GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2001 🢒 Bonneville 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 DTC B0234

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.

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.

Conditions for Running the DTC
    • The ignition is turned ON.
    • The instrument panel integration module (IPM) power must be interrupted.
    •  Perform the Recalibrate all Motors command using the scan tool.

Conditions for Setting the DTC

The left air temperature actuator actual total travel range (max-min) is less than or greater than the calibrated limits.

Action Taken When the DTC Sets
    • The instrument panel integration module (IPM) will continue to make use of whatever left air temperature actuator travel range is still available.
    • Each time the ignition switch is turned ON the instrument panel integration module (IPM) will perform a recalibration of the actuator.

Conditions for Clearing the DTC

The left air temperature actuator travel range error must be corrected.

Diagnostic Aids
    • The range fault code can only be detected following a check of the left air temperature actuator travel range. The left air temperature actuator travel range check can only be initiated by disrupting power to the instrument panel integration module (IPM) (disconnecting the battery) or with the scan tool.
    • The calibration limit is 152-220 counts (3.0-4.4 V). An actual range below this limit suggests an obstruction (something stuck in the door limiting travel). An actual range above this limit suggests an over travel condition (damaged or missing foam seals). If the condition is present, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

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 Min Left Temp Dr Pos and Max Left Temp Dr Pos parameters in the Instrument Panel Module HVAC Door Calibrations data list.
  4. 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?

152-220 counts

Go to Diagnostic Aids

Go to Step 3

3

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

Did you find and correct the condition?

--

Go to Step 13

Go to Step 4

4

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 13

Go to Step 5

5

Test the 5 volt reference circuit of the left air temperature actuator for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 6

6

Important: Ensure that the left air temperature actuator control module and the instrument panel integration module control assembly connector is 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 Instrument Panel Module 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 (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 (drives the actuator full COOL).

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

--

Go to Step 7

Go to Step 9

7
  1. Measure the voltage from the left air temperature door control circuit of the left air temperature actuator to 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?

0V decreasing 5V increasing 2.5V stationary

Go to Step 8

Go to Step 10

8

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

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

Did you find and correct the condition?

--

Go to Step 13

Go to Diagnostic Aids

9

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 13

Go to Step 11

10

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 13

Go to Step 12

11

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 13

--

12

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 13

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13
  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