GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The automatic level control sensor monitors the exhaust valve on time when the vehicle is lowering and is limited to 255 seconds.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC 033 Exhaust Valve Excessive On Time

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 has been on for 255 seconds and the automatic level control sensor did not detect the calibrated downward movement.

Action Taken When the DTC Sets

The automatic level control sensor disables the leveling functions.

Conditions for Clearing the DTC

    • The conditions that caused the DTC to set have been removed.
    • The ignition switch has been cycled from OFF to ON.

Diagnostic Aids

An air line or exhaust valve blockage in the system will cause this DTC to set.

Test Description

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

  1. This step tests for something mechanical that is not allowing the vehicle to lower.

  2. This step verifies the automatic level control sensor connector to have a good connection.

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. Check all air lines and exhaust valves for airflow blockage.
  2. Check both rear shock absorbers for binding.

Did you find and correct the condition?

Go to Step 5

Go to Step 3

3

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 5

Go to Step 4

4

Important: System untested codes will continue to flash until a 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 5

--

5

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