Hummer H1 (2006+). Manual - part 223

6-42

Wheels and Tires/Central Tire Inflation System (CTIS)

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Figure 6-50:   Quick-Disconnect Tab

Figure 6-51:   Pneumatic Diagram for Central Tire Inflation System 

02-OM4-001

VALVE

SPINDLE

NUT

QUICK

DISCONNECT

VALVE ASSEMBLY

AIR TUBE

ALUMINUM
LUG COVER

RETAINING

SCREWS

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 Wheels and Tires/Central Tire Inflation System (CTIS)  6-43

5745804

CTIS AIR LEAK TROUBLESHOOTING

This section contains troubleshooting information for locating and correcting air leaks within the Central Tire Inflation System.

WARNING:  The CTIS air system components are subject to high pressure. Always relieve the air pressure before
loosening or removing any of the air system component(s) by disconnecting the quick-disconnect valve assemblies
at each wheel end. Failure to follow this warning may result in serious personal injury.

CTIS Troubleshooting Checklist

1.

Fill all the tires to at least 40 psi (270 kPa) using the on-board compressor or a shop air source.

2.

Note the needle positions on the air gauge. If the needles are not even, line them up by inflating the lower pressure tires. Then
return the inflate/deflate switch to OFF.

NOTE: The tires are isolated from the rest of the system so that the areas between the compressor selector valve and geared hubs
and selector valve can be isolated and checked.

3.

Isolate each tire and wheel assembly by disconnecting each quick-disconnect valve.

4.

After the tires have been isolated, measure and record each tire’s air pressure.

5.

After a minimum of 10 minutes, check to see if the air gauge needles have moved.

NOTE: Leaks can be detected by using soapy water, but commercially available leak detection liquids such as “Gaz-Tec” work
best. Most leaks can be corrected by tightening the fittings. Replace the fittings or air lines only when necessary.

6.

Determine if the front, rear, or both air systems have leaked. If a leak is detected, concentrate on that area and follow the
appropriate troubleshooting chart.

• Geared Hubs, Seals, and Fittings - Chart 1

• Deflate Valve Area - Chart 2

• Under the Vehicle Air Leak - Chart 3

7.

After checking and repairing the leak points, place the selector switch in the BOTH position. 

8.

Note the gauge needle positions. Reposition or re-inflate to align the needles.

9.

Wait at least two minutes and check to see if the needles have moved. If movement is detected, concentrate on detecting the
leak point. Follow  Refer to Troubleshooting Chart 4 – Air Compressor Leak Test in this Section..

NOTE: If the tires were hot, air loss may be a result of the tires cooling down. If this is the case, all tires should lose about the same
amount of air.

10. Check the air pressure in each tire and compare it to the information taken earlier. Note any air pressure loss and concentrate

on that tire position. Refer to Troubleshooting Chart 5– Tire and Quick-Disconnect Valve in this Section..

If no air loss is detected, there may be a small leak which will require an overnight evaluation.

NOTE: Always complete the entire troubleshooting procedure to ensure that all potential leak points have been corrected.

Verification

After completing the troubleshooting procedure, verify the system by repeating the CTIS Troubleshooting checklist steps.

WARNING:  The CTIS air system components are subject to high pressure. Always relieve the air pressure before
loosening or removing air system component(s) by disconnecting quick-disconnect valve assemblies at each wheel
end. Failure to follow this procedure may result in serious personal injury.

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Wheels and Tires/Central Tire Inflation System (CTIS)

_______________

Inspect the steering arm cover,
connector, and tube for damage.
Use a soap and water solution or a
commercial leak detection product
around the connector and steering
arm cover.

Damage is found

Replace the con-
nector or tube.

Air is leaking around the con-
nector or tube end.

Tighten the connec-
tor, hose clamp or
tube fitting.

Remove the connector from the
tube and steering arm cover. In-
spect connector and tube fitting
for damage (frays, stripped
threads, cracks, or breaks).

Leak continues

Damage is found

Apply new thread sealant
and install connector to
steering arm cover and
tube fitting or tube.

Air is leaking around steering arm
cover.

Steering arm cover seal or exten-
sion may need replacement. Re-
move steering arm cover and
inspect the seal for damage (Figure
 6-74).

Damage is found

If air is in hub, re-

place seal.

Remove the vent line and deter-
mine if air is escaping. If so, steer-
ing arm cover seal is damaged.

Loose Component

Replace seal

if damaged

Replace part

if damaged

Troubleshooting Chart 1 – Geared Hubs, Seals and Fittings

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 Wheels and Tires/Central Tire Inflation System (CTIS)  6-45

5745804

Inspect the deflate valve and con-
nections for damage (Figure
 6-62). Use a soap and water solu-
tion to check for leaks.

Air is escaping from the
dust excluder or the seams
on the Deflate Valve (Fig-
ure  6-63).

Replace the
deflate valve.

Air is escaping from the
sides of the check valve.

Replace the
check valve.

Tighten all suspect connections. If this fails to seal
the air leak, take the connections apart, clean, apply
new sealant, and tighten.

Leaks

Troubleshooting Chart 2 – Deflate Valve Area

Follow the CTI lines under the vehi-
cle. Inspect for damage. Use a soap
and water or commercial leak detec-
tion solution to detect air leaks.

Tighten all suspect connectors. If this fails to stop the air leak, re-
move the suspect part (elbow, fitting or connector) and inspect
the threads for stripping. Clean, apply new pipe sealant, and in-
stall into the CTI system.

Troubleshooting Chart 3 – Under The Vehicle Air Leak

Check the relief valve to en-
sure air is not leaking from
the relief valve stem area.

Replace the
relief valve.

Air is
leaking

If air is leaking from a fitting, tee, elbow or
tube connection, tighten the part. If leak
persists, remove the CTI part, clean, apply
new sealant to the threads and install the
CTI part.

Air is
leaking

Troubleshooting Chart 4 – Air Compressor Leak Test

Inspect all fittings, tees, valves and
hoses connected to the compressor
(Figure  6-52). Use soap and water or
commercial leak detection product to
detect leaks.