GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 Blazer - 4WD - RHD 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Diagnostic System Check - Theft Deterrent

Diagnostic Aids

You must diagnose the diagnostic trouble codes (DTCs) in the order specified in the DTC list. Failure to do so may result in the following conditions:

    • Extended diagnostic time
    • Incorrect diagnosis
    • Incorrect parts replacement

If the BCM, the Passlock™ sensor, the VCM or the PCM have been replaced, perform the learn procedure before following the diagnostic system check.

Refer to the instrument panel section for additional information on the message center display. Carefully follow the steps within the Theft Deterrent Diagnostic System Check.

Test Description

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

  1. 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.

  2. Tests for an open in the Passlock™ sensor signal circuit which may not set a DTC (B2958) under certain conditions.

    3.

  3. 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.

Step

Action

Value(s)

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 Body Control Module (BCM) and the Instrument Panel Cluster (IPC).

Does the scan tool communicate with the BCM and the IPC?

--

Go to Step 3

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

3

Select the Body Control Module display DTCs function on the scan tool.

Does the scan tool display any DTCs?

--

Go to Step 5

Go to Step 4

4

  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.

Does the scan tool display OPEN?

--

Go to DTC B2958 Security System Sensor Data Circuit High

Go to Symptoms

5

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 6

6

Does the scan tool display DTC [B2947, B2948, B2957, B2958, B2960, B2961, B2973, B3031, or B3033]?

--

Go to Diagnostic Trouble Code (DTC) List/Type

Go to Diagnostic Trouble Code (DTC) List/Type in Body Control System