DTC B0237, B0252, B0272, or B0282. Buick LeSabre 2003

For 1990-2009 cars only

Makes 🢒 Buick 🢒 2003 🢒 LeSabre 🢒 DTC 🢒 DTC B0237, B0252, B0272, or B0282

Circuit Description

The following DTCs are for the HVAC door actuators:

•	B0237-- Left air temperature actuator

•	B0252 -- Mode actuator

•	B0272 -- Recirculation actuator

•	B0282 -- Right air temperature actuator

The instrument panel module (IPM) controls the HVAC door actuators to regulate the airflow through the HVAC system. Each actuator is a 5 wire bi-directional electric motor that incorporates a feedback potentiometer. Ignition 3 voltage, low reference, control, 5 volt reference and position signal circuits enable the actuator to operate. 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. When the actuator shaft rotates, the potentiometer's adjustable contact changes the door position signal between 0-5 volts. The IPM converts the voltage values to count values where 1 V is approximately equal to 51 counts. The IPM uses a range of 0-255 counts to index the actuator position. The door position signal voltage is converted to a 0-255 count range. When the module sets a commanded, or targeted, value, the control signal is changed to either 0 or 5 volts depending upon the direction that the actuator needs to rotate to reach the commanded value. As the actuator shaft rotates the changing position signal is sent to the module. Once the position signal and the commanded value are the same, the module changes the control signal to 2.5 volts.

The IPM will perform a continuous test on the current feedback voltage. If the feedback voltage does not equal or fall within the calibrated limits, the DTC will set.

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC

•	Left air temperature actuator

The IPM detects the signal circuit is less than 0.05 volt (3 counts) or more than 4.90 volts (250 counts).

•	Mode actuator

The IPM detects the signal circuit is less than 0.1 volt (5 counts) or more than 4.90 volts (250 counts).

•	Recirculation actuator

The IPM detects the signal circuit is less than 0.1 volt (5 counts) or more than 4.90 volts (250 counts).

•	Right air temperature actuator

The IPM detects the signal circuit is less than 0.09 volt (5 counts) or more than 4.90 volts (250 counts).

Action Taken When the DTC Sets

•	Left air temperature actuator

-	A default value of 2.50 volts (128 counts) will be substituted for the left air temperature door position data by the IPM.

-	The IPM will toggle the actuator between full hot and full cold in an attempt to maintain the selected air temperature on the HVAC control module.

•	Mode actuator

-	The IPM will only direct airflow from either the vent or defrost outlets.

-	If B0252 sets during a calibration/recalibration event, the IPM will no longer issue commands to the actuator and will not perform a calibration/recalibration until the door position feedback fault is corrected.

•	Recirculation actuator

-	The recirculation actuator will be set to the outside air position.

-	If B0272 sets during a calibration/recalibration event, the IPM will no longer issue commands to the actuator and will not perform a calibration/recalibration until the door position feedback fault is corrected.

•	Right air temperature actuator

-	A default value of 2.50 volts (128 counts) will be substituted for the right air temperature door position data by the IPM.

-	The IPM will toggle the actuator between full hot and full cold in an attempt to maintain the selected air temperature on the HVAC control module.

Conditions for Clearing the DTC

•	The DTC will become history if the IPM no longer detects a failure.

•	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, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

•	A disconnected or broken door/linkage may also set this DTC during calibration/recalibration by allowing the actuator to travel to its minimum internal stops, creating an over travel condition.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

Tests for the HVAC actuator operating within its travel range.

Tests the HVAC actuator for proper operation.

Tests for the proper operation of the circuit in the high voltage range.

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.

Tests for a short to ground in the 5 volt reference circuit.

Step

Action

Values

Yes

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

Did you perform the HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

Install a scan tool.
Turn ON the ignition, with the engine OFF.
With a scan tool, observe the appropriate Dr Actual parameter in the Instrument Panel Module HVAC Door Positions data list.

Does the scan tool indicate that the appropriate Dr Actual parameter is within the specified range?

•	Left air temperature actuator: 0.05-4.90V

•	Mode actuator: 0.25-4.90V

•	Recirculation actuator: 0.25-4.90V

•	Right air temperature actuator: 0.09-4.90V

Go to Diagnostic Aids

Go to Step 3

With a scan tool, command the appropriate actuator.
With a scan tool, observe the appropriate Dr Actual parameter.

Does the scan tool indicate that the appropriate Dr Actual parameter changes when the appropriate door position is commanded?

•	Left Temp Door Position from Hot to Cold

•	Htr./Det./A/C from Deftost to A/C

•	Air Inlet from Recirc. to Outside

•	Right Temp Door Position from Hot to Cold

Go to Step 12

Go to Step 4

Turn OFF the ignition.
Disconnect the appropriate HVAC actuator.
Turn ON the ignition, with the engine OFF.
With a scan tool, observe the appropriate Dr Actual parameter.

Does the scan tool indicate that the appropriate Dr Actual parameter is more than the specified value?

4.90 V

Go to Step 5

Go to Step 9

Turn OFF the ignition.
Connect a 3-amp fused jumper wire between the door position signal circuit and the low reference circuit of the appropriate HVAC actuator.
Turn ON the ignition, with the engine OFF.
With a scan tool, observe the appropriate Dr Actual parameter.

Does the scan tool indicate that the appropriate Dr Actual parameter is less than the specified value?

•	Left air temperature actuator: 0.05V

•	Mode Actuator: 0.25V

•	Recirculation actuator: 0.25V

•	Right air temperature actuator: 0.09V

Go to Step 6

Go to Step 10

Turn OFF the ignition.
Disconnect the fused jumper wire.
Connect a 3-amp fused jumper wire between the door position signal circuit and the 5 volt reference circuit of the appropriate HVAC actuator.
Turn ON the ignition, with the engine OFF.
With a scan tool, observe the appropriate Dr Actual parameter.

Does the scan tool indicate that the appropriate Dr Actual parameter is more than the specified value?

4.90 V

Go to Step 8

Go to Step 7

Test the 5 volt reference circuit of the appropriate HVAC actuator for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.