Hummer H2. Manual - part 2210

3

3. Turn ON the ignition, with the engine OFF.  

4. With a scan tool, observe the Right Height Sensor 

parameter.  

Is the Right Height Sensor parameter more than the 
specified value?

0.3 V

Go to Step 4

Go to Step 8

4

1. Turn OFF the ignition.  

2. Connect a 3-ampere fused jumper wire between 

the signal circuit of the Air Suspension Sensor-RR 
and the low reference circuit of the Air 
Suspension Sensor - RR.  

3. Turn ON the ignition, with the engine OFF.  

4. With a scan tool, observe the Right Height Sensor 

parameter.  

Is the Right Height Sensor parameter less than the 
specified value?

0.3 V

Go to Step 5

Go to Step 9

5

1. Turn OFF the ignition.  

2. Disconnect the fused jumper wire.  

3. Turn ON the ignition, with the engine OFF.  

4. Test the 5 volt reference circuit voltage of the Air 

Suspension Sensor - RR.  

Is the Right Height Sensor 5 volt reference voltage 
greater than the specified value?

4.7 V

Go to Step 7

Go to Step 6

6

Test the 5 volt reference circuit of the Air Suspension 
Sensor-RR for a short to ground. Refer to Circuit 
Testing and to Wiring Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 

15

Go to Step 12

7

Test the 5 volt reference circuit of the Air Suspension 
Sensor - RR for one of the following conditions: 

z

A short to voltage  

z

A high resistance  

z

An open  

 
Refer to Circuit Testing and to Wiring Repairs in 
Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 

15

Go to Step 11

8

Test the signal circuit of the Air Suspension Sensor - RR 
for a short to voltage. Refer to Circuit Testing and to 
Wiring Repairs in Wiring Systems. 

-

Go to Step 

 

2004 Hummer H2 

2004 SUSPENSION Air Suspension - Hummer H2

  

Did you find and correct the condition?

15

Go to Step 12

9

Test the signal circuit of the Air Suspension Sensor - RR 
for one of the following conditions: 

z

A short to voltage  

z

A high resistance  

z

An open  

 
Refer to Circuit Testing and to Wiring Repairs in 
Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 

15

Go to Step 10

10

Test the low reference circuit of the Air Suspension 
Sensor - RR for one of the following conditions: 

z

A high resistance  

z

An open  

 
Refer to Circuit Testing and to Wiring Repairs in 
Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 

15

Go to Step 12

11

Inspect for poor connections at the harness connector of 
the Air Suspension Sensor - RR. Refer to Testing for 
Intermittent Conditions and Poor Connections and to 
Wiring Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 

15

Go to Step 13

12

Inspect for poor connections at the harness connector of 
the Air Suspension Module. Refer to Testing for 
Intermittent Conditions and Poor Connections and to 
Wiring Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 

15

Go to Step 14

13

Replace the Air Suspension Sensor - RR. Refer to Air 
Spring Leveling Sensor Replacement . 
Did you complete the replacement?

-

Go to Step 

15

-

14

1. Replace the Air Suspension Module. Refer to 

Module Assembly Electronic Suspension 
Control Replacement .  

2. Perform the Trim height calibration procedure for 

the Air Suspension Module if necessary after 
Check trim height procedure.  

IMPORTANT:

Always perform the check trim height procedure after 
Air Suspension Module replacement.

-

-

 

2004 Hummer H2 

2004 SUSPENSION Air Suspension - Hummer H2

  

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. 

Conditions for Running the DTC 

Ignition 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 

z

Air Suspension functionality is suspended.  

z

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. 

2: During the Air Suspension exhaust valve operation, listen for an audible click. Command the ON and 
the OFF states. Repeat the commands as necessary.  

3: Verifies that the Air Suspension Module is providing voltage to the Air Suspension Exhaust Valve.  

4: Tests for an open in the ground circuit to the Air Suspension Exhaust Valve.  

Did you complete the replacement?

Go to Step 

15

15

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

 

2004 Hummer H2 

2004 SUSPENSION Air Suspension - Hummer H2

  

5: Tests for constant voltage to the Air Suspension Exhaust Valve.  

DTC C0660 

Step

Action

Yes

No

Schematic Reference: Suspension Controls Schematics

1

Did you perform the Air Suspension Diagnostic System 
Check?

Go to Step 2

Go to Diagnostic 

System Check - Air 

Suspension

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. 

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 to 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 to Wiring Repairs in 
Wiring Systems. 
Did you find and correct the condition?

Go to Step 

13

Go to Step 9

Inspect for poor connections at the exhaust valve. Refer to 

 

2004 Hummer H2 

2004 SUSPENSION Air Suspension - Hummer H2