GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 Envoy - 2WD 🢒 DTC 🢒 DTC B3964 and B3965

Circuit Description

The endgate module controls operation of the endgate window motor by supplying ground for the endgate window regulator down signal and endgate window regulator up signal circuits. These circuits are used to enable the endgate window motor relays. If the endgate module detects a short to ground or voltage on the endgate window regulator down signal or endgate window regulator up signal circuits, a DTC is set.

Conditions for Setting the DTC

The endgate module detects a short to ground or voltage on the endgate window regulator down signal or endgate window regulator up signal circuits.

Action Taken When the DTC Sets
    • Stores a current DTC B3964 or B3965 in endgate module memory.
    • Stores a history DTC B3964 or B39650 in endgate module memory.

Conditions for Clearing the DTC
    • The endgate module no longer detects a current DTC B3964 or B3965 in endgate module memory.
    • The DTC is cleared using a scan tool.

Diagnostic Aids
    • An intermittent short to ground or voltage in the endgate window up or down relay may cause an intermittent malfunction.
    • 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 for a short to ground or voltage in the endgate window regulator down signal and endgate window regulator up signal circuits.

Step

Action

Yes

No

Schematic Reference: Body Rear End Schematics

Connector End View Reference: Body Rear End Connector End Views

1

Did you perform the Body Rear End Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Body Rear End

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the endgate window Up and Down.

Does the endgate window go Up and Down?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Test the endgate window regulator down signal and endgate window regulator up signal circuits for a short to ground or voltage. 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 endgate window regulator. 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 endgate window learn procedure. Refer to Endgate Window Learn Cycle
  2. Replace the endgate window regulator. Refer to Endgate Window Regulator 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