that the initialization procedure has not 
been performed.  

POSSIBLE CAUSE 



The initialization procedure for the DSC/RSC sensor has not been 
performed.  

STEP

INSPECTION

ACTION

1

VERIFY INITIALIZATION 
PROCEDURE.  



Has the DSC/RSC sensor 
initialization procedure been 
performed?  

Yes Go to the next step.

No

Perform the DSC/RSC sensor initialization procedure, 

then go to the next step. (See DSC/RSC SENSOR 

INITIALIZATION PROCEDURE .)

VERIFY DTC 

 

2008 Mazda CX-9 Grand Touring 

2008 BRAKES On-Board Diagnostic (DSC/RSC) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 9:50:13 AM

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© 2005 Mitchell Repair Information Company, LLC. 

DTC U1901 [DSC/RSC] 

DTC U1901 [DSC/RSC] DETECTION CONDITION AND POSSIBLE CAUSE 

2

TROUBLESHOOTING 
COMPLETED  



Clear the DTC from the 
memory. 

(See ON-BOARD 
DIAGNOSTIC 
[DSC/RSC].) 



Is the same DTC present?  

Yes

Repeat the inspection from Step 1. 
If the malfunction occurs again, replace the DSC/RSC 
HU/CM, then go to the next step. 
(See DSC/RSC HU/CM 
REMOVAL/INSTALLATION .)

No

Go to the next step.

3

VERIFY AFTER REPAIR 
PROCEDURE  



Are any other DTCs present? 

Yes

Go to the applicable DTC inspection. 
(See ON-BOARD DIAGNOSTIC [DSC/RSC].)

No

DTC troubleshooting completed.

DTC U1901

Combined sensor system (CAN2 line malfunction)

DETECTION 

CONDITION 



The signal from the combined sensor is not within specification.  

POSSIBLE CAUSE 



Open or short circuit in the CAN2_L wiring harness between combined sensor 
terminal C and DSC/RSC HU/CM terminal M  



Open or short circuit in the CAN2_H wiring harness between combined sensor 
terminal D and DSC/RSC HU/CM terminal P  



Combined sensor malfunction  



DSC/RSC HU/CM malfunction  



Poor connection at connectors (female terminal)  

 

2008 Mazda CX-9 Grand Touring 

2008 BRAKES On-Board Diagnostic (DSC/RSC) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 9:50:13 AM

Page 40 

© 2005 Mitchell Repair Information Company, LLC.