Hummer H2. Manual - part 2209

2: This step checks the air suspension sensor - LR data parameter.  

3: This step tests for the proper operation of the circuit in the high voltage range.  

4: This step tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper 
opens upon performing this test, the signal circuit has a short to voltage.  

5: This step tests for a short to ground in the 5-volt reference circuit.  

7: This step tests the 5-volt reference circuit for the air suspension sensor - LR.  

DTC C0626 

Step

Action

Values

Yes

No

Schematic Reference: Suspension Controls Schematics

1

Did you perform the Air Suspension System 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, observe the Left Height Sensor 

parameter in the data list for the air suspension 
module.  

Is the Left Height Sensor parameter within the specified 
range?

0.3-4.7 

V

Go to 

Diagnostic 

Aids

Go to Step 3

3

1. Turn OFF the ignition.  

2. Disconnect the air suspension sensor - LR.  

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

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

parameter.  

Is the Left 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-LR 
and the low reference circuit of the air suspension 
sensor - LR.  

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

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

parameter.  

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

0.3 V

Go to Step 5

Go to Step 9

1. Turn OFF the ignition.  

 

2004 Hummer H2 

2004 SUSPENSION Air Suspension - Hummer H2

  

5

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 - LR.  

Is the Left 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-LR 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 - LR 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 - LR 
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 

15

Go to Step 12

9

Test the signal circuit of the air suspension sensor - LR 
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 - LR for one of the following conditions: 

z

A high resistance  

z

An open  

 

-

 

2004 Hummer H2 

2004 SUSPENSION Air Suspension - Hummer H2

  

DTC C0631 

Circuit Description 

The Air Suspension Sensor provides a signal voltage between 0.3 and 4.7 volts to the Air Suspension Module. 
This signal voltage represents the wheel's position relative to the body. The Air Suspension Module provides a 
5 volt reference and a low reference to the sensor. 

Conditions for Running the DTC 

At power-up and continuous when ignition is activated.

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 - LR. 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 - LR. 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 
the trim height procedure.  

Did you complete the replacement?

IMPORTANT:

Always perform the check trim height procedure after 
air suspension module 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

  

Conditions for Setting the DTC 

Air Suspension Module senses a suspension sensor voltage below 0.3 volts or above 4.7 volts. 

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 for a high or low signal to the Air Suspension Module from the Air Suspension Sensor-RR. 

Test Description 

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

2: Checks the Air Suspension Sensor - RR data parameter.  

3: Tests for the proper operation of the circuit in the high voltage range.  

4: Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens 
upon performing this test, the signal circuit has a short to voltage.  

5: Tests for a short to ground in the 5 volt reference circuit.  

7: Test the 5 volt reference circuit for the Air Suspension Sensor - RR.  

DTC C0631 

Step

Action

Values

Yes

No

Schematic Reference: Suspension Controls Schematics

1

Did you perform the Air Suspension System 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, observe the Right Height Sensor 

parameter in the data list for the Air Suspension 
Module.  

Is the Right Height Sensor parameter within the 
specified range?

0.3-4.7 

V

Go to 

Diagnostic 

Aids

Go to Step 3

1. Turn OFF the ignition.  

2. Disconnect the Air Suspension Sensor-RR.  

 

2004 Hummer H2 

2004 SUSPENSION Air Suspension - Hummer H2