GM Service Manual Online
For 1990-2009 cars only

Object Number: 520696  Size: MF
Automatic Level Control Suspension Components
Automatic Level Control w/F45
Handling ESD Sensitive Parts Notice
Power and Grounding Connector End Views Fuse Blocks and Ignition Switch
Body Control System Connector End Views
G401

Circuit Description

The automatic level control adjusts the vehicle suspension ride height. The Rim determines the height of the vehicle based on the voltage from the automatic level control sensor. The RIM grounds the compressor relay and the exhaust control solenoid to raise and lower the vehicle in order to keep the vehicle level.

Conditions for Running the DTC

    • The RIM is powered up.
    • DTC's B1328 and B1327 are not stored.

Conditions for Setting the DTC

The compressor relay output is found to be shorted to battery for 10 seconds.

Action Taken When the DTC Sets

The automatic level control will be inoperative.

Conditions for Clearing the MIL/DTC

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

Diagnostic Aids

    • Inspect all wiring harnesses carefully for chaff's and proper routing.
    • This circuit is monitored during every functional operation of the compressor relay output and every 3.3 milliseconds when output is active. If a compressor relay fault is detected, the RIM retries the output every 15 seconds to try to recover form the fault.

Test Description

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

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

  2. Tests for voltage at the coil side of the level control compressor relay. The ELC fuse supplies power to the coil side of the level control compressor relay.

  3. Verifies that the RIM is providing ground to the level control compressor relay.

  4. Tests if ground is constantly being applied to the level control compressor relay.

  5. Tests for a short to voltage.

Step

Action

Value(s)

Yes

No

1

Did you perform the Automatic Level Control Diagnostic System Check?

--

Go to Step 2

Go to Automatic Level Control Diagnostic System Check

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the level control compressor relay ON and OFF.

Does the level control compressor relay turn ON and OFF with each command?

--

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the level control compressor relay .
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the coil side feed circuit of the level control compressor relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 4

Go to Step 10

4

  1. Connect a test lamp between the control circuit of the level control relay and the coil side feed circuit of the level control compressor relay.
  2. With a scan tool, command the level control compressor relay ON and OFF .

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

--

Go to Step 8

Go to Step 5

5

Does the test lamp remain illuminated with each command?

--

Go to Step 7

Go to Step 6

6

Test the control circuit of the level control compressor relay for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 9

7

Test the control circuit of the level control compressor relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 9

8

Inspect for poor connections at the level control compressor relay . 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 13

Go to Step 11

9

Inspect for poor connections at the harness connector of 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 13

Go to Step 12

10

Repair the coil side feed circuit of the level control compressor relay . Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 13

--

11

Replace the level control compressor relay

Did you complete the replacement?

--

Go to Step 13

--

12

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

Did you complete the replacement?

--

Go to Step 13

--

13

  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.

Does the DTC reset?

--

Go to Step 2

System OK