GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2006 🢒 GMC C Sierra - 2WD 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C0161

Circuit Description

The brake switch informs the electronic brake control module (EBCM) when the brake is depressed. The brake switch is normally closed, supplying 12 volts to the EBCM when the brake is released. When the brake pedal is pressed, voltage on the torque converter clutch (TCC) brake switch signal circuit is 0 volts.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0161 Antilock Brake System (ABS)/Traction Control System (TCS) Brake Switch

Conditions for Running the DTC

Any of the following conditions may cause the diagnostic trouble code (DTC) to run:

    • The vehicle accelerates from 0 km/h (0 mph) to a speed greater than 56 km/h (35 mph).
    • The vehicle experiences an ABS event involving all hydraulic circuits.

Conditions for Setting the DTC

Any of the following conditions may cause the DTC to set:

    • Voltage on the TCC brake switch signal circuit is always low.
    • Voltage on the TCC brake switch signal circuit is always high.

Action Taken When the DTC Sets

The EBCM stores this information-only DTC for as long as the condition is present.

Conditions for Clearing the DTC

The Conditions for Setting the DTC are no longer present and you use the scan tool Clear DTCs function.

Diagnostic Aids

Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to the following:

    •  Testing for Intermittent Conditions and Poor Connections
    •  Connector Repairs
    •  Testing for Electrical Intermittents
    •  Wiring Repairs

Test Description

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

  1. This step tests for a shorted stop lamp switch.

    2.

  2. This step tests for an open stop lamp switch.

Step

Action

Yes

No

Schematic Reference: Antilock Brake System Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Install a scan tool.
  2. Select the 4WAL 3 Sensor Data Display function.
  3. Observe the Brake Switch Status on the scan tool.

Does the scan tool display OFF?

Go to Step 3

Go to Step 5

3
  1. Apply the brake.
  2. Observe the Brake Switch Status on the scan tool.

Does the scan tool display ON?

Go to Diagnostic Aids

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the stop lamp switch. Refer to Stop Lamp Switch Replacement .
  3. Turn ON the ignition.
  4. Observe the Brake Switch Status on the scan tool.

Does the scan tool display ON?

Go to Step 9

Go to Step 7

5

  1. Turn OFF the ignition.
  2. Disconnect the stop lamp switch. Refer to Stop Lamp Switch Replacement .
  3. Connect a fused jumper wire between the ignition 3 voltage circuit and the torque converter clutch (TCC) brake switch signal circuit at the stop lamp switch harness connector. Refer to Using Fused Jumper Wires .
  4. Turn ON the ignition.
  5. Observe the Brake Switch Status on the scan tool.

Does the scan tool display OFF?

Go to Step 9

Go to Step 6

6

Test the ignition 3 voltage circuit and the TCC brake switch signal circuit for an open or a short to ground. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 8

7

Test the TCC brake switch signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 8

8

Inspect for poor connections at the harness connector of the electronic brake control module (EBCM). Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 10

9

Inspect for poor connections at the harness connector of the stop lamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 11

10

Replace the EBCM. Refer to Control Module References for replacement, setup and programming.

Did you complete the replacement?

Go to Step 12

--

11

Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement .

Did you complete the replacement?

Go to Step 12

--

12
  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