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 B1023 05: Integral Switch Performance Short to Ground
DTC B1023 06: Integral Switch Performance Short to Battery or Open
DTC B1023 61: Integral Switch Performance Signal Invalid

### Circuit/System Description

This DTC will be set by internal fault inside the HVAC control module for a stuck or shorted control button.

### Conditions for Running the DTC

Battery voltage is between 9-16 volts and data link communications operate normally.

### Conditions for Setting the DTC

The HVAC control module has internal fault inside the HVAC control module for a stuck or shorted control button.

### Conditions for Clearing the DTC

• | A current DTC clears when the malfunction is no longer present.

• | A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

### Reference Information

#### Schematic Reference

HVAC Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

• | Air Delivery Description and OperationAir Temperature Description and Operation

• | Air Temperature Description and OperationAir Delivery 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

1. Reprogram the HVAC control module. The module should successfully reprogram.

⇒ | If the module will not reprogram, replace the HVAC control module that set the DTC.

2. With a scan tool, clear the DTC.
3. Ignition OFF.
4. Wait 60 seconds, then recheck for DTCs. DTC B1023 should not set.

⇒ | If DTC B1023 sets, replace the module.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module ReferencesControl Module References for control module replacement, setup, and programming