GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2009 🢒 Yukon - 4WD 🢒 DTC 🢒 DTC B1023

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 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.

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 or shorted 5 volt reference circuit.

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 Temperature Description and OperationAir Temperature Description and Operation
    •  Air Delivery 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. 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.
    2. ⇒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.
    3. ⇒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.
    6. ⇒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