• | 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. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Front Auxiliary HVAC Control Assembly B+ | 1 | 1 | -- | -- |
Rear Auxiliary HVAC Control Assembly B+ | 2 | 2 | -- | -- |
Auxiliary Mode Actuator Ignition | 1, 2 | 1, 2 | -- | -- |
Front Auxiliary Mode Signal | 1 | 1 | 1 | -- |
Rear Auxiliary Mode Signal | 2 | 2 | 2 | -- |
Auxiliary Mode Actuator Control | 1, 2 | 1, 2 | 1, 2 | -- |
Auxiliary Mode Actuator Ground | -- | 1, 2 | -- | -- |
1. Auxiliary Mode Selection Inoperative from Front Control 2. Auxiliary Mode Selection Inoperative from Rear Control |
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 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 module will maintain the control value until a new commanded value is needed.
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. |
⇒ | If the blower motor is inoperative, refer to Auxiliary Blower Motor Malfunction . |
⇒ | If the mode does not change, refer to Mode Malfunction - Front Auxiliary Control. |
⇒ | If the blower motor is inoperative, refer to Auxiliary Blower Motor Malfunction . |
⇒ | If the mode does not change, refer to Mode Malfunction - Rear Auxiliary Control. |
⇒ | If the blower motor is inoperative, refer to Auxiliary Blower Motor Malfunction . |
⇒ | If the air temperature does not change, refer to Mode Malfunction without Rear Auxiliary Control. |
⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. |
⇒ | If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the front auxiliary HVAC control assembly. |
⇒ | 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 voltage does not change as specified, replace the auxiliary HVAC control assembly. |
⇒ | 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 less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the rear auxiliary HVAC control assembly. |
⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. |
⇒ | 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 voltage does not change as specified, replace the front auxiliary HVAC control assembly. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.