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Chevrolet Silverado / GMC Sierra. Manual - part 2349
Recirculation Door Ignition
B0228 02
B0228 05
B0228 05
B0228 61
Recirculation 5-Volt
Reference
B0228 02,
B0413 02,
B0423 02 or
B3779 02
B0228 05
B0228 02,
B0413 02,
B0423 02 or
B3779 02
B0228 61
Recirculation Door Position
Signal
B0228 02
B0228 05
B0228 05
B0228 61
Recirculation Door Control
B0228 02
B0228 05
B0228 05
B0228 61
Recirculation Low
Reference
B0228 02
B0228 05
B0228 05
B0228 61
Driver Air Temperature
Door Ignition
B0413 02
B0413 05
B0413 05
B0413 61
Driver Air Temperature 5-
Volt Reference
B0228 02,
B0413 02,
B0423 02 or
B3779 02
B0413 05
B0228 02,
B0413 02,
B0423 02 or
B3779 02
B0413 61
Driver Air Temperature
Door Position Signal
B0413 02
B0413 05
B0413 05
B0413 61
Driver Air Temperature
Door Control
B0413 02
B0413 05
B0413 05
B0413 61
Driver Air Temperature Low
Reference
B0413 02
B0413 05
B0413 05
B0413 61
Passenger Air Temperature
Door Ignition
B0423 02
B0423 05
B0423 05
B0423 61
Passenger Air Temperature
5-Volt Reference
B0228 02,
B0413 02,
B0423 02 or
B3779 02
B0423 05
B0228 02,
B0413 02,
B0423 02 or
B3779 02
B0423 61
Passenger Air Temperature
Door Position Signal
B0423 02
B0423 05
B0423 05
B0423 61
Passenger Air Temperature
Door Control
B0423 02
B0423 05
B0423 05
B0423 61
Passenger Air Temperature
Low Reference
B0423 02
B0423 05
B0423 05
B0423 61
Mode Door Ignition
B3779 02
B3779 05
B3779 05
B3779 61
Mode 5-Volt Reference
B0228 02,
B0413 02,
B3779 05
B0228 02,
B0413 02,
B3779 61
2008 Chevrolet Silverado 1500
2008 HVAC HVAC - Manual - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Circuit/System Description
The HVAC control module controls the HVAC door actuators to regulate the airflow through the
HVAC system. Each actuator consists of an electric motor and a potentiometer. The module
supplies a low reference and 5-volt reference source voltage to the potentiometer. The HVAC
control module monitors the voltage drop across the potentiometer on the door position signal
circuit. When the actuator shaft rotates, the voltage on the door position signal circuit changes.
The control circuit uses either a 0, 2.5 or 5-volt signal to command the actuator movement. When
the actuator is at rest, the control circuit value is 2.5 volts. A 0 or 5-volt control signal commands
the actuator movement in opposite directions.
B0228 is for the recirculate actuator.
B0413 is for the drivers air temperature actuator.
B0423 is for the passenger air temperature actuator.
B3779 is for the mode actuator.
Conditions for Running the DTC
Ignition ON.
The HVAC module is ON.
Conditions for Setting the DTC
The actual door position differs from the commanded door position by more than 4 counts or the
HVAC control module detects the door position signal circuit is less than 3 counts or greater than
253 counts.
Action Taken When the DTC Sets
The control circuit is deactivated for the appropriate actuator.
Conditions for Clearing the DTC
The DTC becomes history when the HVAC control module no longer detects the condition
that set the DTC.
B0423 02 or
B3779 02
B0423 02 or
B3779 02
Mode Door Position Signal
B3779 02
B3779 05
B3779 05
B3779 61
Mode Door Control
B3779 02
B3779 05
B3779 05
B3779 61
Mode Low Reference
B3779 02
B3779 05
B3779 05
B3779 61
2008 Chevrolet Silverado 1500
2008 HVAC HVAC - Manual - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
The history DTC will clear after 100 fault-free ignition cycles.
Reference Information
Schematic Reference
HVAC Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Air Delivery Description and Operation
Air Temperature 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, command the appropriate actuator in both directions with a scan tool. The scan tool
door position parameter reading should be between 3 and 253 counts.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the appropriate actuator.
2. Test for less than 1 ohm between the low reference circuit terminal 7 and ground.
If greater than the specified range, test the low reference circuit for an open/high
resistance. If the circuit tests normal, replace the HVAC control module.
3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 10 and
2008 Chevrolet Silverado 1500
2008 HVAC HVAC - Manual - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
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.
4. Verify the appropriate scan tool parameter is less than 4 counts.
If greater than the specified range, test the signal circuit terminal 9 for a short to
ground. If the circuit tests normal, replace the HVAC control module.
5. Install a 3-amp fused jumper wire between the signal circuit terminal 9 and the low
reference circuit terminal. Verify the appropriate scan tool parameter is greater than 250
counts.
If less than the specified range, test the signal circuit for a short to voltage or an
open/high resistance. If the circuit tests normal, replace the HVAC control module.
6. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 5 and
ground.
If the test lamp does not illuminate, test the ignition circuit for a short to ground or an
open/high resistance.
7. Install a DMM between the actuator control circuit terminal 6 and ground. While
monitoring the DMM, use the scan tool to command the appropriate actuator from one
direction to the other. The voltage on the control circuit should move from 0 volts in one
direction to 5 volts in the other direction and 2.5 volts in the at rest state.
If the voltage does not change, test the control circuit for an open, short to voltage or
short to ground. If circuit tests normal replace the HVAC control module.
8. If all circuits test normal, replace the actuator.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Air Temperature Actuator Replacement - Right Side
Air Temperature Actuator Replacement - Left Side
Mode Actuator Replacement
Recirculation Actuator Replacement
DTC P0532 OR P0533
Diagnostic Instructions
2008 Chevrolet Silverado 1500
2008 HVAC HVAC - Manual - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Content .. 2347 2348 2349 2350 ..