GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2004 🢒 Rendezvous - AWD 🢒 Suspension 🢒 Automatic Level Control 🢒 DTC 021

Circuit Description

The height sensor monitors the compressor relay coil control circuity for a short to ground.

Conditions for Running the DTC

Ignition On.

Conditions for Setting the DTC

This DTC is set when the height sensor detects the compressor relay coil control circuit is shorted to ground.

Action Taken When the DTC Sets
    • The height sensor disables the compressor.
    • Lowering functions shall continue.
    • The height sensor disables inflator functions.

Conditions for Clearing the DTC

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

The ignition has transitioned from off to on.

Diagnostic Aids

A short to ground in the compressor relay coil circuit will set this DTC.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Tests for voltage at the coil side of the accessory inflator solenoid. The ELC relay fuse supplies power to the coil side of the accessory inflator solenoid.

    2.

  2. Verifies that the height sensor is providing ground to the accessory inflator solenoid.

    3.

  3. Tests if ground is constantly being applied to the accessory inflator solenoid.

    4.

  4. Verifies that the sensor is self tested after replacement.

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. Turn ON the ignition.
  2. Disconnect the accessory inflator solenoid.
  3. Probe the battery positive voltage circuit of the accessory inflator solenoid 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

  1. Connect a test lamp between the control circuit of the accessory inflator solenoid and the battery positive voltage circuit of the accessory inflator solenoid.
  2. With the accessory inflator switch, command the accessory inflator solenoid ON and OFF .

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

Go to Step 5

Go to Step 4

4

Test the control circuit of the accessory inflator solenoid for a short to voltage, ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 6

5

Inspect for poor connections at the accessory inflator solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

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 height sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 9

7

Repair the battery positive voltage circuit of the accessory inflator solenoid. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 10

--

8

Replace the accessory inflator solenoid. Refer to Inflator Solenoid Replacement

Did you complete the replacement?

Go to Step 10

--

9

Important: System untested code will continue to flash until self test has been completed after sensor replacement .

Replace the height 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