Service Information

Cruze

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. Windscreen Outside Moisture Sensor Malfunction

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

Action Taken When the DTC Sets

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

•	If the BCM looses communication with the windscreen outside moisture sensor while the windscreen 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

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

Ignition ON, S82 Windscreen Wiper/Washer Switch in the low position. The windscreen wipers should operate at low speed.

⇒	If the windscreen wipers do not operate, refer to Windscreen Wiper System Malfunction .

Circuit/System Testing

Ignition OFF, disconnect the harness connector at the B117 Rain Sensor.
Test for less than 5 Ω between the ground circuit terminal 2 and ground.

⇒	If greater than the specified value, test the ground circuit for an open/high resistance.

Ignition ON, verify that a test lamp illuminates between B+ voltage circuit terminal 1 and ground.

⇒	If the test lamp does not illuminate, test the B+ voltage circuit for a short to ground or an open/high resistance.

Ignition ON, test for 4-12 V between the signal circuit terminal 3 and ground.

⇒	If less than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.

If all circuits test normal, replace the B117 Rain Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Windscreen Outside Moisture Sensor Replacement

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