GM Service Manual Online
For 1990-2009 cars only

Circuit Description

This code will set if the output of the sun sensor indicates a probable short circuit or an open in the sensor or the associated wiring harness, or a malfunction of the automatic temperature controller (ATC).

Step

Action

Values

Yes

No

1

  1. Lift the sun sensor from the top of the dashboard.
  2. Secure the automatic temperature controller (ATC) harness below the sun sensor connector so it cannot fall through the opening in the top of the dashboard.
  3. Disconnect the sun sensor connector from the ATC harness.
  4. Examine the wiring from the sensor to the connector, and examine the connector for any signs of damage.
  5. Measure the resistance between the sun sensor connector terminals.

Is there any sign of damage in the wiring or connector or does the resistance equal the value specified?

0 ohms

Go to Step 2

Go to Step 3

2

Repair the damaged wiring on the connector, or replace the sun sensor as required.

Is the repair complete?

--

System OK

--

3

  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage between the 2 sun sensor connector terminals on the ATC harness.

Is the voltage less than the specified value?

4 V

Go to Step 7

Go to Step 4

4

Inspect the terminals on the sun sensor connector.

Is any problem found with the connector?

--

Go to Step 5

Go to Step 6

5

Repair the connector terminals or replace the sun sensor to ATC as required.

Is the repair complete?

--

System OK

--

6

  1. Reconnect the sun sensor to the ATC harness.
  2. Turn ON the ignition, with the engine OFF.
  3. Observe the temperature display area.

Does this display indicate the continuing presence of a code 5 condition?

--

Go to Step 9

System OK

7

  1. Pull the ATC from the instrument panel, leaving the wiring harness connected.
  2. Measure the voltage between terminals A13 and B10 by backprobing the connectors.

Is the voltage less than the specified value?

4 V

Go to Step 9

Go to Step 8

8

  1. Trace the wiring from controller terminals A13 and B10 to the sun sensor connector terminals on the ATC harness connectors.
  2. Repair any open or high resistance found in the wiring on connector terminals.

Is the repair complete?

--

System OK

--

9

Replace the ATC controller. Refer to Heater and Air Conditioning Control Replacement .

Is the repair complete?

--

System OK

--