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. |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Auxiliary Mode Actuator Ignition | 1 | 1 | -- | -- |
Auxiliary Mode Actuator Control | 1 | 1 | 1 | -- |
Auxiliary Mode Actuator Ground | -- | 1 | 1 | -- |
1. Auxiliary Mode Actuator Inoperative | ||||
Circuit/System Description
The auxiliary mode actuator is a 3-wire bi-directional electric motor. Ignition 3 voltage, ground and control circuits enable the actuator to operate. The control circuit uses a 0-12 volts linear-ramped signal to command the actuator movement. The 0 and 12-volt control values represent the opposite limits of the actuator range of motion. The values in between 0 and 12 volts correspond to the positions between the limits.
When the auxiliary HVAC control assembly sets a commanded, or targeted, value, the control signal is set to a value between 0-12 volts. The actuator shaft rotates until the commanded position is reached. The auxiliary HVAC control assembly will maintain the control value until a new commanded value is needed.
Diagnostic Aids
Inspect the auxiliary mode door and the auxiliary mode actuator for the following conditions:
| • | A misaligned auxiliary mode actuator. |
| • | Broken or binding linkages or auxiliary mode door. |
| • | An obstruction that prevents the auxiliary mode door from operating within its full range of motion. |
| • | Missing seals to the auxiliary mode door. |
| • | Misaligned seals to the auxiliary mode door. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, engine running, place the auxiliary blower motor switch at the maximum speed position and the front mode switch in the vent or panel position.
- Press the auxiliary mode control switch from the upper position to the lower position. The auxiliary mode actuator should follow the commanded states.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the auxiliary mode actuator.
- Test for less than 1.0 ohm between the auxiliary mode actuator ground circuit terminal 3 and ground.
- Ignition ON, verify that a test lamp illuminates between the auxiliary mode actuator ignition circuit terminal 1 and ground.
- Install a DMM between the control circuit terminal 2 and ground. Command the actuator in each direction. Voltage on the control circuit should change from 0 volts when commanding the actuator in one direction to 12 volts in the other direction.
- If all circuits test normal, test or replace the auxiliary mode actuator.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, replace the auxiliary mode actuator. |
| ⇒ | If the voltage does not change as specified, replace the HVAC control module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for auxiliary HVAC control module replacement, setup, and programming |
