GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2002 🢒 Park Avenue 🢒 DTC 🢒 DTC B1340

Circuit Description

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

Two separate faults can cause this DTC to set:

    • Whenever the IPMs keep alive memory battery power is interrupted, the IPM will perform a recalibration of the actuators. During recalibration, the IPM will drive the actuators to their minimum and maximum travel extremes. The IPM will then calculate a travel range from this data (max-min range) and compare it to a calibrated range within the IPM. If the actual travel range is not within the calibrated expected range, the actuator will be considered not calibrated and the DTC will set.
    •  The IPM also performs 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.
    • 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 IPM detects the left air temperature door position signal circuit is less than 0.25 volt (13 counts) or greater than 4.08 volts (208 counts).
    • The left air temperature 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 2.50 volts (128 counts) will be substituted for the air temperature door position data by the IPM. The IPM will toggle the actuator between full hot and full cool in an attempt to maintain the selected air temperature on the HVAC control module.
    • 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 152-250 counts (2.98-4.90 volts). 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 air temperature 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 feedback potentiometers 0-250 count working range.

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?

--

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 Left Temp Dr. Actual parameter in the Heating and Air Conditioning HVAC Door Positions data list.

Does the scan tool indicate that the Left Temp Dr. Actual parameter is within the specified range?

0.25-4.16 V

Go to Step 3

Go to Step 4

3
  1. With the scan tool, observe the Min Left Temp Dr. Pos data parameter and the Max Left Temp Dr. Pos data parameter in the Heating and Air Conditioning HVAC Door Calibrations data list.
  2. Subtract the Min Left Temp Dr. Pos from the Max Left Temp Dr. Pos.

Does the result of the calculation indicate that the actual travel of the left air temperature actuator is within the specified range?

152-250 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 Left Temp Door Position from Hot to Cold.
  2. With a scan tool, observe the Left Temp Dr. Actual parameter.

Does the scan tool indicate that the Left Temp Dr. Actual parameter changes when the Left Temp Door Position is commanded from Hot to Cold?

--

Go to Step 5

Go to Step 6

5

Inspect the left air temperature door for a condition allowing excessive travel of the actuator.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 6

6

  1. Turn OFF the ignition.
  2. Disconnect the left air temperature actuator.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Left Temp Dr. Actual parameter.

Does the scan tool indicate that the Left Temp Dr. Actual parameter is greater than the specified value?

4.08 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 left air temperature door position signal circuit and the low reference circuit of the left air temperature actuator.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Left Temp Dr. Actual parameter.

Does the scan tool indicate that the Left Temp 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 left air temperature door position signal circuit of the left air temperature actuator.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, observe the Left Temp Dr. Actual parameter.

Does the scan tool indicate that the Left Temp Dr. Actual parameter is greater than the specified value?

4.08 V

Go to Step 10

Go to Step 9

9

Test the 5 volt reference circuit of the left air temperature actuator for a short to ground 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 12

10

Test the 5 volt reference circuit 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 left air temperature door position signal circuit of the left air temperature 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 left air temperature door position signal circuit of the left air temperature 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 left air temperature 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 left air temperature 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 left air temperature door control circuit of the left air temperature 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 left air temperature actuator connector and the IPM 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 Left Temp Dr. Actual data parameter in the Heating and Air Conditioning HVAC Door Positions data list.
  3. Connect a 3-amp fused jumper wire between the left air temperature door control circuit and the 5 volt reference circuit of the left air temperature actuator. This drives the actuator full HOT.
  4. Remove and reconnect the jumper wire between the left air temperature door control circuit and the low reference circuit of the left air temperature actuator. This drives the actuator full COOL.

Does the left air temperature actuator drive shaft rotate and do the counts change?

--

Go to Step 17

Go to Step 19

17
  1. Measure the voltage from the left air temperature door control circuit of the left air temperature actuator and a good ground.
  2. With a scan tool, command the Left Temp Door Position from Hot to Cold.

Does the voltage measure near the specified value when increasing temperature, near the specified value when decreasing temperature and near the specified value when stationary?

0 V decreasing

5 V increasing

2.5 V stationary

Go to Step 18

Go to Step 20

18

Inspect the left air temperature door and the left air temperature actuator for the following conditions:

    • A misaligned air temperature actuator. Refer to Air Temperature Actuator Replacement - Left Side
    • Broken or binding linkages
    • A broken or a binding air temperature door
    • Any obstruction that prevents the air temperature door from operating within it's full range of motion
    • Missing seals to the air temperature door
    • Misaligned seals to the air temperature 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 left air temperature 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 left air temperature actuator.

Replace the left air temperature actuator. Refer to Air Temperature Actuator Replacement - Left Side .

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

--

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