Mazda CX-9 Grand Touring. Manual - part 541

DTC B2939 [POWER LIFTGATE (PLG) SYSTEM] 

DTC B2939 - DETECTION CONDITION POSSIBLE CAUSE CHART 

1



Disconnect the PLG control module 
connector.  



Disconnect the PLG drive unit 
connector.  



Inspect the wiring harness between 
PLG control module terminals 1E and 
1F, and PLG drive unit terminals A and 
B for an open circuit.  



Is the wiring harness normal?  

Yes

(See POWER LIFTGATE (PLG) DRIVE 
UNIT REMOVAL/INSTALLATION .) 
Go to the next step.

No

Repair or replace the wiring harness. 

Go to the next step.

2

VERIFY CORRECTION COMPLETED 



Reconnect the disconnected connector. 



Clear the DTC.  



Operate the PLG system.  



Is DTC B2937 stored?  

Yes

Replace the PLG control module. 
(See POWER LIFTGATE (PLG) 
CONTROL MODULE 
REMOVAL/INSTALLATION .)

No

DTC troubleshooting completed.

DTC B2939

Clutch circuit malfunction

DETECTION 

CONDITION 

The current flowing to the PLG motor is normal (1 A or more), however, the output 
signal of rotation sensor A continues to not change while the PLG is operating.

POSSIBLE CAUSE 



Open circuit in wiring harness between PLG control module terminal 21 and PLG 
drive unit terminal M  



Open circuit in wiring harness between PLG control module terminal 2G and PLG 
drive unit terminal N  



Clutch malfunction  



PLG control module malfunction  

 

2008 Mazda CX-9 Grand Touring 

2008 BODY & ACCESSORIES On-Board Diagnostic (Power Liftgate (PLG) System) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:46:08 AM

Page 40 

© 2005 Mitchell Repair Information Company, LLC. 

DIAGNOSTIC PROCEDURE 

DTC B2939 - DIAGNOSTIC PROCEDURE 

STEP

INSPECTION

ACTION

INSPECT WIRING HARNESS 
BETWEEN PLG CONTROL MODULE 
AND PLG DRIVE UNIT  

 

2008 Mazda CX-9 Grand Touring 

2008 BODY & ACCESSORIES On-Board Diagnostic (Power Liftgate (PLG) System) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:46:08 AM

Page 41 

© 2005 Mitchell Repair Information Company, LLC. 

1



Disconnect the PLG control module 
connector.  



Disconnect the PLG drive unit 
connector.  



Inspect the wiring harness between 
PLG control module terminals 21 and 
2G, and PLG drive unit terminals M 
and N for an open circuit.  



Is the wiring harness normal?  

Yes

Replace the PLG drive unit. 
(See POWER LIFTGATE (PLG) DRIVE 
UNIT REMOVAL/INSTALLATION .) 
Go to the next step.

No

Repair or replace the wiring harness. 

Go to the next step.

2

VERIFY CORRECTION COMPLETED 



Reconnect the disconnected connector. 



Clear the DTC.  



Operate the PLG system.  



Is DTC B2939 stored?  

Yes

Replace the PLG control module. 
(See POWER LIFTGATE (PLG) 
CONTROL MODULE 
REMOVAL/INSTALLATION .)

No

DTC troubleshooting completed.

 

2008 Mazda CX-9 Grand Touring 

2008 BODY & ACCESSORIES On-Board Diagnostic (Power Liftgate (PLG) System) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:46:08 AM

Page 42 

© 2005 Mitchell Repair Information Company, LLC. 

2008 STEERING

Power Steering - Mazda CX-9 

STEERING LOCATION INDEX 

Fig. 1: Identifying Steering Location Index 
Courtesy of MAZDA MOTORS CORP. 

AIR BLEEDING 

1. Inspect the fluid level. (See POWER STEERING FLUID INSPECTION.)  

2. Jack up the front of the vehicle and support it on safety stands.  

3. Turn the steering wheel fully to the left and right several times with the engine not running.  

4. Reinspect the fluid level. 



If it has dropped, add fluid.  

5. Repeat Steps 3 and 4 until the fluid level stabilizes.  

6. Lower the vehicle.  

7. Start the engine and let it idle.  

8. Turn the steering wheel fully to the left and right several times.  

9. Verify that the fluid is not foamy and that the fluid level has not dropped. 



If the fluid level has dropped, add fluid as necessary and repeat Steps 8 and 9.  

POWER STEERING FLUID INSPECTION

CAUTION:



Do not turn the steering wheel during the fluid level inspection, 
otherwise the fluid level changes and cannot be inspected correctly.  

 

2008 Mazda CX-9 Grand Touring 

2008 STEERING Power Steering - Mazda CX-9

  

 

2008 Mazda CX-9 Grand Touring 

2008 STEERING Power Steering - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:20:34 AM

Page 1 

© 2005 Mitchell Repair Information Company, LLC. 

Microsoft 

 

Sunday, November 15, 2009 10:20:39 AM

Page 1 

© 2005 Mitchell Repair Information Company, LLC.