Test Description

2001 Chevrolet Chevy Express G3500, Van Passenger Extended, 6.5 FSECTION Test Description
WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 2:  Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
  2. 3:  The Lighting Systems Symptoms will determine the correct diagnostic procedure to use when no DTCs are present.
  3. 4:  The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.
  4. 5:  DTC B1000 and DTC B1001 are internal BCM malfunctions and should be corrected before performing any other diagnostic procedure.
Diagnostic System Check - Lighting Systems

Step Action Yes No
1 Install a scan tool.
Does the scan tool power up?
Go to Step 2  Go to Scan Tool Does Not Power Up in Data Link Communications
  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the body control module (BCM).
Does the scan tool communicate with the BCM?
Go to Step 3  Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications
Select the BCM display DTCs function on the scan tool.
Does the scan tool display any DTCs?
Go to Step 4  Go to Symptoms - Lighting Systems 
Does the scan tool display any DTCs which begin with a "U"? Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications Go to Step 5 
Does the scan tool display DTC B1000 or B1001? Go to Diagnostic Trouble Code (DTC) List in Body Control System Go to Diagnostic Trouble Code (DTC) List 
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.