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Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. 3:  Tests the circuit for a change in states.
  2. 5:  Tests for proper operation of the circuit by bypassing the stop lamp switch. If the fuse in the jumper opens when you perform this test, the signal circuit of the stop lamp switch is shorted to ground.
DTC C1291

Step Action Yes No
Schematic Reference: ABS Schematics 
Connector End View Reference: ABS Connector End Views  or Lighting Systems Connector End Views in Lighting Systems
1 Did you perform the Diagnostic System Check - Vehicle? Go to Step 2  Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2 Press the brake pedal.
Do the brake lamps turn ON?		 Go to Step 3  Go to Step 7 
3 
  1. Press the brake pedal.
  2. With a scan tool, observe the Brake Switch Status parameter in the ABS data list.
Does the Brake Switch Status parameter change state?		 Go to Diagnostic Aids Go to Step 4 
4
  1. Turn OFF the ignition.
  2. Inspect the stop lamp switch and adjust and/or calibrate if needed. Refer to Stop Lamp Switch Adjustment in Lighting Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 5 
5 
  1. Turn OFF the ignition.
  2. Disconnect the stop lamp switch connector.
  3. Connect a 3-amp fused jumper wire between the battery positive voltage circuit of the stop lamp switch and the signal circuit of the stop lamp switch.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, observe the Brake Switch Status parameter.
Does the scan tool display Applied?		 Go to Step 11  Go to Step 6 
6 Test the signal circuit of the stop lamp switch for an open between the splice pack of the stop lamp signal circuit and the electronic brake control module (EBCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 10 
7 Test the battery positive voltage circuit of the stop lamp switch for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 8 
8 Test the signal circuit of the stop lamp switch for an open between the stop lamp switch and the splice of the stop lamp signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 9 
9 Test the signal circuit of the stop lamp switch for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 10 
10 Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 12 
11 Inspect for poor connections at the harness connector of the stop lamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 14  Go to Step 13 
12 Replace the EBCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
Did you complete the repair?		 Go to Step 14  -
13 Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement in Lighting Systems.
Did you complete the repair?		 Go to Step 14  -
14
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?		 Go to Step 2  System OK
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