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DTC B370A

DTC B370A

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 B370A 39

Rain Sensor Internal Malfunction

Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
Rain Sensor B+ 1 1 - -
Rain Sensor Signal B370A 39 B370A 39 B370A 39 B370A 39
Rain Sensor Ground - 1 1 -
1. Windshield Outside Moisture Sensor Malfunction


Circuit/System Description

B+ voltage is supplied to the windshield outside moisture sensor. Whenever the ignition is ON, or in accessory positions, the body control module (BCM), sends the wiper/washer switch status by using a pulse width modulated (PWM) signal. When a wipe cycle is needed, the windshield outside moisture sensor sends a PWM voltage signal to the BCM, initiating the wiper operation. The BCM commands the windshield wiper motor wipe cycles. If a fault occurs at any time between the windshield outside moisture sensor and BCM, the BCM will use the inputs from the turn signal/multifunction switch in the delay positions to operate the windshield wiper motor at continuous variable delay intervals.

Conditions for Running the DTC


• Ignition ON.

• The system voltage is between 9-16 V.


Conditions for Setting the DTC

The BCM receives an invalid signal from the windshield outside moisture sensor.

Action Taken When the DTC Sets


• If the BCM loses communication with the windshield outside moisture sensor while the windshield outside moisture sensor was requesting single wipes, it shall fail soft the wipers operation to front wiper manual-intermittent with a fixed dwell time of 4 seconds.

• If the BCM loses communication with the windshield outside moisture sensor while the windshield outside moisture sensor was continuously requesting low, it shall fail soft the wipers operation to front wiper manual-low.

• If the BCM loses communication with the windshield outside moisture sensor while the windshield outside moisture sensor was continuously requesting high, it shall fail soft the wipers operation to front wiper manual-high.


Conditions for Clearing the DTC

A current DTC clears when the diagnostic runs and passes.

Reference Information

Schematic Reference

Wiper/Washer Schematics

Connector End View Reference

Component Connector End Views

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

If this DTC is set, replace the B117 rain sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


• Windshield Outside Moisture Sensor Replacement

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