This DTC may be set by an open or shorted 5 volt reference circuit to the auxiliary HVAC control module or an internal fault inside the HVAC control module for a stuck or shorted control button.

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

The HVAC control module has internal fault inside the HVAC control module for a stuck or shorted control button or shorted 5 volt reference circuit.

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, disconnect the harness connector at the auxiliary HVAC control module, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 3 and ground.

⇒	If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC Control Module.

⇒	If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the HVAC Control Module.

2. Reprogram the HVAC control module that set DTC B1023. The module should successfully reprogram.

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

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

⇒	If DTC B1023 sets, replace the module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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