GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2006 🢒 Vibe - AWD 🢒 Restraints 🢒 SIR 🢒 DTC P0571

Circuit Description

When the brake pedal is depressed, the stop light switch sends a signal to the powertrain control module (PCM). When the PCM receives this signal, it cancels the cruise control.

When the stop light switch is ON, the battery positive voltage is applied through the STOP fuse and stop light switch to the PCM.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0571 Brake Switch Circuit 1

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

Stop light switch does not turn OFF when the vehicle is being driven.

Action Taken When the DTC Sets
    • The PCM illuminates the malfunction indicator lamp (MIL) the first time the diagnostic runs with the fault active.
    • The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC
    • The MIL turns OFF after 3 consecutively passing trips without a fault present.
    • A History DTC clears after 40 consecutive warm-up cycles without a fault.
    • Use the scan tool Clear DTC Information function.

Diagnostic Aids

A scan tool should indicate the state of the stop light switch.

An intermittent malfunction may be caused by a fault in the stop lamp electrical circuit. Inspect the wiring harness and the components for any of the following conditions:

    • Any backed-out terminals
    • Any improper mating of terminals
    • Any broken electrical connector locks
    • Any improperly formed or damaged terminals
    • Any faulty terminal-to-wire connections
    • Any physical damage to the wiring harness
    • A broken wire inside the insulation
    • Any corrosion of the electrical connections, the splices, or the terminals

Repair any electrical circuit faults that were found. Refer to Wiring Repairs in Wiring Systems.

Test Description

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

  1. This step monitors the state of the stop lamp switch as detected by the PCM.

    2.

  2. This step checks continuity of the stop lamp switch internal contacts.

    3.

  3. This step checks for battery positive voltage at the stop lamp switch.

    4.

  4. This step checks the state of the stop lamp switch input to the PCM.

Step

Action

Values

Yes

No

Schematic Reference: Cruise Control Schematics

Connector End View Reference: Cruise Control Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn the ignition to OFF.
  2. Connect a scan tool to the data link connector (DLC).
  3. Turn the ignition to ON.
  4. Use the scan tool data list to monitor the stop lamp switch state while repeatedly depressing the brake pedal.

Does the scan tool display as specified?

Brake Pedal Depressed: ON

Brake Pedal Released: OFF

Go to Step 11

Go to Step 3

3
  1. Turn the ignition to OFF.
  2. Disconnect the stop lamp switch wiring harness connector.
  3. Inspect the stop lamp switch for proper adjustment and inspect the switch wiring harness connector for damage.

Did you find and complete the repair?

--

Go to Step 13

Go to Step 4

4

Test for continuity of the stop lamp switch terminals 1 and 2 while repeatedly pressing the brake pedal.

Is the value as specified?

Pedal Depressed: No Continuity

Pedal Released: Continuity

Go to Step 5

Go to Step 12

5

Test for continuity of the stop lamp switch terminals 3 and 4 while repeatedly pressing the brake pedal.

Is the value as specified?

Pedal Depressed: Continuity

Pedal Released: No Continuity

Go to Step 6

Go to Step 12

6

  1. Turn the ignition to ON.
  2. Using a test lamp, test for battery positive voltage at terminal 2 of the stop lamp switch wiring harness connector.

Did the test lamp illuminate?

--

Go to Step 7

Go to Step 10

7

  1. Turn the ignition to OFF.
  2. Reconnect the stop lamp switch wiring harness connector.
  3. Turn the ignition to ON.
  4. Monitor the voltage at the stop lamp switch input, terminal x, of the powertrain control module (PCM) to a known good ground while repeatedly depressing and releasing the brake pedal.

Is the value as specified?

Depressed: 10-14 V

Released: Less than 1 V

Go to Step 8

Go to Step 9

8

Monitor the voltage at the stop lamp switch input, terminal x1, of the PCM to a known good ground while repeatedly depressing and releasing the brake pedal.

Is the value as specified?

Depressed: Less than 1 V

Released: 10-14 V

Go to Step 11

Go to Step 9

9

Repair and open or short to ground in the stop lamp circuits between the stop lamp switch and the PCM. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 13

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10

Repair an open in the battery positive circuit between the stop lamp switch and the battery. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair

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Go to Step 13

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11

Replace the PCM. Refer to Powertrain Control Module Programming and Setup in Programming and Setup.

Is the replacement complete?

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Go to Step 13

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12

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

Is the replacement complete?

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Go to Step 13

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13
  1. Perform the scan tool Clear DTC Information function and road test the vehicle with the Freeze Frame conditions that set the DTC.
  2. Review the scan tool data and check for DTCs. The repair is complete if no DTCs are stored.

Are any DTCs displayed on the scan tool?

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Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

System OK