GM Service Manual Online
For 1990-2009 cars only

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.

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

The instrument panel integration module (IPM) detects the signal circuit is less than 0.05 volt (3 counts) or greater than 4.90 volts (250 counts).

Action Taken When the DTC Sets

    • A default value of 2.50 volts (128 counts) will be substituted for the left air temperature door position data by the instrument panel integration module (IPM) .
    • The instrument panel integration module (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.

Conditions for Clearing the DTC

    • The DTC will become history if the instrument panel integration module (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

    • 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 (overtravel condition). The internal stops are outside of the feedback potentiometers 0-250 count working range.
    • If the condition is present, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

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. 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. 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 Instrument Panel Module HVAC Door Positions data list.

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

0.05-4.90 V

Go to Diagnostic Aids

Go to Step 3

3

  1. With a scan tool, command the Left Temp Dr position from Hot to Cold.
  2. With a scan tool, observe the Left Temp Dr Actual parameter in the Instrument Panel Module HVAC Door Positions data list.

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

--

Go to Step 12

Go to Step 4

4

  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?

4.90 V

Go to Step 5

Go to Step 9

5

  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?

0.05 V

Go to Step 6

Go to Step 10

6

  1. Turn OFF the ignition
  2. Disconnect the fused jumper wire.
  3. Connect a 3 amp fused jumper wire between the left air temperature door position signal circuit and the 5 volt reference 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?

4.90 V

Go to Step 8

Go to Step 7

7

Test the 5 volt reference 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 17

Go to Step 14

8

Test the 5 volt reference 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 17

Go to Step 13

9

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 17

Go to Step 14

10

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 17

Go to Step 11

11

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 17

Go to Step 14

12

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 17

Go to Step 13

13

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 17

Go to Step 15

14

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 17

Go to Step 16

15

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 17

--

16

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 17

--

17

  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