Buick Regal: DTC B3811

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B3811

Rear Washer Relay Circuit

For symptom byte information, refer to Symptom Byte List.

Diagnostic Fault Information

1. Rear Washer Inoperative.
2. Rear Washer Always ON.

Circuit/System Description

The body control module (BCM) controls the rear washer via a printed circuit board (PCB) relay and based on an input from the rear wiper switch, which is part of the windshield wiper/washer switch. The BCM monitors the rear wiper switch through separate signal circuits and a ground circuit. The rear wiper switch uses a resistor ladder to determine low speed, intermittent, and rear washer operation. The BCM monitors applies and monitors voltage on the rear wiper switch signal circuit. When the rear wiper switch is placed in the low speed, intermittent, or rear washer position, the voltage is pulled down through a different resistor in the resistor ladder, reducing the voltage seen at the BCM. The BCM will respond by commanding the specific rear wiper function.

Conditions for Running the DTC

• Ignition ON
• The system voltage is between 9 - 16 V

Conditions for Setting the DTC

A short to ground has been detected on the rear window washer pump relay control circuit.

B3811 01

A short to voltage has been detected on the rear window washer pump relay control circuit

B3811 02

A short to ground has been detected on the rear window washer pump relay control circuit

B3811 04

A open/high resistance has been detected on the rear window washer pump relay control circuit

Action Taken When the DTC Sets

Rear washer operation is disabled.

Conditions for Clearing the DTC

• A current DTC clears when the diagnostic runs and passes.
• A history DTC will clear after 50 consecutive ignition cycles without a fault present.

Diagnostic Aids

The rear liftgate must be closed in order for the rear wiper to work

Reference Information

Schematic Reference

Wiper/Washer Wiring Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Wiper/Washer System Description and Operation

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information.

Circuit/System Verification

1. Ignition ON.

2. Verify the Rear Window Washers turn On when commanding the Rear Washer Relay Active with a scan tool.

• If the Rear Window Washers do not turn ON

Refer to Circuit/System Testing

• Go to next step: If the Rear Window Washers turn ON

3. All OK.

Circuit/System Testing

1. Ignition OFF and all vehicle systems OFF, disconnect the X1 harness connector at the X50A Fuse Block - Underhood. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 10 Ω between the X50A Fuse Block - Underhood ground circuit terminal 53 and ground.

• If 10 Ω or greater

1. Ignition OFF.
2. Test for less than 2 Ω in the ground circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, repair the open/high resistance in the ground connection.

• Go to next step: If less than 10 Ω

3. Connect the X1 harness connector at the X50A Fuse Block - Underhood and disconnect the X5 harness connector at the K9 Body Control Module, ignition ON.

4. Verify the G24 Windshield Washer Pump is not activated.

• If the G24 Windshield Washer Pump is activated

1. Ignition OFF, disconnect the X2 harness connector at the X50A Fuse Block - Underhood, ignition ON.
2. Test for less than 1 V between the X50A Fuse Block - Underhood control circuit terminal 52 and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • If less than 1 V, test or replace the X50A Fuse Block - Underhood.

• Go to next step: If the G24 Windshield Washer Pump is not activated

5. Connect a 3 A fused jumper wire between the control circuit terminal 11 X5 and B+.

6. Verify the G24 Windshield Washer Pump activates.

• If the G24 Windshield Washer Pump does not activate

1. Ignition OFF, remove the jumper wire, disconnect the X2 harness connector at the X50A Fuse Block - Underhood.
2. Test for infinite resistance between the X50A Fuse Block - Underhood control circuit terminal 52 X2 and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω in the control circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the X50A Fuse Block - Underhood.

• Go to next step: If the G24 Windshield Washer Pump activates

7. Replace the K9 Body Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Engine Wiring Harness Junction Block Replacement (LTG) Engine Wiring Harness Junction Block Replacement (LGX)
• Control Module References for body control module replacement, programming and setup.

DTC B3873

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B3873

Front Washer Relay Circuit

For symptom byte information, refer to Symptom Byte List.

Diagnostic Fault Information

Circuit/System Description

The windshield washer pump is controlled by the body control module (BCM) via a printed circuit board (PCB) relay. When the washer switch is depressed, the BCM's internally pulled high resistor is pulled low by the washer request circuit. The BCM then applies voltage through a control circuit to the PCB windshield washer pump relay.

With the relay energized, fused battery voltage is applied through the switch contacts of the relay and the control circuit to activate the windshield washer fluid pump.

Conditions for Running the DTC

• Ignition ON.
• The system voltage is between 9 - 16 V.

Conditions for Setting the DTC

B3873 01

The body control module detects a short to B+ in the windshield washer pump relay control circuit.

B3873 02

The body control module detects a short to ground in the windshield washer pump relay control circuit.

B3873 04

The body control module detects an open or high resistance in the windshield washer pump relay control circuit.

Action Taken When the DTC Sets

Washer operation is suspended.

Conditions for Clearing the DTC

A current DTC clears when the diagnostic runs and passes.

Reference Information

Schematic Reference

Wiper/Washer Wiring Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Wiper/Washer System Description and Operation

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information.

Circuit/System Verification

1. Ignition ON.

2. Verify the G24 Windshield Washer Pump activates when commanding the Windshield Washer Relay On and Off with a scan tool.

• If the G24 Windshield Washer Pump does not activate

Refer to Circuit/System Testing

• Go to next step: If the G24 Windshield Washer Pump activates

3. All OK.

Circuit/System Testing

1. Ignition OFF, disconnect the X4 harness connector at the K9 Body Control Module, ignition ON.

2. Verify the G24 Windshield Washer Pump is not activated.

• If the G24 Windshield Washer Pump is activated

1. Ignition OFF, disconnect the X2 harness connector at the X50A Fuse Block-Underhood.
2. Test for less than 1 V between the K9 Body Control Module control circuit terminal 14 X4 and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • If less than 1 V, test or replace the X50A Fuse Block-Underhood.

• Go to next step: If the G24 Windshield Washer Pump is not activated

3. Connect a 3 A fused jumper wire between the control circuit terminal 14 and B+.

4. Verify the G24 Windshield Washer Pump activates.

• If the G24 Windshield Washer Pump does not activate

1. Ignition OFF, remove the jumper wire, disconnect the X2 harness connector at the X50A Fuse Block- Underhood, ignition ON.
2. Test for infinite resistance between the control circuit and ground.
   • If less than Infinite resistance, repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω in the control circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, test or replace the X50A Fuse Block-Underhood.

• Go to next step: If the G24 Windshield Washer Pump activates

5. Replace the K9 Body Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Control Module References for body control module replacement, programming and setup.

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