GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2002 🢒 Eldorado 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Diagnostic System Check - Theft Deterrent

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. 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.

    3.

  3. The listed DTCs are internal module malfunctions and should be corrected before attempting any other diagnostics.

    4.

  4. The listed DTCs are internal module malfunctions and should be corrected before attempting any other diagnostics.

    5.

  5. The listed DTCs are battery voltage related malfunctions and should be corrected before attempting any other diagnostics.

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:
    3. • Instrument Panel Cluster (IPC)
    • Body Control Module (BCM)
    • Powertrain Control Module (PCM)

Does the scan tool communicate with the specified modules?

Go to Step 3

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

3

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 Ignition Switch parameter in the BCM, PCM, and IPC inputs data display lists.
  2. Rotate the ignition switch through all positions while observing the ignition switch power mode parameter.

Does the ignition switch parameter reading match the ignition switch position for all switch positions in each control module?

Go to Step 4

Go to Scan Tool Does Not Communicate with Class 2 Device in Body Control System

4

Select the display DTCs function for each module on the scan tool.

    • Instrument Panel Cluster (IPC)
    • Body Control Module (BCM)
    • Powertrain Control Module (PCM)

Does the scan tool display any DTCs for the modules?

Go to Step 5

Go to Symptoms - Theft Deterrent

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 B1552, B1556, B1557, or B1558?

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

Go to Step 7

7

Does the scan tool display DTC P0601-P0606 or P1621?

Go to Diagnostic Trouble Code (DTC) List in Engine Controls

Go to Step 8

8

Does the scan tool display DTC B1981, B1982 or B1983?

Go to Diagnostic Trouble Code (DTC) List in Engine Electrical

Go to Diagnostic Trouble Code (DTC) List