B0424

DTC B0424

CIRCUIT DESCRIPTION
- B0130 is for the mode actuator.
- B0414 is for the driver air temperature actuator.
- B0424 is for the passenger air temperature actuator.

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 potentiometer inside the door actuator allows the module to monitor the current position of the actuator drive shaft. The module supplies a 5 volt source voltage to the potentiometer on the 5 volt reference circuit. The module supplies ground to the potentiometer through the low reference circuit. 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.

CONDITIONS FOR SETTING THE DTC
The HVAC control module detects the door position signal circuit is less than 7 counts or greater than 250 counts for 1 minute.

ACTION TAKEN WHEN THE DTC SETS
The HVAC control module uses only the minimum and maximum door positions.

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.
- The DTC can be cleared with a scan tool.

DIAGNOSTIC AIDS
- If the condition is not present.
- The following conditions may cause multiple DTCs to set:
- An open, short to ground or short to voltage on the 5 volt reference circuit.
- An open on the low reference circuit
- An internally shorted actuator
- An insufficient 5 volt supply from the HVAC control module on the 5 volt reference circuit
- An insufficient ground through the HVAC control module on the low reference circuit

TEST DESCRIPTION

Steps 1-4:

Steps 5-7:

Steps 8-12:

Steps 13-18:

The numbers below refer to the step numbers on the diagnostic table.
4. Tests for the proper operation of the circuit in the high voltage range.
5. Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.
6. Tests for a short to ground in the 5 volt reference circuit.