Mazda CX-9 Grand Touring. Manual - part 289

STEP

INSPECTION

ACTION

1

VERIFY FREEZE FRAME DATA HAS 
BEEN RECORDED  



Has FREEZE FRAME DATA been 
recorded?  

Yes Go to the next step.

No

Record FREEZE FRAME DATA on the 

repair order, then go to the next step.

2

VERIFY RELATED REPAIR 
INFORMATION AVAILABILITY  



Verify related Service Bulletins and/or 
on-line repair information availability.  



Is any related Service Bulletins 
available?  

Yes

Perform repair or diagnosis according to the 
available Service Bulletins. 



If the vehicle is not repaired, go to the 
next step.  

No

Go to the next step.

3

INSPECT GENERATOR TERMINAL 
FOR POOR INSTALLATION  



Turn the engine switch off.  



Inspect generator terminal B for 
looseness.  



Are there any malfunction?  

Yes

Connect generator terminal B correctly, then 
go to Step 9.

No

Go to the next step.

4

INSPECT GENERATOR CIRCUIT FOR 
SHORT TO POWER SUPPLY  



Turn the ignition switch to the ON 
position (Engine off).  



Measure the voltage between the 
following terminals: 



Generator terminal RC (wiring 
harness-side) and body ground.  



Generator terminal LI (wiring 
harness-side) and body ground.  



Is the voltage B+?  

Yes

Repair or replace suspected part, then go to 
Step 9.

No

Go to the next step.

5

INSPECT PCM CONNECTOR FOR 
POOR CONNECTION  



Turn the engine switch off.  



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



Are there any malfunction?  

Yes

Repair or replace suspected part, then go to 
Step 9.

No

Go to the next step.

INSPECT GENERATOR CIRCUIT FOR 
OPEN CIRCUIT  



Inspect for continuity between generator 

Yes Go to the next step.

 

2008 Mazda CX-9 Grand Touring 

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:08:40 AM

Page 289 

© 2005 Mitchell Repair Information Company, LLC. 

DTC P0642 [MZI-3.7] 

DTC P0642 (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES 

6

terminal RC (wiring harness-side) and 
PCM terminal 2S (wiring harness-side).  



Is there continuity?  

No

Repair or replace suspected part, then go to 

Step 9.

7

INSPECT BATTERY POSITIVE 
TERMINAL FOR POOR INSTALLATION
 



Turn the engine switch off.  



Inspect the battery positive terminal for 
looseness.  



Is there any malfunction?  

Yes

Connect the battery positive terminal 
correctly, then go to Step 9.

No

Go to the next step.

8

INSPECT GENERATOR CIRCUIT FOR 
OPEN CIRCUIT  



Inspect the continuity between generator 
terminal B (wiring harness-side) and 
battery positive terminal (wiring 
harness-side)  



Is there continuity?  

Yes Go to the next step.

No

Repair or replace suspected part, then go to 

the next step.

9

VERIFY TROUBLESHOOTING OF DTC 
P0626 HAS BEEN COMPLETED  



Verify that all disconnected connectors 
reconnected.  



Clear the DTC from the PCM memory 
using the M-MDS.  



Perform the KOEO or KOER self-test 
using the M-MDS. (See KOEO/KOER 
SELF TEST [MZI-3.7].)  



Is the PENDING CODE for the DTC 
present?  

Yes

Replace the PCM, then go to the next step. 
(See PCM REMOVAL/INSTALLATION 
[MZI-3.7] .)

No

Go to the next step.

10

VERIFY AFTER REPAIR PROCEDURE 



Perform the "AFTER REPAIR 
PROCEDURE". (See AFTER REPAIR 
PROCEDURE [MZI-3.7].)  



Are any DTCs present?  

Yes

Go to the applicable DTC inspection. (See 
DTC TABLE [MZI-3.7].)

No

Troubleshooting completed.

DTC P0642

Sensor reference voltage circuit low

DETECTION 

CONDITION 



Indicates the reference voltage circuit is lower than reference voltage 
minimum.  

 

2008 Mazda CX-9 Grand Touring 

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:08:40 AM

Page 290 

© 2005 Mitchell Repair Information Company, LLC. 

DIAGNOSTIC PROCEDURE 

DTC P0642 (MZI-3.7) DIAGNOSTIC PROCEDURE 

POSSIBLE CAUSE 



Short to ground between fuel tank pressure sensor terminal C and PCM 
terminal 1U  



Fuel tank pressure sensor malfunction  



Connector or terminal malfunction  

STEP

INSPECTION

ACTION

VERIFY FREEZE FRAME DATA 

Yes Go to the next step.

 

2008 Mazda CX-9 Grand Touring 

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:08:40 AM

Page 291 

© 2005 Mitchell Repair Information Company, LLC. 

1

HAS BEEN RECORDED  



Has FREEZE FRAME DATA been 
recorded?  

No

Record FREEZE FRAME DATA on the repair 

order, then go to the next step.

2

VERIFY RELATED REPAIR 
INFORMATION AVAILABILITY  



Verify related Service Bulletins 
and/or on-line repair information 
availability.  



Is any related Service Bulletins 
available?  

Yes

Perform repair or diagnosis according to the 
available Service Bulletins. 



If the vehicle is not repaired, go to the next 
step.  

No

Go to the next step.

3

INSPECT FUEL TANK PRESSURE 
SENSOR CONNECTOR FOR POOR 
CONNECTION  



Turn the ignition switch off.  



Disconnect the fuel tank pressure 
sensor connector.  



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



Are there any malfunction?  

Yes Repair or replace suspected part, then go to Step 7.

No

Go to the next step.

4

INSPECT PCM CONNECTOR FOR 
POOR CONNECTION  



Turn the ignition switch off.  



Disconnect the PCM connector.  



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



Are there any malfunction?  

Yes Repair or replace suspected part, then go to Step 7.

No

Go to the next step.

5

INSPECT FUEL TANK PRESSURE 
SENSOR CIRCUIT FOR SHORT TO 
GROUND  



Turn the ignition switch off.  



Inspect the continuity between fuel 
tank pressure sensor terminal C 
(wiring harness-side) and body 
ground.  



Is there continuity?  

Yes Repair or replace suspected part, then go to Step 7.

No

Go to the next step.

INSPECT FUEL TANK PRESSURE 
SENSOR  

 

2008 Mazda CX-9 Grand Touring 

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:08:40 AM

Page 292 

© 2005 Mitchell Repair Information Company, LLC.