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DTC P0504: Brake Switch Circuit 1 - 2 Correlation: Troubleshooting

TROUBLESHOOTING CHART

Step Action Value(s) Yes No
1 Did you perform the Diagnostic System Check? - Go to Step 2 Go to On-Board Diagnostic (OBD II) System Check
2
  1. With the scan tool, observe the brake lamp switch parameter and the brake pedal switch parameter.
  2. Press and release the brake pedal.

Does the brake lamp switch parameter and brake pedal switch parameter display change closely with each other?		 - Go to Diagnostic Aids Go to Step 3
3
  1. With the scan tool, observe the brake pedal switch parameter.
  2. Press and release the brake pedal.

Does the brake pedal switch parameter display change with the brake pedal position?		 - Go to Step 6 Go to Step 4
4
  1. Turn the ignition OFF.
  2. Disconnect the brake lamp switch.
  3. Turn the ignition ON, with the engine OFF.

Does the brake pedal switch parameter display released?		 - Go to Step 5 Go to Step 12
5
  1. Turn the ignition OFF.
  2. Connect a 10 A fused jumper between the ignition positive voltage circuit of the brake lamp switch and the brake pedal switch signal circuit of the brake lamp switch.
  3. Turn the ignition ON, with the engine OFF.

Does the brake pedal switch parameter display applied?		 - Go to Step 15 Go to Step 8
6
  1. Turn the ignition OFF.
  2. Disconnect the brake lamp switch.
  3. Turn the ignition ON, with the engine OFF.
  4. With the scan tool, observe the brake lamp switch parameter.

Does the brake lamp switch parameter display released?		 - Go to Step 7 Go to Step 10
7
  1. Turn the ignition OFF.
  2. Connect a 20 A fused jumper between the B (+) voltage circuit of the brake lamp switch and the brake lamp switch signal circuit.
  3. Turn the ignition ON, with the engine OFF.

Does the brake lamp switch parameter display applied?		 - Go to Step 15 Go to Step 11
8 Test the ignition positive voltage circuit of the brake lamp switch for an open or short to ground.
Did you find and correct the condition?		 - Go to Step 18 Go to Step 9
9 Test for an open or short to ground in the brake pedal signal circuit of the brake lamp switch.
Did you find and correct the condition?		 - Go to Step 18 Go to Step 14
10 Test the brake lamp switch signal circuit for a short to voltage.
Did you find and correct the condition?		 - Go to Step 18 Go to Step 14
11 Test the B (+) voltage circuit of the brake lamp switch for an open or short to ground.
Did you find and correct the condition?		 - Go to Step 18 Go to Step 13
12 Test the brake pedal switch signal circuit of the brake lamp switch for a short to voltage.
Did you find and correct the condition?		 - Go to Step 18 Go to Step 16
13 Test the brake lamp switch signal circuit for an open or short to ground.
Did you find and correct the condition?		 - Go to Step 18 Go to Step 14
14 Inspect for poor connections at the harness connector of the Engine Control Module (ECM).
Did you find and correct the condition?		 - Go to Step 18 Go to Step 16
15 Inspect for poor connections at the harness connector of the brake lamp switch.
Did you find and correct the condition?		 - Go to Step 18 Go to Step 17
16 Replace the ECM.
Did you complete the replacement?		 - Go to Step 18 -
17 Replace the brake lamp switch.
Did you complete the replacement?		 - Go to Step 18 -
18
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Setting the DTC.

Does the DTC reset?		 - Go to Step 2 System OK
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