2010 Cadillac CTS Sedan AWD V6-3.6L Page 228

2010 Cadillac CTS Sedan AWD V6-3.6L Page 228

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 HVAC module controls the direction of the actuator door by changing the polarity of the control

circuits.

* Air Flow Control 3 is the mode actuator

* Air Flow Control 7 is the recirculation actuator

* Temperature Control 1 is the left temperature actuator

* Temperature Control 2 is the right temperature actuator

Conditions for Running the DTC

* Ignition ON.

* Ignition voltage is between 9-16 volts.

* 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 7 counts or greater than 250 counts.

Action Taken When the DTC Sets

Control A and control B circuits are 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.

* The history DTC will clear after 50 fault-free ignition cycles.

Reference Information

Schematic Reference

HVAC Schematics (See: Heating and Air Conditioning/Diagrams/Electrical Diagrams)

Connector End View Reference

Component Connector End Views (See: Diagrams/Connector Views)

Description and Operation

Automatic HVAC Description and Operation (See: Heating and Air Conditioning/Description and Operation/HVAC - Automatic)

Electrical Information Reference

* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)

* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)

* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit

Testing/Testing for Intermittent Conditions and Poor Connections)

* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)

Scan Tool Reference

Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information

Circuit/System Verification

Ignition ON, command the appropriate actuator to 100 percent with a scan tool. The scan tool should display between 224 and 230 counts on the

mode actuator, all other actuators should display between 199 and 205 counts.

Circuit/System Testing

1. Ignition OFF, disconnect the X1 harness connector at the HVAC control module.

2. Ignition ON, Verify that a test lamp illuminates between the B+ circuit terminal 18 and ground.

瀚慖f the test lamp does not illuminate, test the B+ circuit for an short to ground or a open/high resistance.

3. Ignition OFF, connect the harness connector at the HVAC control module and disconnect the harness connector at the appropriate actuator.

4. Ignition OFF, test for less than 10 ohms between the following low reference circuit terminal and ground.