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Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. 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. 5:  Tests for an open in the passlock sensor signal circuit which may not set a DTC B2958 under certain conditions.
  3. 6:  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. 7:  The presence of DTC P0601, P0602, P0604, or P0606 indicates an internal fault in the PCM.
  5. 8:  The presence of DTC B1000 indicates an internal module fault.
  6. 9:  The presence of DTC P1637, P1638, P0562 or P0563 indicates a low or high voltage condition.
Diagnostic System Check - Theft Deterrent

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
2 
  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the following control modules:
    • Powertrain control module (PCM)
    • Body control module (BCM)
    • Instrument panel cluster (IPC)
Does the scan tool communicate with the all the listed control modules?		 Go to Step 3  Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications
3
IMPORTANT: Important: The engine may start during the following step. Turn OFF the engine as soon as you have observed the Crank power mode.
  1. Access the Class 2 Power Mode parameter in the Diagnostic Circuit Check menu on the scan tool.
    2. IMPORTANT: Insure that all ignition switch positions are observed including the OFF position.
  2. Rotate the ignition switch through all positions while observing the Class 2 Power Mode parameter.
Does the Class 2 Power Mode parameter reading match the ignition switch position for all switch positions?		 Go to Step 4  Go to Power Mode Mismatch in Body Control System
4 Select the display DTCs function on the scan tool for the following control modules:
  • Powertrain Control Module (PCM)
  • Body Control Module (BCM)
  • Instrument Panel Cluster (IPC)

Does the scan tool display any DTCs?		 Go to Step 6  Go to Step 5 
5  1. Momentarily rotate the ignition switch to CRANK. Do not start the vehicle.
2. Release the ignition switch to ON.
3. With a scan tool, observe the Passlock Code in the Body Control Module Security Data list.
Dose the scan tool display OPEN?		 Go to DTC B2958  Go to Symptoms - Theft Deterrent 
6  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 7 
7  Does the scan tool display DTC P0601, P0602, P0604, or P0606? Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 6.6L Go to Step 8 
8  Does the scan tool display DTC B1000? Go to DTC B1000 in Body Control System Go to Step 9 
9  Does the scan tool display DTC P1637, P1638, P0562 or P0563? Go to Diagnostic Trouble Code (DTC) List in Engine Electrical Go to Diagnostic Trouble Code (DTC) List 
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