B3874

DTC B3874

Diagnostic Instructions

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

DTC Descriptor
DTC B3874 00
- Wiper Low Speed Relay Circuit

Diagnostic Fault Information






Circuit/System Description

The body control module (BCM) monitors the wiper Low speed relay control circuit only when wiper Low speed mode is active. When the wiper Low speed mode is requested, the BCM responds by applying a ground through the wiper Low speed relay control circuit to the coil side of the relay, energizing the WPR Relay.

Conditions for Running the DTC

This DTC can set only when the output is actively being requested by the BCM.

Conditions for Setting the DTC

This DTC sets if the BCM detects a short to battery voltage in the wiper relay control circuit.

Action Taken When the DTC Sets

The BCM will not activate the output.

Conditions for Clearing the DTC

* The current DTC will become history when the request for the output is removed or when the condition for setting the fault is corrected.
* The history DTC will clear after 50 consecutive ignition cycles without a fault present.

Reference Information
Schematic Reference

Wiper/Washer Schematics Electrical Diagrams
Connector End View Reference

Component Connector End Views
Description and Operation

Wiper/Washer System Description and Operation Wiper/Washer System
Electrical Information Reference

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

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Testing

1. Ignition OFF, remove the WPR Relay from the underhood fuse block.
2. Connect a test lamp between the wiper Low speed relay control circuit terminal 86 and battery voltage.
3. Ignition ON, command the Wiper Relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

• If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, test or replace the BCM.

• If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the BCM.

4. If all circuits test normal, test or replace the WPR relay.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

Control Module References Control Module References for BCM replacement, setup, and programming