Rain Sensor Malfunction
Rain Sensor Malfunction
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 B370A 39
- Rain Sensor Internal Malfunction
Diagnostic Fault Information
Circuit/System Description
B+ voltage is supplied to the Rain Sensor. Whenever the ignition is ON, or accessory positions, the body control module (BCM), sends the turn signal/multifunction switch status by using a pulse width modulated (PWM) signal. When a wipe cycle is needed, the Rain Sensor sends a PWM voltage signal to the BCM, requesting the wiper operation. The BCM commands the Windshield Wiper Motor wipe cycles. If at anytime a fault occurs between the Rain 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 system voltage is between 9-16 V.
Action Taken When the DTC Sets
* If the BCM loses communication with the Rain Sensor while the Rain Sensor is 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 Rain Sensor while the Rain Sensor is continuously requesting low, it shall fail soft the wipers operation to front wiper manual - low.
* If the BCM loses communication with the Rain Sensor while the Rain Sensor is 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 Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Wiper/Washer System Description and Operation Description and Operation
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 Verification
1. Ignition ON.
2. Verify the wipers operate at low speed when the Windshield Wiper Switch is in the LOW position.
• If the wipers are not operating at low speed
Refer to Windshield Wiper System Malfunction Windshield Wiper System Malfunction.
• If the wipers are operating at low speed
3. Place the Windshield Wiper Switch in the delay mode/moisture sensitivity settings Delay 1 through Delay 5 and spray the outside of the windshield in the rear view mirror/Rain Sensor region with a water bottle.
4. Verify the wipers operate at low speed.
• If the wipers are not operating at low speed
Refer to Circuit/System Testing.
• If the wipers are operating at low speed
5. All OK.
Circuit/System Testing
1. Ignition OFF, all vehicle systems OFF, disconnect the harness connector at the B117 Rain Sensor. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal 3 and ground.
• If 10 ohms or greater
1. Ignition OFF.
2. 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. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 1 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF, remove the test lamp.
2. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF, remove the test lamp.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the B117 Rain Sensor.
• If the test lamp illuminates
4. Ignition OFF, remove the test lamp, ignition ON.
5. Test for 4.0-12.0 V between the serial data circuit terminal 2 and ground.
• If less than 4.0 V
1. Ignition OFF, disconnect the harness connector at the K9 body control module.
2. Test for infinite resistance between the serial data 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 serial data 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 greater than 12.0 V
1. Ignition OFF, disconnect the harness connector at the K9 body control module, ignition ON.
2. Test for less than 1 V between the serial data circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K9 body control module.
• If between 4.0-12.0 V
6. Replace the disconnected B117 Rain Sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Windshield Outside Moisture/Ambient Light and Humidity Sensor Replacement Service and Repair
* Control Module References Control Module References for BCM replacement, programming and setup