GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 HUMMER 🢒 2005 🢒 H2 🢒 DTC 🢒 DTC C0660

Circuit Description

The air suspension exhaust valve is controlled by the air suspension module. The air suspension module provides a switched path to voltage whenever exhaust valve activity is required. The air suspension module monitors the exhaust valve circuity to determine if the voltage level agrees with the command state.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0660 Level Control Exhaust Valve Circuit

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

Air suspension module senses exhaust valve voltage does not agree with command state.

Action Taken When the DTC Sets
    • Air suspension 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 when the exhaust valve circuitry is shorted to ground, voltage and open.

Test Description

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

  1. During the air suspension exhaust valve operation, listen for an audible click. Command the ON and the OFF states. Repeat the commands as necessary.

    2.

  2. Verifies that the air suspension module is providing voltage to the air suspension exhaust valve.

    3.

  3. Tests for an open in the ground circuit to the air suspension exhaust valve.

    4.

  4. Tests for constant voltage to the air suspension exhaust valve.

Step

Action

Yes

No

Schematic Reference: Suspension Controls Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

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

Does the exhaust 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 valve.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp to ground.

    5. Probe the control circuit of the exhaust valve with a test lamp that is connected to ground.

  5. With a scan tool, command the exhaust valve ON and OFF.

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

Go to Step 4

Go to Step 5

4

  1. Connect a test lamp between the control circuit of the exhaust valve and the ground circuit of the exhaust valve.
  2. With a scan tool, command the exhaust valve ON and OFF.

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

Go to Step 8

Go to Step 10

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 exhaust valve for a short to ground or an open. 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 exhaust valve 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

8

Inspect for poor connections at the exhaust valve. 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 13

Go to Step 11

9

Inspect for poor connections at the harness connector of the Air Suspension Module. 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 13

Go to Step 12

10

Repair the ground circuit of the exhaust valve. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 13

--

11

Replace the air suspension exhaust valve. Refer to Compressor Assembly Automatic Level Control Air Replacement .

Did you complete the replacement?

Go to Step 13

--

12
  1. Replace the air suspension module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup and programming.
  2. Perform the trim height calibration procedure for the air suspension module if necessary after check trim height procedure.

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.

Does the DTC reset?

Go to Step 2

System OK