GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The instrument panel integration module (IPM) monitors the ambient light on the left and right side of the vehicle via a light sensitive photodiode which is called a sunload sensor assembly. The IPM uses this information to compensate for the effect of the sun on the inside air temperature of the vehicle. When the sensor is in direct sunlight, the signal voltage is low. When the sensor is shaded, the signal voltage is high. The IPM requests A/C compressor clutch engagement and controls the air temperature door positions in order to maintain the selected air temperature on the HVAC control module.

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

A default value of 0 counts will be substituted for the solar sensor data by the IPM. The Left Solar or Right Solar displayed on the scan tool in the HVAC Sensors data list will be the default value. The Left Solar Sensor or Right Solar Sensor displayed on the scan tool in the Open/Short Data list will be the actual value.

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.

Test Description

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

  1. The operating range of the sensor is between 0.09-4.90 volts. If the scantool displays a value between 0-.08V or 4.91-5.0 volts, then the sensor is performing outside of its designed limits.

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

  3. 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.

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 Right or Left Solar Sensor parameter in the Instrument Panel Module Open/Short Data list.

Does the scan tool indicate that the Solar Sensor parameter is with in the specified range?

0.09-4.90 V

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the sunload sensor assembly.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Right and Left Solar Sensor parameters in the Instrument Panel Module Open/Short Data list.

Does the scan tool indicate that the Solar Sensor parameters are greater than the specified value?

4.90 V

Go to Step 4

Go to Step 5

4

  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper wire between the left or right signal circuit of the sunload sensor and the low reference circuit of the sunload sensor assembly.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Right or Left Solar Sensor parameter in the Instrument Panel Module Open/Short Data list.

Does the scan tool indicate that the Solar Sensor parameter is less than the specified value?

0.09 V

Go to Step 8

Go to Step 6

5

Test the right or left signal circuit of the sunload sensor assembly 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 12

Go to Step 9

6

Test the right or left signal circuit of the sunload sensor assembly 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 12

Go to Step 7

7

Test the low reference circuit of the sunload sensor assembly 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 12

Go to Step 9

8

Inspect for poor connections at the harness connector of the sunload sensor assembly. 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 12

Go to Step 10

9

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 12

Go to Step 11

10

Replace the sunload sensor assembly. Refer to Sunload and Twilight Sentinel Sensor Replacement in Instrument Panel, Gauges and Console.

Did you complete the replacement?

--

Go to Step 12

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11

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 12

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12

  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