GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 Eldorado 🢒 Transmission/Transaxle 🢒 Automatic Transaxle - 4T80-E 🢒 Diagnostic System Check - Automatic Transmission Shift Lock Control

Test Description

The number(s) below refer to the step number(s) 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 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

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.
    3. 2.1. Body Control Module (PZM).
    2.2. Powertrain Control Module (PCM).

Does the scan tool communicate with both the PZM and PCM?

Go to Step 3

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

3

With a scan tool select the display DTC function for the following modules.

  1. Body Control Module (PZM).
  2. Powertrain Control Module (PCM).

Does the scan tool display any DTCs?

Go to Step 4

Go to Symptoms - Automatic Transmission Shift Lock Control

4

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

5

Does the scan tool display DTC B1552, B1556 or B1558?

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

Go to Step 6

6

Does the scan tool display DTC B2502, B2503, P0719 or P0724?

Go to Diagnostic Trouble Code (DTC) List/Type

Go to Symptoms - Automatic Transmission Shift Lock Control