GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The power roof module (PRM) provides power and ground for the power roof motor control. The PRM applies power and ground to the roof motor control circuits depending on the desired direction. If the roof module detects a short to ground or an open in a roof motor control circuit, a DTC is set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B3973 Moveable Roof Motor Circuits

Conditions for Setting the DTC

The roof module detects a short to ground or an open in a roof motor control circuit.

Action Taken When the DTC Sets

    • Stores a current DTC B3973 in roof module memory
    • Stores a history DTC B3973 in roof module memory

Conditions for Clearing the DTC

    • The roof module no longer detects a short to ground or an open in a roof motor control circuit.
    • 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 motor thermal protection to open.
       - 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 numbers below refer to the step numbers on the diagnostic table.

  1. This step tests the roof for proper operation. If the roof sticks or binds, this condition must be repaired first.

Step

Action

Yes

No

Schematic Reference: Sunroof Schematics

Connector End View Reference: Power Roof Systems Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Inspect the roof for a sticking or binding condition.

Did you find and correct the condition?

Go to Step 6

Go to Step 3

3

Test the power roof motor control circuits for 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 6

Go to Step 4

4

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 6

Go to Step 5

5

  1. Perform the power roof relearn procedure. Refer to 136878.
  2. Replace the power roof motor. Refer to Moveable Roof Panel Motor/Actuator Replacement .

Did you complete the replacement?

Go to Step 6

--

6

  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