Chevrolet Trax: DTC B3873: Front washer relay

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 body control module (BCM) controls the windshield washer based on an input from the windshield washer switch, which is part of the windshield wiper/washer switch. The BCM monitors the windshield washer switch through a discrete signal circuit. When the washer switch is pressed, the signal circuit is pulled to ground. The BCM will respond by commanding the washer function.

The windshield washer uses a single windshield washer pump to provide fluid for both the front and rear washers. Changing the polarity of the motor will cause it to spin in opposite directions, feeding fluid to the front or rear. When front washers are requested, the BCM applies voltage to the windshield washer pump relay control circuit. This causes the contacts in the windshield washer pump relay to close and supplies voltage to the windshield washer pump. Ground for the windshield washer pump is provided through the rear window washer pump relay, which is switched to ground in it's at-rest state.

Conditions for Running the DTC

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

Conditions for Setting the DTC

B3873 01

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

B3873 02

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

B3873 04

An open/high resistance has been detected on 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 Schematics (Encore), Wiper/Washer Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

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 Windshield Washer pump does not activate

If Windshield Washer Pump Activates,

Refer to Circuit/System Testing - Windshield Washer Pump Malfunction

If Windshield Washer Pump does not Activate

3. Verify the scan tool Windshield Washer Switch parameter changes between Active and Inactive when pressing and releasing the washer switch.

If the parameter does not change

Refer to Circuit/System Testing - Washer Switch Malfunction.

If the parameter changes

4. Verify the G24 Windshield Washer Pump activates when commanding the Windshield Washer Relay Active with a scan tool.

If the Windshield Washers do not turn ON

Refer to Circuit/System Testing - Windshield Washer Pump Malfunction

If the Windshield Washers turn ON

All OK.

Circuit/System Testing

Washer Switch Malfunction

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the S82 Windshield Wiper/Washer Switch. It may take up to 11 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the low reference circuit terminal 2 and ground.

If 10 ohms or greater

1. Ignition OFF.
2. Test for less than 2 ohms in the low reference circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 Body Control Module.

If less than 10 ohms

3. Ignition ON.
4. Verify the scan tool Windshield Washer Switch parameter is Inactive.

If not Inactive

1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module.
2. Test for infinite resistance between the signal circuit terminal 5 and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K9 Body Control Module.

If Inactive

5. Install a 3 A fused jumper wire between the signal circuit terminal 5 and the low reference circuit terminal 2.
6. Verify the scan tool Windshield Washer Switch parameter is Active.

If not Active

1. Ignition OFF, remove the jumper wire, disconnect the harness connector at the K9 Body Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V

3. Test for less than 2 ohms in the signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 Body Control Module.

If Active

7. Test or replace the S82 Windshield Wiper/Washer Switch.

Windshield Washer Pump Malfunction

1. Ignition OFF, and all vehicle systems OFF. Disconnect the X2 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 ohms between the ground circuit terminal C5 and ground:

If 10 ohms or greater

1. Test for less than 2 ohms in the ground circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection

If less than 10 ohms

3. Connect the X2 harness connector and disconnect the X1 harness connector at the X50A Fuse Block - Underhood.
4. Test for infinite resistance between each of the control circuit terminals listed below and ground.

• Terminal G3
• Terminal H3

If less than Infinite resistance

Repair the short to ground on the circuit.

If infinite resistance

5. Connect the X1 harness connector at the X50A Fuse Block - Underhood. Disconnect the harness connector at the G24 Windshield Washer Pump, ignition ON.
6. Test for less than 1 V between the control circuit terminals listed below and ground:

• Terminal 1
• Terminal 2

If 1 V or greater

1. Ignition OFF, disconnect the X1 harness connector at the X50A Fuse Block - Underhood.
2. Test for less than 1 V between the control circuit 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.

If less than 1 V

7. Ignition OFF, and all vehicle systems OFF. It may take up to 2 min for all vehicle systems to power down.
8. Test for less than 10 ohms between the control circuit terminal 1 and ground.

If 10 ohms or greater

1. Ignition OFF, disconnect the X1 harness connectors at the X50A Fuse Block - Underhood.
2. Test for less than 2 ohms in the control circuit end to end:

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the X50A Fuse Block - Underhood.

If less than 10 ohms

9. Test for less than 10 ohms between the control circuit terminal 2 and ground.

If 10 ohms or greater

1. Ignition OFF, disconnect the X1 harness connectors at the X50A Fuse Block - Underhood.
2. Test for less than 2 ohms in the control circuit end to end:

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the X50A Fuse Block - Underhood.

If less than 10 ohms

10. Connect a test lamp between the control circuit terminal 1 and the control circuit terminal 2, ignition ON.
11. Verify the test lamp does NOT turn ON and OFF when commanding the rear washer ON and OFF with the rear washer switch.

If the test lamp turns ON and OFF

Test or replace the G24 Windshield Washer Pump.

If the test lamp does not turn ON and OFF

12. Ignition OFF, connect the harness connector at the G24 Windshield Washer Pump. Disconnect the X2 harness connector at the X50A Fuse Block - Underhood, ignition ON.
13. Connect a test lamp between the control circuit terminal G9 and ground.
14. Verify the test lamp turns ON and OFF when commanding the Windshield Washer Relay Active with a scan tool.

If the test lamp is always OFF

1. Ignition OFF, remove the test lamp. Disconnect the X4 harness connector at the K9 Body Control Module.
2. Test for infinite resistance between the control circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance.

3. Test for less than 2 ohms in the control circuit end to end.

• If 2 ohms or greater, repair the short to ground on the circuit.
• If less than 2 ohms, replace the K9 Body Control Module

If the test lamp is always ON

1. Ignition OFF, remove the test lamp. Disconnect the X4 harness connector at the K9 Body Control Module, ignition ON.
2. Test for less than 1 V between the control circuit and ground.

• If 2 ohms or greater, repair the short to voltage on the circuit.
• If less than 2 ohms, replace the K9 Body Control Module

If the test lamp turns ON and OFF.

15. Test or replace the X50A Fuse Block - Underhood.

Component Testing

Washer Switch

1. Ignition OFF, disconnect the harness connector at the S82 Windshield Wiper/Washer Switch.
2. Test for infinite resistance between the signal terminal 5 and the low reference terminal 2 with the switch in the open position.

If less than infinite resistance

Replace the S82 Windshield Wiper/Washer Switch.

If infinite resistance

3. Test for less than 2 ohms between the signal circuit terminal 5 and the low reference circuit terminal 2 with the switch in the closed position.

If 2 ohms or greater

Replace the S82 Windshield Wiper/Washer Switch.

If less than 2 ohms

4. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Front Compartment Fuse Block Replacement
• Windshield Washer Pump Replacement
• Windshield Wiper and Washer Switch Replacement (Encore), Windshield Wiper and Washer Switch Replacement (Trax)
• Control Module References for body control module replacement, programming, and setup.

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