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2008 - MX-5 - Body and Accessories

NO.1 ONE OR MORE ON-BOARD DIAGNOSTIC FUNCTIONS INOPERATIVE [KEYLESS ENTRY SYSTEM]



1

One or more on-board diagnostic functions inoperative

DESCRIPTION

  • Malfunction in trunk lid opener system, horn system, hazard warning light system, or door lock linkage system

POSSIBLE CAUSE

  • Malfunction in trunk lid opener system

    • Trunk lid opener relay circuit malfunction

    • Keyless control module malfunction

  • Malfunction in horn system

    • Horn circuit malfunction

    • Keyless control module malfunction

    • Malfunction in wiring harness between keyless control module and horn relay

  • Malfunction in hazard warning light system

    • Hazard warning light circuit

    • Keyless control module malfunction

    • Malfunction in wiring harness between keyless control module and hazard warning lights

    • Malfunction in wiring harness between keyless control module and flasher control module

  • Malfunction in door lock linkage

  • Malfunction in keyless control module door lock/unlock signal circuit

    • Keyless control module malfunction


Diagnostic procedure



STEP

INSPECTION

ACTION

1

INSPECT HORN AND HAZARD WARNING LIGHT OPERATION DURING ON-BOARD DIAGNOSIS

  • Do all of the following items work during on-board diagnostic function operation?

    • Hazard warning lights flash.

    • Horns sounds intermittently.

    • Trunk lid opens.

Yes

Go to step 11.

No

Go to the next step.

2

INSPECT HAZARD WARNING LIGHT OPERATION DURING ON-BOARD DIAGNOSIS

  • Do the hazard warning lights flash during on-board diagnostic function operation?

Yes

Go to step 5.

No

Go to the next step.

3

INSPECT HAZARD WARNING LIGHT CIRCUIT

  • Do the hazard warning lights flash when hazard warning switch is on?

Yes

Go to the next step.

No

Inspect the hazard warning light circuit.

*4

INSPECT IF MALFUNCTION IS IN WIRING HARNESS (BETWEEN KEYLESS CONTROL MODULE AND FLASHER CONTROL MODULE) OR KEYLESS CONTROL MODULE

  • Measure the voltage at keyless control module connector terminal 3N during on-board diagnostic function operation.

    • When hazard warning lights flashed: Alternates between B+ and below 1.0 V

  • Is the voltage as above?

Yes

Reinspect the malfunction symptoms, then repeat from step 1 if malfunction recurs.

No

  • Inspect the wiring harness between the keyless control module and flasher control module.

    • If the wiring harness is normal, replace the keyless control module and reprogram the transmitter ID code, then go to step 14.

    • If the wiring harness is malfunctioning, repair the wiring harness, then go to step 14.

5

INSPECT HORN OPERATION DURING ON-BOARD DIAGNOSIS

  • Dose horn sound intermittently during on-board diagnostic function operation?

Yes

Go to step 8.

No

Go to the next step.

6

INSPECT HORN CIRCUIT

  • Does horn sound when the horn switch on the vehicle is pressed?

Yes

Go to the next step.

No

Inspect the horn circuit.

*7

INSPECT IF MALFUNCTION IS IN WIRING HARNESS (NO CONTINUITY BETWEEN KEYLESS CONTROL MODULE AND HORN RELAY) OR KEYLESS CONTROL MODULE

  • Turn the ignition switch to the LOCK position.

  • Disconnect the keyless control module connector and horn relay connector.

  • Is there continuity between keyless control module connector terminal 4U and horn relay connector?

Yes

Replace the keyless control module and reprogram the keyless control module ID code, then go to step 14.

No

Repair the wiring harness between the keyless control module and horn relay, then go to step 14.

8

CHECK TRUNK LID OPERATION DURING ON-BOARD DIAGNOSIS

  • Does the trunk lid open during on-board diagnostic function operation?

Yes

Go to step 11.

No

Go to the next step.

9

INSPECT TRUNK LID OPENER SYSTEM

  • Does the trunk lid open by the trunk lid opener switch?

Yes

Go to the next step.

No

Inspect the trunk lid opener system.

*10

INSPECT IF MALFUNCTION IS IN TRUNK LID OPENER RELAY CIRCUIT OR KEYLESS CONTROL MODULE

  • Disconnect the keyless control module connector.

  • Measure the voltage at keyless control module connector terminal 4P.

  • Is the voltage approx. 12 V?

Yes

Replace the keyless control module and the reprogram transmitter ID code, then go to step 14.

No

Inspect the trunk lid opener relay circuit.

11

VERIFY THAT ALL DOORS LOCK AND UNLOCK DURING ON-BOARD DIAGNOSIS

  • Do all doors unlock and lock during on-board diagnostic function operation?

Yes

Reinspect the malfunction symptoms, then repeat from step 1 if the malfunction recurs.

No

Go to the next step.

12

INSPECT DOOR LOCK LINKAGE

  • Operate the door lock knob and verify the door locks and unlocks manually.

  • Does every door lock system work?

Yes

Go to the next step.

No

Inspect the door lock linkage.

*13

INSPECT IF MALFUNCTION IS IN DOOR LOCK ACTUATOR, KEYLESS CONTROL MODULE GROUND CIRCUIT OR ELSEWHERE

  • Measure the voltage at keyless control module connector terminals 1C and 1A.

    • All doors locked: Cycles 1.0 V or less B+1.0 V or less (terminal 1C)

    • All doors unlocked: Cycles B+1.0 V or lessB+ (terminal 1A)

  • Is the voltage as above?

Yes

Reinspect the malfunction symptoms, then repeat from step 1 if the malfunction recurs.

No

  • Inspect the keyless control module the connector.

  • Inspect the wiring harness between the keyless control module and door lock actuator.

    • If the above parts are normal, go to the next step.

    • If any of above parts are malfunctioning, repair the malfunctioning part.

14

REINSPECT MALFUNCTION SYMPTOM AFTER REPAIR

  • Does the keyless entry system operate properly?

Yes

Troubleshooting completed.

Explain repairs to customer.

No

Reinspect the malfunction symptoms, then repeat from step 1 if malfunction recurs.




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