Mazda CX-9 Grand Touring. Manual — part 291

DIAGNOSTIC PROCEDURE

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 297

© 2005 Mitchell Repair Information Company, LLC.

DTC P0645 (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.

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 THAT THE ACCS PID IS
OFF



Turn ignition key to ON (Engine
running).



A/C switch and defroster switch off.



Access the ACCS PID uesing M-
MDS.



Is the PID state off?

Yes Go to the next step.

No

ACCS input to PCM is requesting A/C. Inspect

A/C system operation, then go to Step 12.
(See DIAGNOSTIC TROUBLE CODE

NUMBER INSPECTION .)

(See TROUBLESHOOTING INDEX .)

4

INSPECT A/C RELAY CONNECTOR
FOR POOR CONNECTOR



Turn the ignition switch off.



Disconnect the A/C relay connector.



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



Are there any malfunction?

Yes

Repair or replace suspected part, then go to Step
12.

No

Go to the next step.

5

INSPECT A/C RELAY POWER
SUPPLY CIRCUIT FOR OPEN
CIRCUIT



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



Measure voltage between A/C relay
terminal A (wiring harness-side) and
body ground.



Is voltage B+?

Yes Go to the next step.

No

Repair or replace suspected part, then go to Step

12.

INSPECT A/C RELAY CONTROL

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 298

© 2005 Mitchell Repair Information Company, LLC.

6

CIRCUIT FOR SHORT TO POWER
SUPPLY



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



Remove the A/C relay.



Measure voltage between A/C relay
terminal E (wiring harness-side) and
body ground.



Is voltage B+?

Yes

Repair or replace suspected part, then go to Step
12.

No

Go to the next step.

7

INSPECT A/C RELAY CONTROL
CIRCUIT FOR SHORT TO GROUND



Install the A/C relay.



Turn the ignition switch off.



Inspect continuity between A/C relay
terminal E (wiring harness-side) and
body ground.



Is there continuity?

Yes

Repair or replace suspected part, then go to Step
12.

No

Go to the next step.

8

INSPECT PCM CONNECTOR FOR
POOR CONNECTION



Turn ignition switch to off.



Disconnect the PCM connector.



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



Is there any malfunction?

Yes

Repair or replace suspected part, then go to Step
12.

No

Go to the next step.

9

INSPECT A/C RELAY CONTROL
CIRCUIT FOR OPEN CIRCUIT



Turn the ignition switch off.



Inspect continuity between A/C relay
terminal E (wiring harness-side) and
PCM terminal 1N (wiring harness-
side).



Is there continuity?

Yes Go to the next step.

No

Repair or replace suspected part, then go to Step

12.

10

INSPECT A/C RELAY



Inspect A/C relay. (See RELAY
INSPECTION .)



Is A/C relay normal?

Yes Go to the next step.

No

Replace the A/C relay. Start the engine. Turn on

the A/C switch. Wait for 15 s. Turn off the A/C

switch, then go to Step 12.

INSPECT FOR CORRECT PCM
OPERATION

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 299

© 2005 Mitchell Repair Information Company, LLC.

DTC P0685 [MZI-3.7]

DTC P0685 (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES

11



Disconnect all the PCM connectors.



Visually inspect for:



Pushed out pins



Corrosion



Connect all the PCM connectors and
verify that they seat correctly.



Retrieve DTCs using the M-MDS.



Is the PENDING CODE for this
DTC present?

Yes Go to the next step.

No

The system is correctly. Go to the next step.

12

VERIFY TROUBLESHOOTING OF
DTC P0645 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.

13

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 P0685

ECM/PCM power relay control circuit/open

DETECTION

CONDITION



This DTC sets when the ignition switch position run circuit indicates the key is in the
off, ACC, or LOCK position, and the amount of time the PCM remains powered
through the PCM power relay exceeds a predetermined amount of time.

POSSIBLE

CAUSE



Short to ground circuit between main relay No.1 terminal A and PCM terminal 1BM



Main relay No.1 malfunction



PCM 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 300

© 2005 Mitchell Repair Information Company, LLC.