GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 2001 🢒 Aurora 🢒 Suspension 🢒 Automatic Level Control 🢒 DTC C0663

Circuit Description

The automatic level control (ALC) adjusts the vehicle suspension ride height. The RIM determines the height of the vehicle based on the voltage from the suspension position sensor. The RIM raises and lowers the vehicle in order to keep the vehicle level.

Conditions for Running the DTC
    • The RIM is powered up.
    • DTC B1327 is not stored.

Conditions for Setting the DTC

The exhaust solenoid control circuit is found to be shorted to battery .

Action Taken When the DTC Sets

The automatic level control will be inoperative.

Conditions for Clearing the DTC

The RIM does not detect a failure during the self test.

Diagnostic Aids
    • Inspect for the addition of aftermarket components.
    • Inspect all wiring harnesses carefully for chaffing and proper routing. Refer to Testing for Electrical Intermittents and Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • This circuit is monitored every 3 milliseconds. If the exhaust valve solenoid is found to shorted to battery for 10 milliseconds (100th of a second) the code will be stored as current.

Test Description

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

  1. Listen for an audible click when the solenoid operates. Command both the ON and OFF states. Repeat the commands as necessary.

    2.

  2. Tests the exhaust valve solenoid circuit for proper operation.

    3.

  3. Tests the control circuit for a short to voltage.

Step

Action

Yes

No

Schematic Reference: Automatic Level Control Schematics

1

Did you perform the Automatic Level Control Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Automatic Level Control

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the ALC exhaust solenoid valve ON and OFF.

Does the exhaust solenoid valve turn ON and OFF with each command?

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the exhaust solenoid valve harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the control circuit and the battery positive voltage circuit of the exhaust solenoid harness connector.
  5. With a scan tool, command the exhaust solenoid ON and OFF.

Does the test lamp turn ON and OFF with each command?

Go to Step 6

Go to Step 4

4

Does the test lamp remain OFF with each command?

Go to Step 5

Go to Step 7

5

Test the exhaust solenoid control circuit for a short to voltage. Refer to Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 7

6

Inspect for poor connections at the exhaust valve solenoid harness connector. 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 10

Go to Step 8

7

Inspect for poor connections at the RIM. 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 10

Go to Step 9

8

Replace the compressor head assembly. Refer to Automatic Level Control Air Compressor Head Replacement .

Did you complete the replacement?

Go to Step 10

--

9

Important: Perform the ALC relearn procedure.

Replace the RIM. Refer to Rear Integration Body Control Module Replacement .

Did you complete the replacement?

Go to Step 10

--

10
  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.

Did the DTC reset?

Go to Step 2

System OK