GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2001 🢒 LeSabre 🢒 Body and Accessories 🢒 Body Control System 🢒 DTC B1000

Circuit Description

The instrument panel integration module (IPM) communicates with the HVAC control module via the signal data bus and the clock signal data bus for the driver HVAC control assembly. This communication link is only used by the IPM and the HVAC control module.

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC
    • There is a loss of communications between the IPM and the HVAC control module.
    • The above conditions are present for 3 seconds.

Action Taken When the DTC Sets

The heater and A/C system will be disabled.

Conditions for Clearing the DTC
    • The DTC will become history if the IPM no longer detects a failure.
    • The history DTC will clear after 50 fault free ignition cycles.
    • The DTC can be cleared with a scan tool.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step verifies that the HVAC control module is functioning, but not communicating with the IPM.

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the display of the HVAC control module.

Are all of the visual indicators illuminated and is the audible indicator ON?

--

Go to Step 7

Go to Step 3

3
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the display of the HVAC control module.

Is the display of the HVAC control module blank?

--

Go to Step 5

Go to Step 4

4

  1. Turn ON the ignition, with the engine OFF.
  2. Observe the display of the HVAC control module.

Does the HVAC control module display only °C (°F)?

--

Go to Step 8

Go to Testing for Intermittent Conditions and Poor Connections

5
  1. Turn OFF the ignition.
  2. Disconnect the HVAC control module.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the ignition 3 voltage circuit of the HVAC control module and a good ground.

Does the test lamp illuminate?

--

Go to Step 6

Go to Step 10

6

Connect a test lamp between the ignition 3 voltage circuit and the ground circuit (connector pin location A1) of the HVAC control module.

Does the test lamp illuminate?

--

Go to Step 15

Go to Step 11

7
  1. Turn OFF the ignition.
  2. Disconnect the HVAC control module.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage between the driver HVAC control assembly signal circuit of the HVAC control module and a good ground.

Does the voltage measure near the specified value?

1 V

Go to Step 15

Go to Step 12

8
  1. Turn OFF the ignition.
  2. Disconnect the HVAC control module.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage between the driver HVAC control assembly signal circuit of the HVAC control module and a good ground.

Does the voltage measure near the specified value?

1 V

Go to Step 9

Go to Step 13

9

Measure the frequency between the driver HVAC control assembly clock signal circuit of the HVAC control module and a good ground.

Does the frequency measure near the specified value?

930 Hz

Go to Step 15

Go to Step 14

10

Test the ignition 3 voltage circuit of the HVAC control module for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

--

11

Test the ground circuit (connector pin location A1) of the HVAC control module for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

--

12

Test the driver HVAC control assembly signal circuit for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 16

13

Test the driver HVAC control assembly signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 14

14

Test the driver HVAC control assembly clock signal circuit for a short to voltage, a short to ground, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 16

15

Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 17

16

Inspect for poor connections at the harness connector of the instrument panel integration module (IPM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 18

17

Replace the HVAC control module. Refer to HVAC Control Module Replacement .

Did you complete the replacement?

--

Go to Step 19

--

18

Important: : Perform the Recalibration procedure for the instrument panel integration module.

Replace the instrument panel integration module. Refer to Instrument Panel Module Replacement in Body Control System.

Did you complete the replacement?

--

Go to Step 19

--

19
  1. Use the scan tool in order to clear the DTCs .
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK