Diagnostic Aids

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Diagnostic Aids
WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

In order to avoid a misdiagnosis, perform the following:

DTC P0571 (2.2L)

Step Action Yes No
Schematic Reference: Cruise Control Schematics 
Connector End View Reference: Cruise Control Connector End Views  or 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
  1. Turn the ignition OFF.
  2. Install a scan tool.
  3. Turn the ignition ON, with the engine OFF.
  4. With the scan tool, observe the Cruise Brake Switch parameter in the Idle/Speed Control General Info Inputs data list.
Does the Cruise Brake Switch parameter display Released?
Go to Step 3  Go to Step 4 
3
  1. Press and hold the brake pedal.
  2. With the scan tool, observe the Cruise Brake Switch parameter in the Idle/Speed Control General Info Inputs data list.
Does the Cruise Brake Switch parameter display Applied?
Go To Diagnostic Aids  Go to Step 6 
4
  1. Turn the ignition OFF.
  2. Disconnect the cruise/brake switch.
  3. Turn the ignition ON, with the engine OFF.
  4. Connect a test lamp between the ignition 1 voltage circuit and a good ground.
Does the test lamp illuminate?
Go to Step 5  Go to Step 11 
5
  1. Turn the ignition OFF.
  2. Connect a 3-ampere fused jumper between the ignition 1 voltage circuit and the cruise/brake switch signal circuit.
  3. Turn the ignition ON, with the engine OFF.
  4. With the scan tool, observe the Cruise Brake Switch parameter.
Does the Cruise Brake Switch parameter display Released?
Go to Step 9  Go to Step 8 
6
  1. Turn the ignition OFF.
  2. Disconnect the cruise/brake switch.
  3. Turn the ignition ON, with the engine OFF.
  4. With the scan tool, observe the Cruise Brake Switch parameter.
Does the Cruise Brake Switch parameter display Applied?
Go to Step 9  Go to Step 7 
7 Test the cruise/brake switch signal circuit for a short to voltage. Refer Circuit Testing and to Wiring Repairs .
Did you find and correct the condition?
Go to Step 14  Go to Step 10 
8 Test the cruise/brake switch signal circuit for the following:
  • An open
  • A short to ground
  • A high resistance

Refer Circuit Testing and to Wiring Repairs .
Did you find and correct the condition?
Go to Step 14  Go to Step 10 
9 Inspect for poor connections at the harness connector of the cruise/brake switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs .
Did you find and correct the condition?
Go to Step 14  Go to Step 12 
10 Inspect for poor connections at the harness connector of the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs .
Did you find and correct the condition?
Go to Step 14  Go to Step 13 
11 Repair the following in the ignition 1 voltage circuit.
  • An open
  • A short to ground
  • A high resistance

Refer Circuit Testing and to Wiring Repairs .
Did you complete the repair?
Go to Step 14  -
12 Replace the cruise/brake switch. Refer to Cruise Release Switch Replacement .
Did you complete the replacement?
Go to Step 14  -
13 Replace the engine control module (ECM). Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?
Go to Step 14  -
14
  1. Use a scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC.
Does the DTC reset?
Go to Step 2  System OK
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.