DTC P0571. GMC Truck TopKick C-Series Commercial (Cutaway) C6/C7/C8 2005

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2005 🢒 TopKick C-Series Commercial (Cutaway) C6/C7/C8 🢒 DTC 🢒 DTC P0571

DTC P0571 6.6L

Circuit Description

The torque converter clutch (TCC) brake switch/cruise control release signal circuit is incorporated into the stop lamp switch. The TCC brake switch/cruise control release signal circuit portion of the stop lamp switch is a normally closed switch. The stop lamp switch signal circuit portion of the stop lamp switch is a normally open switch. When the brake pedal is released, the engine control module (ECM) detects a high voltage signal on the TCC brake switch/cruise control release signal circuit and a low signal voltage signal on the stop lamp switch signal circuit.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0571 (6.6L) Cruise Control Brake Switch Circuit

Conditions for Running the DTC

•	The engine speed is greater than 700 RPM.

•	The engine operates for greater than 2 seconds.

•	The wheel speed is greater than 48 km/h (30 mph) in order to enable the diagnostic. The diagnostic disables when the wheel speed is below 16 km/h (10 mph).

Conditions for Setting the DTC

•	When the brake pedal is released, the ECM detects a high voltage signal on the stop lamp switch signal circuit or when the ECM detects a low voltage signal on the TCC brake switch/cruise control release signal circuit.

•	The above conditions are present for 2 seconds.

Action Taken When the DTC Sets

•	The ECM stores the DTC information into memory when the diagnostic runs and fails.

•	The malfunction indicator lamp (MIL) will not illuminate.

•	The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.

Conditions for Clearing the DTC

•	A last test failed, or current DTC, clears when the diagnostic runs and does not fail.

•	A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.

•	Use a scan tool in order to clear the DTC.

Diagnostic Aids

•	Refer to Exterior Lighting Systems Description and Operation in order to avoid a misdiagnosis.

•	For an intermittent, refer to Testing for Intermittent Conditions and Poor Connections .

Step	Action	Yes	No
Schematic Reference: Cruise Control Schematics 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	Turn OFF the ignition. Disconnect the stop lamp switch. Turn ON the ignition, with the engine OFF. Connect a test lamp between the stop lamp switch signal circuit and a good ground. Does the test lamp illuminate?	Go to Step 3	Go to Step 4
3	Test the stop lamp switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 9	Go to Step 6
4	Test the torque converter clutch (TCC) brake switch/cruise control release signal circuit for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 9	Go to Step 5
5	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 . Did you find and correct the condition?	Go to Step 9	Go to Step 7
6	Inspect for poor connections at the harness connector of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	Go to Step 9	Go to Step 8
7	Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement . Did you complete the repair?	Go to Step 9	--
8	Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?	Go to Step 9	--
9	Use a scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC. Does the DTC reset?	Go to Step 2	System OK

DTC P0571 7.8L

Circuit Description

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0571 (7.8L) Cruise Control Brake Switch Circuit

Conditions for Running the DTC

•	The ignition is ON.

•	The traction control system (TCS) or the antilock brake system (ABS) have not failed.

Conditions for Setting the DTC

•	When the brake pedal is released, the ECM detects a high voltage signal on the stop lamp switch signal circuit or when the ECM detects a low voltage signal on the TCC brake switch/cruise control release signal circuit.

•	The above conditions are present for 1.5 seconds.

Action Taken When the DTC Sets

•	The ECM stores the DTC information into memory when the diagnostic runs and fails.

•	The malfunction indicator lamp (MIL) will not illuminate.

•	The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.

Conditions for Clearing the DTC

•	A last test failed, or current DTC, clears when the diagnostic runs and does not fail.

•	A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.

•	Use a scan tool in order to clear the DTC.

Diagnostic Aids

•	Refer to Exterior Lighting Systems Description and Operation in order to avoid a misdiagnosis.

•	For an intermittent, refer to Testing for Intermittent Conditions and Poor Connections .

Step	Action	Yes	No
Schematic Reference: Cruise Control Schematics 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	Turn OFF the ignition. Disconnect the stop lamp switch. Turn ON the ignition, with the engine OFF. Connect a test lamp between the stop lamp switch signal circuit and a good ground. Does the test lamp illuminate?	Go to Step 3	Go to Step 4
3	Test the stop lamp switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 9	Go to Step 6
4	Test the torque converter clutch (TCC) brake switch/cruise control release signal circuit for an open or for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 9	Go to Step 5
5	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 . Did you find and correct the condition?	Go to Step 9	Go to Step 7
6	Inspect for poor connections at the harness connector of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	Go to Step 9	Go to Step 8
7	Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement . Did you complete the repair?	Go to Step 9	--
8	Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?	Go to Step 9	--
9	Use a scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC. Does the DTC reset?	Go to Step 2	System OK

DTC P0571 8.1L

Circuit Description

The torque converter clutch (TCC) brake switch/cruise control release signal circuit is incorporated into the stop lamp switch. The TCC brake switch/cruise control release signal circuit portion of the stop lamp switch is a normally closed switch. The stop lamp switch signal circuit portion of the stop lamp switch is a normally open switch. When the brake pedal is released, the powertrain control module (PCM) detects a high voltage signal on the TCC brake switch/cruise control release signal circuit and a low signal voltage signal on the stop lamp switch signal circuit.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0571 (8.1L) Cruise Control Brake Switch Circuit

Conditions for Running the DTC

•	The engine speed is greater than 700 RPM.

•	The engine operates for greater than 2 seconds.

•	The wheel speed is greater than 48 km/h (30 mph) in order to enable the diagnostic. The diagnostic disables when the wheel speed is below 16 km/h (10 mph).

Conditions for Setting the DTC

•	When the brake pedal is released, the PCM detects a high voltage signal on the stop lamp switch signal circuit or when the PCM detects a low voltage signal on the TCC brake switch/cruise control release signal circuit.

•	The above conditions are present for 2 seconds.

Action Taken When the DTC Sets

•	The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails.

•	The malfunction indicator lamp (MIL) will not illuminate.

•	The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.

Conditions for Clearing the DTC

•	A last test failed, or current DTC, clears when the diagnostic runs and does not fail.

•	A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.

•	Use a scan tool in order to clear the DTC.

Diagnostic Aids

•	Refer to Exterior Lighting Systems Description and Operation in order to avoid a misdiagnosis.

•	For an intermittent, refer to Testing for Intermittent Conditions and Poor Connections .

Step	Action	Yes	No
Schematic Reference: Cruise Control Schematics 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	Turn OFF the ignition. Disconnect the stop lamp switch. Turn ON the ignition, with the engine OFF. Connect a test lamp between the stop lamp switch signal circuit and a good ground. Does the test lamp illuminate?	Go to Step 3	Go to Step 4
3	Test the stop lamp switch signal circuit for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 9	Go to Step 6
4	Test the torque converter clutch (TCC) brake switch/cruise control release signal circuit for an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 9	Go to Step 5
5	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 . Did you find and correct the condition?	Go to Step 9	Go to Step 7
6	Inspect for poor connections at the harness connector of the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	Go to Step 9	Go to Step 8
7	Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement . Did you complete the repair?	Go to Step 9	--
8	Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?	Go to Step 9	--
9	Use a scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC. Does the DTC reset?	Go to Step 2	System OK