GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2005 🢒 Terraza Ext. 🢒 DTC 🢒 DTC 031

Circuit Description

The automatic level control sensor monitors the exhaust valve control circuity for a short to ground.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC 031 Exhaust Valve Circuit Short to Ground

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

This DTC is set when the automatic level control sensor detects the exhaust valve control circuit is shorted to ground.

Action Taken When the DTC Sets

The automatic level control sensor disables leveling functions.

Conditions for Clearing the DTC

The conditions that caused the DTC to set have been removed.

Diagnostic Aids

A short to ground in the exhaust valve control circuit will set this DTC.

Test Description

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

  1. This step tests for voltage at the coil side of the exhaust valve. The ELC fuse supplies power to the coil side of the exhaust valve.

    2.

  2. This step verifies that the automatic level control sensor is providing ground to the exhaust valve.

    3.

  3. This step tests if ground is constantly being applied to the exhaust valve.

    4.

  4. This step verifies that the automatic level control sensor is self tested after replacement.

Step

Action

Yes

No

Schematic Reference: Automatic Level Control Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn ON the ignition.
  2. Disconnect the exhaust valve.
  3. Probe the battery positive voltage circuit of the exhaust valve with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 3

Go to Step 7

3

Connect a test lamp between the control circuit of the exhaust valve and the battery positive voltage circuit of the exhaust valve.

Does the test lamp illuminate?

Go to Step 4

Go to Step 5

4

Test the control circuit of the exhaust valve for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 6

5

Inspect for poor connections at the exhaust valve. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 8

6

Inspect for poor connections at the harness connector of the automatic level control sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 9

7

Repair the battery positive voltage circuit of the exhaust valve. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 10

--

8

Replace the exhaust valve. Refer to Air Compressor Replacement .

Did you complete the replacement?

Go to Step 10

--

9

Important: System untested codes will continue to flash until self test has been completed after automatic level control sensor replacement .

Replace the automatic level control sensor. Refer to Automatic Level Control Sensor Replacement .

Did you complete the replacement?

Go to Step 10

--

10

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