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Diagnostic Aids

Step Action Yes No
Schematic Reference: Exterior Lights Schematics  and Cruise Control Schematics (w/o Throttle Actuator Control) or Cruise Control Schematics (w/ Throttle Actuator Control)
Connector End View Reference: Lighting Systems Connector End Views 
1 Did you perform the Diagnostic System Check - Vehicle? Go to Step 2  Go to Diagnostic System Check - Vehicle .
2
  1. With the scan tool, observe the brake lamp switch and 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 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 OFF the ignition.
  2. Disconnect the brake lamp switch
  3. Turn ON the ignition, with the engine OFF.
Does the brake pedal; switch parameter display released?		 Go to Step 5  Go to Step 12 
5
  1. Turn OFF the ignition.
  2. Connect a 10-amp 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 ON the ignition, with the engine OFF.
Does the brake pedal switch parameter display applied?		 Go to Step 15  Go to Step 8 
6
  1. Turn OFF the ignition.
  2. Disconnect the brake lamp switch.
  3. Turn ON the ignition, 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 OFF the ignition.
  2. Connect a 20-amp fused jumper between the battery positive voltage circuit of the brake lamp switch and the brake lamp signal circuit
  3. Turn ON the ignition, 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 battery 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 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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