GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2002 🢒 Park Avenue 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 DTC B1344

Circuit Description

The instrument panel integration module (IPM) commands mode actuator movement with one of three voltage signals applied to the mode door control circuit. A low voltage of 0 volts moves the mode door toward the defrost position. 2.5 volts stops the actuator. 5 volts moves the mode door toward the A/C position. The IPM determines the current position of the actuator by monitoring the feedback voltage of the mode door position signal circuit. The feedback potentiometer position is a function of the actuator position. The IPM controls the mode door position in order to maintain the selected mode on the HVAC control module.

Whenever the IPMs keep alive memory battery power is interrupted, the IPM will perform a recalibration of the actuators. The IPM will perform a travel range comparison of the calculated minimum and maximum extremes of the actuator to the calibrated minimum and maximum range extremes within the IPM. If the calculated range does not equal the calibrated expected range the actuator will be considered not calibrated and the DTC will set. The IPM will also perform a continuous test on the current feedback value. If the feedback value does not equal or fall within the calibrated range the DTC will set.

Conditions for Running the DTC
    • The ignition is turned ON.
    • The IPMs keep alive memory (KAM) battery power must be interrupted to run the range check. This can be accomplished with the scan tool by commanding HVAC Recalibration in Heating and Air Conditioning Special Functions.

Conditions for Setting the DTC

The mode actuators total travel range (max-min) is less than or greater than the calibrated limits.

Action Taken When the DTC Sets
    • A default value of will be substituted for the mode door position data by the IPM.
    • Each time the ignition switch is turned ON, the IPM will recheck the actuator travel range.
    • The IPM will continue to make use of whatever travel range is still available.

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
    • The range fault can only be detected following a check of the actuator travel range. The actuator travel range check can only be initiated by disrupting power to the IPM.
    • The calibration limit is 215-245 counts. An actual range below this limit suggests an obstruction or something stuck in the door limiting travel. An actual range above this limit suggests an over travel condition such as damaged or missing foam seals.
    • A damaged or broken mode door and or actuator can cause this DTC to set by allowing the actuator shaft to rotate unrestricted to its internal stop. The internal stops are outside of the working range of the feedback potentiometers 0-250 count.

Test Description

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

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

    2.

  2. 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.

    3.

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

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

1

Did you perform the HVAC Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Htr./Def./A/C Dr. Actual parameter in the Heating and Air Conditioning HVAC Door Positions data list.

Does the scan tool indicate that the Htr./Def./A/C Dr. Actual parameter is within the specified range?

0.06-4.84 V

Go to Step 3

Go to Step 4

3
  1. With the scan tool, observe the Max.Htr./Def./A/C Dr. Pos data parameter and the Min.Htr./Def./A/C Dr. Pos data parameter in the Heating and Air Conditioning HVAC Door Calibrations data list.
  2. Subtract the Min.Htr./Def./A/C Dr. Pos from the Max.Htr./Def./A/C Dr. Pos.

Does the result of the calculation indicate that the actual travel of the mode actuator is within the specified range?

165-195 counts

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 14

4
  1. With a scan tool, command the Htr./Def./A/C actuator from Defrost to A/C.
  2. With a scan tool, observe the Htr./Def./A/C Dr. Actual parameter.

Does the scan tool indicate that the Htr./Def./A/C Dr. Actual parameter changes when the mode actuator is commanded from Defrost to A/C?

--

Go to Step 5

Go to Step 6

5

Inspect the mode door for a condition allowing excessive travel of the actuator.

Did you find and correct the condition?

--

Go to Step 23

Go to Diagnostic Aids

6
  1. Turn OFF the ignition.
  2. Disconnect the mode actuator.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Htr./Def./A/C Dr. Actual parameter.

Does the scan tool indicate that the Htr./Def./A/C Dr. Actual parameter is greater than the specified value?

4.75 V

Go to Step 7

Go to Step 11

7
  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper wire between the mode door position signal circuit and the low reference circuit of the mode actuator.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Htr./Def./A/C Dr. Actual parameter.

Does the scan tool indicate that the Htr./Def./A/C Dr. Actual parameter is less than the specified value?

0.25 V

Go to Step 8

Go to Step 12

8

  1. Turn OFF the ignition.
  2. Disconnect the fused jumper wire.
  3. Connect a 3-amp fused jumper wire between the 5 volt reference circuit and the mode door position signal circuit of the mode actuator.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, observe the Htr./Def./A/C Dr. Actual parameter.

Does the scan tool indicate that the Htr./Def./A/C Dr. Actual parameter is greater than the specified value?

4.75 V

Go to Step 10

Go to Step 9

9

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

Did you find and correct the condition?

--

Go to Step 23

Go to Step 12

10

Test the 5 volt reference circuit of the mode actuator for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 11

11

Test the mode door position signal circuit of the mode actuator for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 12

12

Test the a mode door position signal circuit of the mode actuator for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 13

13

Test the low reference circuit of the mode actuator for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 20

14

Test the ignition 3 voltage circuit of the mode actuator for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 15

15

Test the mode door control circuit of the mode actuator for an open, high resistance, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 16

16

Important: Ensure that the mode actuator connector and the instrument panel integration module connector are connected during this step in order to avoid misdiagnosis.

  1. Turn ON the ignition, with the engine OFF.
  2. With the scan tool, observe the Htr./Def./A/C Dr. Actual data parameter.
  3. Connect a 3-amp fused jumper wire between the mode door control circuit and the 5 volt reference circuit of the mode actuator. This drives the actuator to the A/C position.
  4. Remove and reconnect the jumper wire between the mode door control circuit and the low reference circuit of the mode actuator. This drives the actuator to the defrost position.

Does the mode actuator drive shaft rotate and do the counts change?

--

Go to Step 17

Go to Step 19

17
  1. Measure the voltage from the mode door control circuit of the mode actuator and a good ground.
  2. With a scan tool, command the Htr./Def./A/C actuator to Defrost and then to A/C.

Does the voltage measure near the specified value for each commanded state?

0 V defrost

5 V A/C

2.5 V stationary

Go to Step 18

Go to Step 20

18

Inspect the mode door and the mode actuator for the following conditions:

    • A misaligned mode actuator. Refer to Mode Actuator Replacement .
    • Broken or binding linkages
    • A broken or a binding mode door
    • An obstruction that prevents the mode door from operating within it's full range of motion
    • Missing seals to the mode door
    • Misaligned seals to the mode door

Did you find and correct the condition?

--

Go to Step 23

Go to Diagnostic Aids

19

Inspect for poor connections at the harness connector of the mode actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 21

20

Inspect for poor connections at the harness connector of the instrument panel integration module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 22

21

Important: : Perform the recalibration procedure for the mode actuator.

Replace the mode actuator. Refer to Mode Actuator Replacement .

Did you complete the replacement?

--

Go to Step 23

--

22

Important: : Perform the recalibration procedure for the instrument panel integration module.

Replace the instrument panel integration module. Refer to Instrument Panel Module Replacement in Body Control System.

Did you complete the replacement?

--

Go to Step 23

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23
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK