GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 DeVille 🢒 Body and Accessories 🢒 Wiring Systems 🢒 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. Determine if the Powertrain Control Module, Instrument Panel Integration Module, Dash Integration Module or Rear Climate Control have set DTC's which may affect HVAC operation are present.

    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.

    4.

  4. Answer Yes if the first three characters of the DTC name begins with B10; regardless of the last two characters. If a B1009 code is set, answer No to the question.

    5.

  5. Be sure to follow the diagnostic table for B1009 in the HVAC Systems-Automatic section. Do not use the table in Body Control System.

Step

Action

Yes

No

1

Did you review A Diagnostic Starting Point - Heating, Ventilation and Air Conditioning?

Go to Step 2

Go to Diagnostic Starting Point

2

Install a scan tool.

Does the scan tool power up?

Go to Step 3

Go to Scan Tool Does Not Power Up in Data Link Communications

3

  1. Turn ON the ignition, with the engine OFF.
  2. Establish communication with the following control modules:
    3. • Powertrain control module
    • Instrument panel integration module
    • Dash integration module
    • Rear climate control

Does the scan tool communicate with the control modules?

Go to Step 4

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

4

Select the display DTCs function on the scan tool for the following control modules:

    • Powertrain Control Module
    • Instrument Panel Integration Module
    • Dash Integration Module
    • Rear Climate Control

Does the scan tool display any DTCs?

Go to Step 5

Go to Symptoms

5

Does the scan tool display any DTCs that 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 B10XX, except B1009?

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

Go to Step 7

7

Does the scan tool display DTC B1327 or B1328?

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

Go to Step 8

8

Does the scan tool display any DTCs that are not associated with the HVAC system?

Go to Diagnostic Trouble Code (DTC) List/Type in Engine Controls - 4.6 L

Go to DTC Table