GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2002 🢒 LeSabre 🢒 Body and Accessories 🢒 Body Control System 🢒 Diagnostic System Check - HVAC Systems - Automatic

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. Determine if the Driver Door Module, Powertrain Control Module, Instrument Panel Integration Module or Dash Integration Module have set DTCs 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 B1000 code is set, answer "No" to the question.

    5.

  5. Be sure to follow the diagnostic table for B1000 in the HVAC Systems-Automatic section. Do not use the table in Body Control System. Check History Diagnostic Trouble Code(s) on the scan tool before proceeding.

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 - Heating, Ventilation and Air Conditioning in Heating, Ventilation and Air Conditioning

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. Attempt to establish communication with the following control modules:
    3. • Driver Door Module
    • Powertrain Control Module
    • Instrument Panel Integration Module
    • Dash Integration Module

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

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 5

Go to Power Mode Mismatch in Body Control System

5

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

    • Driver Door Module
    • Powertrain Control Module
    • Instrument Panel Integration Module
    • Dash Integration Module

Does the scan tool display any DTCs?

Go to Step 6

Go to Symptoms - HVAC Systems - Automatic

6

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 7

7

Does the scan tool display DTC B10XX, except B1000?

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

Go to Step 8

8

Does the scan tool display DTC B1327?

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

Go to Step 9

9

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

Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 3.8 L

Go to Diagnostic Trouble Code (DTC) List