GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The automatic level control (ALC) sensor provides a signal voltage between 0.3-4.7 volts to its internal module. This signal voltage represents the wheel's position relative to the body. The ALC module is internal to the ALC sensor, and no external circuits are involved.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0625 Left Rear Position Sensor Circuit

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description .

DTC Symptom

DTC Symptom Descriptor

08

Signal Invalid

Conditions for Running the DTC

At power-up and continuous when ignition is activated

Conditions for Setting the DTC

The ALC control module senses a suspension sensor voltage below 0.3 volt or above 4.7 volts.

Action Taken When the DTC Sets

    • ALC functionality is suspended.
    • SERVICE AIR SUSPENSION message is displayed.

Conditions for Clearing the DTC

The DTC will clear when the condition for setting the DTC is removed.

Diagnostic Aids

This DTC is set for a high or low signal to the ALC control module from the position sensor. The ALC module is internal to the ALC sensor, and no external circuits are involved.

Step

Action

Values

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, with the engine OFF.
  2. With a scan tool, observe the Suspension Position Sensor Signal parameter in the data list for the ALC control module.

Is the Suspension Position Sensor Signal parameter within the specified range?

0.3-4.7 V

Go to Diagnostic Aids

Go to Step 3

3

Inspect for poor connections at the harness connector of the automatic level control (ALC) 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

Replace the ALC sensor. Refer to Automatic Level Control Sensor Replacement .

Did you complete the replacement?

--

Go to Step 5

--

5

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC.

Does DTC C0625 reset?

--

Go to Step 2

System OK