Mazda CX-9 Grand Touring. Manual - part 290

 

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Mazda CX-9 Grand Touring. Manual - part 290

 

 

DTC P0643 [MZI-3.7] 

DTC P0643 (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES 

6

Inspect the fuel tank pressure 
sensor. (See FUEL TANK 
PRESSURE SENSOR 
INSPECTION [MZI-3.7]
 .)  

Is there any malfunction?  

Yes

Replace the evaporative hose component, then go 
to the next step. (See FUEL TANK 
REMOVAL/INSTALLATION [MZI-3.7]
 .)

No

Go to the next step.

7

VERIFY TROUBLESHOOTING OF 
DTC P0642 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.

8

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 P0643

Sensor reference voltage circuit high

DETECTION 

CONDITION 

Indicates the reference voltage circuit is higher than reference voltage 
maximum.  

POSSIBLE CAUSE 

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

Fuel tank pressure sensor malfunction  

Connector or terminal malfunction  

 

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 293 

© 2005 Mitchell Repair Information Company, LLC. 

DIAGNOSTIC PROCEDURE 

DTC P0643 (MZI-3.7) DIAGNOSTIC PROCEDURE 

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.

VERIFY RELATED REPAIR 

 

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 294 

© 2005 Mitchell Repair Information Company, LLC. 

2

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 
POWER SUPPLY
  

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

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

Is the voltage B+?  

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

No

Go to the next step.

6

INSPECT FUEL TANK PRESSURE 
SENSOR
  

Inspect the fuel tank pressure sensor. 
(See FUEL TANK PRESSURE 
SENSOR INSPECTION [MZI-
3.7]
 .)  

Is there any malfunction?  

Yes

Replace the evaporative hose component, then go 
to the next step. (See FUEL TANK 
REMOVAL/INSTALLATION [MZI-3.7]
 .)

No

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 295 

© 2005 Mitchell Repair Information Company, LLC. 

DTC P0645 [MZI-3.7] 

DTC P0645 (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES 

7

VERIFY TROUBLESHOOTING OF 
DTC P0643 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.

8

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 P0645

A/C relay control circuit

DETECTION 

CONDITION 

Monitors the A/C relay control circuit output from the PCM. The test fails when the 
PCM grounds the A/C relay control circuit, excessive current draw is detected on the 
A/C relay control circuit; or, with the A/C relay control circuit not grounded by the 
PCM, voltage is not detected on the A/C relay control circuit (the PCM expects to 
detect vehicle power voltage coming through the A/C relay coil to the A/C circuit).  

POSSIBLE 

CAUSE 

A/C relay malfunction  

Connector or terminal malfunction  

Open circuit in wiring between main relay terminal No.1 D and A/C relay terminal A  

Open circuit in wiring between A/C relay terminal E and PCM terminal IN  

Short to ground in wiring between A/C relay terminal E and PCM terminal 1N  

Short to power supply between A/C relay terminal E and PCM terminal 1N  

 

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 296 

© 2005 Mitchell Repair Information Company, LLC. 

 

 

 

 

 

 

 

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