| P0504 | Brake light switch and brake signal correlation |
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DETECTION CONDITION
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• The PCM monitors changes in input signal for brake light switch and brake signal (from instrument cluster). If the PCM does not detect brake light switch signal for 1 sec. after the brake signal inputted from the instrument cluster, the PCM determines that the brake light switch circuit has malfunction.
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POSSIBLE CAUSE
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• Brake light switch malfunction
• Open or short circuit between brake light switch and PCM terminal 317
• Open or short circuit between brake light switch and ground through brake light
• PCM malfunction
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Diagnostic procedure
| STEP | INSPECTION | ACTION | |
|---|---|---|---|
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1
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VERIFY FREEZE FRAME DATA HAS BEEN RECORDED
• Has the FREEZE FRAME DATA been recorded?
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Yes
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Go to the next step.
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No
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Record the FREEZE FRAME DATA on the repair order, then go to the next step.
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2
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VERIFY REPAIR INFORMATION AVAILABILITY
• Verify related service repair information availability.
• Is any related repair information available?
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Yes
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Perform repair or diagnosis according to the available repair information.
If the vehicle is not repaired, go to the next step.
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No
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Go to the next step.
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3
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INSPECT BRAKE LIGHT OPERATION
• Depress the brake pedal several times.
• Does the brake light illuminate according to brake pedal conditions?
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Yes
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Inspect and repair or replace the wiring harness between brake light switch and PCM terminal 317.
Then go to Step 6.
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No
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Go to the next step.
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4
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INSPECT BRAKE LIGHT SWITCH
• Inspect the brake light switch.
• Is the brake light switch normal?
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Yes
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Go to the next step.
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No
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Replace the brake light switch, then go to the Step 6.
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5
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INSPECT BRAKE LIGHT CIRCUIT
• Inspect the wiring harness for following circuits;
• Are there any malfunction detected?
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Yes
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Repair or replace suspected harness, then go to the next step.
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No
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Replace the brake light, then go to the next step.
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6
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VERIFY THAT DTC P0504 TROUBLESHOOTING IS COMPLETED
• Make sure to reconnect all disconnected connectors.
• Clear the DTC from the PCM memory using the M-MDS.
• Start the engine and warm-up to normal operating temperature.
• Depress the brake pedal for several times.
• Retrieve the DTC using the M-MDS.
• Is the PENDING CODE same DTC present?
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Yes
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Replace PCM, then go to the next step.
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No
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Go to the next step.
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7
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VERIFY AFTER REPAIR PROCEDURE
• Perform “After Repair Procedure”.
• Is there any DTC present?
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Yes
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Go to the applicable DTC inspection.
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No
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Troubleshooting completed.
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