Mazda 6. Manual - part 155

F–142

ON-BOARD DIAGNOSTIC 

DTC P0500

A6E397001087W01

Diagnostic procedure

DTC P0500

Vehicle speed sensor (VSS) circuit malfunction (MTX vehicles without ABS)

DETECTION 

CONDITION

• Vehicle speed signal does not input after following conditions are met:

— Gear is in other than neutral position
— Load is above 40%
— Engine speed is 2,000 rpm or above

Diagnostic support note:

• This is a continuous monitor (CCM).

• MIL illuminates if PCM detects the above malfunction conditions in two consecutive drive cycles or in one 

drive cycle while the DTC for the same malfunction has been stored in the PCM.

• PENDING CODE is available if PCM detects the above malfunction condition during first drive cycle.

• FREEZE FRAME DATA is available.

• DTC is stored in PCM memory.

POSSIBLE 

CAUSE

• VSS malfunction

• ABS/TCS/DCS malfunction

• Connector or terminal malfunction

• Open circuit between PCM terminal 2I and VSS terminal A

• Open circuit between PCM terminal 2L and VSS terminal B

• Short to ground between PCM terminal 2I and VSS terminal A

• Short to ground between PCM terminal 2L and VSS terminal B

• Short to power between PCM terminal 2I and VSS terminal A

• Short to power between PCM terminal 2L and VSS terminal B

• PCM malfunction

STEP

INSPECTION

ACTION

1

VERIFY FREEZE FRAME DATA HAS BEEN 
RECORDED

• Has FREEZE FRAME PID DATA been 

recorded?

Yes Go to next step.

No

Record FREEZE FRAME PID DATA on repair order, then 
go to next step.

2

VERIFY RELATED SERVICE INFORMATION 
AVAILABILITY

• Check for related Service Information 

availability.

• Is any related Service Information available?

Yes Perform repair or diagnosis according to available Service 

Information.

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

No

Go to next step.

ON-BOARD DIAGNOSTIC 

F–143

F

3

VERIFY CURRENT INPUT SIGNAL STATUS-IS 
CONCERN INTERMITTENT OR CONSTANT

• Connect WDS or equivalent to DLC-2.

• Start engine.

• Access VSS PID using WDS or equivalent.

— Vehicle speed 20 km/h {12.4 mph}: 20km/

h {12.4 mph}

— Vehicle speed 40 km/h {24.8 mph}: 40km/

h {24.8 mph}

• Are PID readings within specification?

Yes Go to intermittent concern troubleshooting procedure.

(See 

F–227 INTERMITTENT CONCERN 

TROUBLESHOOTING

.)

No

Go to next step.

4

INSPECT POOR CONNECTION OF VSS 
CONNECTOR

• Verify that the VSS connector is connected 

securely.

• Is connector okay?

Yes Go to next step.

No

Reconnect the connector, then go to Step 11.

5

INSPECT VSS

• Perform VSS inspection.

(See 

J–5 VEHICLE SPEEDOMETER 

SENSOR INSPECTION

)

• Is VSS okay?

Yes Go to next step.

No

Replace VSS, then go to Step 11.

6

INSPECT VSS CIRCUIT FOR SHORT TO 
POWER

• Turn ignition key OFF

• Disconnect VSS connector.

• Turn ignition key ON (Engine OFF)

• Measure voltage following terminals:

— VSS terminal A
— VSS terminal B

• Is any voltage reading?

Yes Repair or replace suspected harness, then go to Step 11.

No

Go to next step.

7

INSPECT VSS CIRCUIT FOR SHORT TO 
GROUND

• Inspect continuity between following terminal 

and body ground:
— VSS terminal A
— VSS terminal B

• Is there any continuity?

Yes Repair or replace suspected harness, then go to Step 11.

No

Go to next step.

8

INSPECT VSS CIRCUITS FOR SHORTS

• Inspect continuity between VSS connector 

terminals A and B.

• Is there any continuity?

Yes Repair or replace suspected harness, then go to Step 11.

No

Go to next step.

9

INSPECT POOR CONNECTION OF PCM 
CONNECTOR

• Disconnect PCM connector.

• Inspect for poor connection (damaged, pulled-

out terminals, corrosion, etc.).

• Is there any malfunction?

Yes Repair terminal, then go to Step 11.

No

Go to next step.

10

INSPECT VSS CIRCUIT FOR OPEN CIRCUIT

• Inspect continuity between following circuits:

— VSS terminal A and PCM terminal 2I
— VSS terminal B and PCM terminal 2L

• Is there continuity?

Yes Inspect VSS pulse wheel for damage. Replace VSS pulse 

wheel and go to next step.

No

Repair or replace suspected harness, then go to next step.

STEP

INSPECTION

ACTION

F–144

ON-BOARD DIAGNOSTIC 

End Of Sie

DTC P0505

A6E397001087W02

Diagnostic procedure

11

VERIFY TROUBLESHOOTING OF DTC P0500 
COMPLETED

• Make sure to reconnect all disconnected 

connectors.

• Turn ignition key to ON (Engine OFF).

• Clear DTC from PCM memory using WDS or 

equivalent.

• Warm up engine.

• Access RPM and LOAD PID using WDS or 

equivalent.

• Drive vehicle under following conditions for 

18s.
— Engine speed: 2,000 rpm or above
— Gear: Gear is in other than NEUTRAL
— Load: 40% or above

• Is PENDING CODE the same as DTC 

present?

Yes Replace PCM, then go to next step.

(See 

F–43 PCM REMOVAL/INSTALLATION

.)

No

Go to next step.

12

VERIFY AFTER REPAIR PROCEDURE

• Perform “After Repair Procedure”.

(See 

F–66 AFTER REPAIR PROCEDURE

.)

• Is there any DTC present?

Yes Go to applicable DTC troubleshooting.

(See 

F–67 DTC TABLE

.)

No

Troubleshooting completed.

STEP

INSPECTION

ACTION

DTC P0505

IAC valve circuit malfunction

DETECTION 

CONDITION

• PCM cannot control idle speed toward target idle speed while KOER self test.

POSSIBLE 

CAUSE

• IAC valve circuit malfunction

• Air cleaner element clogged

• Air intake passage clogged

• A/C relay control circuit malfunction

• Generator control circuit malfunction

• Low engine compression (Over capacity of blow-by gas)

• PCM malfunction

STEP

INSPECTION

ACTION

1

VERIFY RELATED SERVICE INFORMATION 
AVAILABILITY

• Check for related Service Information 

availability.

• Is any related Service Information available?

Yes Perform repair or diagnosis according to available Service 

Information.

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

No

Go to next step.

2

VERIFY RELATED PENDING OR STORED 
DTCS

• Turn ignition switch to OFF, then ON. (Engine 

OFF)

• verify pending code or stored DTCs using 

WDS or equivalent.

• Does DTC P0511,P2502, P2503 or P2504 

present?

Yes Perform applicable DTC troubleshooting.

(See 

F–67 DTC TABLE

.)

No

Go to next step.

3

INSPECT IAC VALVE MALFUNCTION

• Start engine.

• Disconnect IAC valve connector.

• Is engine speed decreased?.

Yes Go to next step.

No

Repair IAC valve, then go to Step 9.

4

INSPECT A/C MAGNETIC CLUTCH 
OPERATION

Note

• The following test should be performed for 

A/C.go to next step for vehicles without A/C

• Turn blower motor switch to off.

• Is magnetic clutch still on?

Yes Go to “A/C ALWAYS ON / A/C COMPRESSOR RUNS 

CONTINUOUSLY.” of ENGINE SYMPTOM 
TROUBLESHOOTING then go to step 9.
(See 

F–181 ENGINE SYMPTOM TROUBLESHOOTING

.)

No

Go to next step.

ON-BOARD DIAGNOSTIC 

F–145

F

End Of Sie

DTC P0506

A6E397001087W03

Diagnostic procedure

5

INSPECT GENERATOR CONTROL CIRCUIT 
MALFUNCTION

• Apply electrical load.

• Is engine speed increased?

Yes Go to next step.

No

Repair short to power circuit in generator control circuit, 
then go to Step 9.

6

INSPECT AIR CLEANER ELEMENT

• remove air cleaner element with engine 

running.

• Is engine speed increased?

Yes Clean or replace air cleaner element, then go to Step 9.

No

Go to next step.

7

INSPECT THROTTLE BODY PASSAGE

• Is throttle body clogged?

Yes Clean or replace throttle body passage, then go to Step 9.

No

Go to next step.

8

INSPECT ENGINE COMPRESSION

• Inspect engine compression.

(See 

B–9 COMPRESSION INSPECTION

.)

• Is engine compression okay?

Yes Go to next step.

No

Overhaul engine, then go to next step.

9

VERIFY TROUBLESHOOTING OF DTC P0505 
COMPLETED

• Make sure to reconnect all disconnected 

connectors.

• Clear DTC using WDS or equivalent.

• Perform KOER self-test.

(See 

F–66 KOEO/KOER SELF-TEST

.)

• Is same DTC present?

Yes Replace PCM, then go to next step.

(See 

F–43 PCM REMOVAL/INSTALLATION

.)

No

Go to next step.

10

VERIFY AFTER REPAIR PROCEDURE

• Perform “After Repair Procedure”.

(See 

F–66 AFTER REPAIR PROCEDURE

.)

• Is there any DTC present?

Yes Go to applicable DTC troubleshooting.

(See 

F–67 DTC TABLE

.)

No

Troubleshooting completed.

STEP

INSPECTION

ACTION

DTC P0506

Idle control system RPM lower than expected

DETECTION 

CONDITION

• Actual idle speed is lower than expected by 100 rpm for 14 s, when brake pedal is depressed (brake 

switch is on) and steering wheel is held straight ahead (power steering pressure switch is off).

Note

• If atmospheric pressure is less than 72.3 kPa {542 mmHg, 21.3 inHg} or intake air temperature is 

below -10 

°C {14 °F}, PCM cancels diagnosis of P0506.

Diagnostic support note

• This is a continuous monitor (CCM).

• MIL illuminates if PCM detects the above malfunction conditions in two consecutive drive cycles or in one 

drive cycle while the DTC for the same malfunction has been stored in the PCM.

• PENDING CODE is available if PCM detects the above malfunction condition during first drive cycle.

• FREEZE FRAME DATA is available.

• DTC is stored in PCM memory.

POSSIBLE 

CAUSE

• IAC valve malfunction

• Air cleaner element clogged

• Air intake passage clogged

• A/C relay control circuit malfunction

• Generator malfunction

• Purge solenoid valve malfunction

• Low engine compression (Over capacity of blow-by gas)

• PCM malfunction

STEP

INSPECTION

ACTION

1

VERIFY FREEZE FRAME DATA HAS BEEN 
RECORDED

• Has FREEZE FRAME DATA been recorded?

Yes Go to next step.

No

Record FREEZE FRAME DATA on repair order, then go to 
next step.

2

VERIFY RELATED SERVICE INFORMATION 
AVAILABILITY

• Check for related Service Information 

availability.

• Is any related Service Information available?

Yes Perform repair or diagnosis according to available Service 

Information.

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

No

Go to next step.