GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The power roof module monitors the power roof motor hall effect sensors during roof motor operation. When the roof module detects that there are no hall sensor pulses or there is a difference of greater than 80 counts between sensor 1 and 2, a DTC is set.

Conditions for Setting the DTC

The power roof module detects that there are no hall sensor pulses or there is a difference of greater than 80 counts between sensor 1 and 2.

Action Taken When the DTC Sets

    • Stores a current DTC B3972 in roof module memory
    • Stores a history DTC B3972 in roof module memory

Conditions for Clearing the DTC

    • The roof module no longer detects a current DTC B3972 in roof module memory.
    • The DTC is cleared using a scan tool.

Diagnostic Aids

    • The following conditions may cause an intermittent malfunction:
       - There is an intermittent sticking or binding condition in the roof causing the roof to be unable to move.
       - The roof motor is shorted internally.
    • If the DTC does not reset after the code is cleared, then the problem may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The number below refers to the step number on the diagnostic table.

  1. Tests the window for a sticking or binding condition.

Step

Action

Yes

No

Schematic Reference: Sunroof Schematics

Connector End View Reference: Power Roof Systems Connector End Views

1

Did you perform the Power Roof Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Power Roof

2

Observe the driver information center (DIC).

Does the DIC display Open Roof or Close Roof?

Go to Step 5

Go to Step 3

3

Inspect the roof for a sticking or binding condition.

Did you find and correct the condition?

Go to Step 5

Go to Step 4

4

Test the hall effect reference, signal and return circuits 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 7

Go to Step 5

5

Inspect for poor connections at the harness connector of the power roof motor. 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 7

Go to Step 6

6

  1. Perform the power roof relearn procedure. Refer to Power Roof Relearn .
  2. Replace the power roof motor. Refer to Moveable Roof Panel Motor/Actuator Replacement .

Did you complete the replacement?

Go to Step 7

--

7

  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