For 1990-2009 cars

### 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 B370C 00: Rain Sensor Intensity Signal Circuit.
DTC B370D 00: Rain Sensor Mode Control Circuit.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Ignition Voltage | 1 | 1 | 1 | --
Outside Moisture Sensor Signal 1 | B370D | B370D | 1 | --
Outside Moisture Sensor Signal 2 | B370C | B370C | 1 | --
Ground | -- | 1 | -- | --
1. Moisture sensing feature is inoperative

### Circuit/System Description

Ignition voltage is supplied to the windshield outside moisture sensor from the body control module (BCM). Whenever the ignition is in the run or accessory positions, the BCM sends the wiper/washer switch status using a pulse width modulated (PWM) signal through the windshield outside moisture sensor signal 1 circuit to the outside moisture sensor. When a wipe cycle is needed, the moisture sensor sends a PWM voltage signal through the moisture sensor signal 2 circuit back to the BCM requesting the wiper operation.

The windshield outside moisture sensor uses the moisture sensor signal 2 circuit to command wiper motor wipe cycles and to confirm the moisture sensor signal 1 is being received. If at anytime communication between the windshield outside moisture sensor and BCM is lost, the BCM will use the inputs from the windshield wiper/washer switch in the delay positions to operate the wiper motor at continuous variable delay intervals.

### Conditions for Running the DTC

The ignition is in the Run or Accessory positions.

### Conditions for Setting the DTC

#### B370C

An open, short to ground or a short to voltage has been detected on moisture sensor signal 2 circuit.

#### B370D

An open, short to ground or a short to voltage has been detected on moisture Sensor Signal 1 circuit.

### Action Taken When the DTC Sets

Moisture sensitive wiper operation is suspended so long as the fault is present. The wipers will still operate normally in all other modes.

### Conditions for Clearing the DTC

• | A current DTC will clear when the fault is no longer present.

• | A history DTC will clear after 40 malfunction-free ignition cycles.

### 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

Ignition ON, wiper switch in the LOW position. The windshield wipers should operate at low speed. If the windshield wipers do not operate, refer to Windshield Wiper System Malfunction.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the windshield outside moisture sensor.
2. Test for less than 5.0 ohms between the ground circuit terminal 3 and ground.

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

3. Ignition ON, verify that a test lamp illuminates between ignition voltage circuit terminal 4 and ground.

⇒ | If the test does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

4. Ignition ON, test for 4.0 - 8.5 volts between the signal circuit terminal 2 and ground.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the windshield outside moisture sensor.

⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the windshield outside moisture sensor.

5. Ignition OFF, connect the harness connector at the windshield outside moisture sensor.
6. Disconnect the X4 harness connector at the BCM.
7. Ignition ON, test for 8.0 - 10.0 volts between the signal circuit terminal 14 and ground.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the windshield outside moisture sensor.

⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the windshield outside moisture sensor.

8. If all circuits test normal, replace the BCM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

For BCM replacement, setup, and programming, refer to Control Module References.