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

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. The symptom list in Symptoms will determine the correct diagnostic procedure to use.

    3.

  3. The presence of DTCs U1016, U1064, U1255 or U1300 indicates the memory mirror module (MMM) is not communicating on the class 2 serial data circuit.

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:
    3. • Body Control Module (BCM)
    • Memory Mirror Module (MMM)
    • Powertrain Control Module (PCM)

Does the scan tool communicate with the listed 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 Class 2 Power Mode in the Diagnostic Circuit Check on the scan tool.
  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?

Go to Step 4

Go to Power Mode Mismatch in Body Control System

4

Select the Memory Mirror Module display DTCs function on the scan tool.

Does the scan tool display any DTCs?

Go to Step 5

Go to Symptoms - Doors

5

Does the scan tool display DTCs U1016, U1064, U1255 or U1300?

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 B1656 or B1658?

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

Go to Step 7

7

Does the scan tool display DTC B2130, B2131, B2132 or B2133?

Go to Diagnostic Trouble Code (DTC) List in Seats

Go to Diagnostic Trouble Code (DTC) List