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 B1020 00: No Communication with Rain Sensor.
DTC B1020 71: Invalid Data from Rain Sensor.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Rain sensor B+ | 2 | 2 | 1 | --
Rain sensor Signal circuit | -- | 1, 2, 3 | -- | DTC B1020:71
Rain sensor Ground | -- | 1 | -- | --
1. Rain sence on at all times. 2. Rain sence inoperative.

### Circuit/System Description

B+ is supplied to the rain sensor through circuit 139 from the Underhood Electrical Center (UEC). The rain sensor communicates with the UEC over circuit 481. the rain sensor sends data over this circuit to determine wiper speed when wipers are set to intermittent operation. The rain sensor is grounded by circuit 1550.

### Conditions for Running the DTC

• | Ignition is on.

• | Wipers are requested on.

### Conditions for Setting the DTC

B1020:00

Communication error between UEC and rain sensor or the communication with the UEC is interrupted.

B1020:71

Invalid data exchange between rain sensor and UEC

### Action Taken When the DTC Sets

Rainsence feature is disabled, wipers still operate in all other manual settings

### 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.

### 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 intermittent position. Spray water on the windshield just above the rain sensor Verify the windshield wipers are cycling at an appropriate speed.

Install scan tool, with the ignition ON engine OFF monitor rain sensor communication status, should display Okay.

With scan tool monitor rain sensor status. Status should toggle between Active and Inactive when the ignition is cycled from ON to OFF.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the rain sensor.
2. Ignition ON, verify a test lamp illuminates between the control circuit terminal 1 and ground.

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

3. verify a test lamp illuminates between the control circuit terminal 1 and ground terminal 2.

⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

4. Ignition OFF, Remove UEC, Ignition ON, Measure voltage between rain sensor terminal 3 and ground. Verify there is less than 0.3 volts

⇒ | If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the UEC.

5. Ignition OFF, measure resistance between rain sensor harness terminal 3 and Ground. Verify resistance is greater than 500 KOhm

⇒ | If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the rain sensor.

### Repair Instructions

Perform the Diagnostic Repair Verificationafter completing the diagnostic procedure.

• | Windshield Outside Moisture Sensor Replacement

• | Control Module Referencesfor UEC replacement, setup, and programming