B3873

DTC B3873

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

DTC Descriptor
DTC B3873 00 Front Wiper Relay Drive Circuit

Diagnostic Fault Information






Circuit/System Description
The body control module (BCM) controls the washer motor based on an input from the windshield wiper washer switch. The BCM monitors the washer switch through the windshield washer switch signal circuit. When the WASH switch is closed, ground is supplied to the windshield washer switch signal circuit. When this is seen, the BCM will command the windshield washer fluid pump and the low speed wipers on.

Conditions for Running the DTC
A washer request is present

Conditions for Setting the DTC
A short to voltage is detected in the windshield washer relay control circuit

Action Taken When the DTC Sets
Washer operation is suspended

Conditions for Clearing the DTC
^ A current DTC will clear when the condition for setting the fault is no longer seen
^ A history DTC will clear after 50 consecutive ignition cycles without a fault present

Circuit/System Verification
Operate the washers using the WASH switch. Verify the washer pump activates.

Circuit/System Testing
1. Ignition OFF, disconnect the C3 harness connector at the underhood fuse block.
2. Connect a test lamp between the control circuit terminal 25 and B+.
3. Ignition ON, command the washers ON and OFF using the WASH switch. 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, 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, replace the BCM.

4. If all circuits test normal, replace the underhood fuse block.

Repair Instructions
Perform the [Diagnostic Repair Verification - Vehicle Diagnostic Information] after completing the diagnostic procedure Diagnostic Repair Verification - Vehicle Diagnostic Information
^ [Underhood Electrical Center or Junction Block Replacement]
^ [Control Module References] for BCM replacement, setup, and programming Programming and Relearning