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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 Savana - AWD 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C0161

DTC C0161 W/O JL4

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.

Conditions for Running the DTC

Any of the following conditions may cause the 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 antilock brake system (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 Testing for Intermittent Conditions and Poor Connections , Connector Repairs , Testing for Electrical Intermittents and to Wiring Repairs in Wiring Systems.

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

Connector End View Reference: Antilock Brake System Connector End Views

1

Did you perform the ABS Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - ABS

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 in Lighting Systems.
  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 in Lighting Systems.
  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 in Wiring Systems.
  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 in Wiring Systems.

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 in Wiring Systems.

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 in Wiring Systems.

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 in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 11

10

Important: Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure.

Replace the EBCM. Refer to Electronic Brake Control Module Replacement .

Did you complete the replacement?

Go to Step 12

--

11

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

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

DTC C0161 W/JL4

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.

Conditions for Running the DTC

Any of the following conditions may cause the 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 antilock brake system (ABS) event involving all hydraulic circuits.
    • The EBCM detects that the master cylinder pressure is greater than 1400 kPa (200 psi) and that the vehicle is decelerating.

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.
    • Voltage on the TCC brake switch signal circuit is high for 0.5-4.0 seconds when voltage is expected to be low.

Action Taken When the DTC Sets
    • The EBCM disables the VSES.
    • The traction control system (TCS) operates with engine torque reduction capability only.
    • The stability indicator turns ON.

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 Testing for Intermittent Conditions and Poor Connections , Connector Repairs , Testing for Electrical Intermittents and to Wiring Repairs in Wiring Systems.

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

Connector End View Reference: Lighting Systems Connector End Views in Lighting Systems or Antilock Brake System Connector End Views

1

Did you perform the ABS Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - ABS

2
  1. Select the ABS Data Display function on the scan tool.
  2. 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 in Lighting Systems.
  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 in Lighting Systems.
  3. Connect a fused jumper wire between the ignition 3 voltage circuit and the TCC brake switch signal circuit at the stop lamp switch harness connector. Refer to Using Fused Jumper Wires in Wiring Systems.
  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 torque converter clutch (TCC) brake switch signal circuit for an open or a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

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 in Wiring Systems.

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 in Wiring Systems.

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 in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 11

10

Important: Following EBCM replacement, perform the set-up procedure for the EBCM and perform the Yaw Rate Reference Table Reset Procedure. Use the scan tool to perform the Tire Size Calibration procedure.

Replace the EBCM. Refer to Electronic Brake Control Module Replacement .

Did you complete the replacement?

Go to Step 12

--

11

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

Did you complete the replacement?

Go to Step 12

--

12
  1. Use the scan tool Clear All Class 2 DTCs function to clear all of the DTCs from all modules.
  2. Turn OFF the ignition for 5 seconds.
  3. Turn ON the ignition.
  4. 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