Hummer H1 (2006+). Manual - part 222

6-38

Wheels and Tires/Central Tire Inflation System (CTIS)

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CAUTION: The sleeve clamps must be positioned between 3/16” and 5/16” from the end of the sleeve and the bolt and nut torqued
to 30 lb-ft (41 N•m) (Figure 6-46).

Figure 6-44: Front Wheel Toe Adjustment Points

Verify that the steering wheel is centered. Move the steering wheel to the straight-ahead position if necessary.

Rear Wheel Toe Adjustment

Position both rear wheels on the alignment rack turntables.

Loosen the clamps on both radius rods(Figure 6-45).

Turn the adjusting sleeves until the toe measurement is within specifications.

Tighten the clamp nuts and verify the toe adjustment.

Figure 6-45: Rear Wheel Toe Adjustment Points

SLEEVE

CLAMP

ADJUSTING

SLEEVE

TIE ROD

SLEEVE

CLAMP

ADJUSTING

SLEEVE

CLAMP

RADIUS ROD

UPPER CONTROL ARM

CLAMP

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Wheels and Tires/Central Tire Inflation System (CTIS) 6-39

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Figure 6-46: Sleeve Clamp Position

STEERING STOP ADJUSTMENT

NOTE: Alignment equipment currently used in the automotive field should be used for steering stop adjustment procedure. This
procedure should be followed if alignment equipment is not available.

Removal

Loosen the jam nut and remove the bolt and the jam nut from the geared hub (Figure 6-47).

Remove the jam nut from the bolt.

Figure 6-47: Steering Stop Adjustment

Installation

Apply thread-locking compound to the bolt (Figure 6-48).

Thread the jam nut on the bolt.

Secure the bolt and jam nut to the geared hub. Tighten the bolt finger tight.

Adjustment

3/16”-5/16”

TORQUE TO

30 LB. FT.

RIM

TIE ROD

WHEEL

JAMNUT

GEARED HUB

STOP

CLAMP

6-40

Wheels and Tires/Central Tire Inflation System (CTIS)

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NOTE: Prior to adjustment, ensure the length of each tie rod is the same. If the tie rod lengths are not the same ± 1/8 in. (3 mm),
check the toe-in alignment setting.

Draw a reference chalk line 30 feet long. Mark this line A (Figure 6-48).

Position the vehicle so that center of left rear and left front tires are positioned directly on the reference line A.

Using a protractor, draw a reference line at 34 degrees from line A. Mark this line B.

Again, using a protractor, draw a reference line at 36 degrees from line A. Mark this line C.

Figure 6-48: Checking Alignment

Roll the vehicle forward until the center of the left front tire is over the intersection of lines A, B, and C.

Turn the steering wheel full left.

If the center line of the front and rear of the left front tire is over the area between lines B and C, no adjustment is necessary.

If the center line of the front and rear of the left front tire is not over the area between lines B and C, loosen the jam nut and
turn the bolt all the way in.

Turn the steering wheel until the center line of the front and rear of the left front tire is over the area between lines B and C.

10. Unscrew the bolt until the head makes contact with the wheel stop on the lower control arm (Figure 6-47).

11. Secure the bolt with the jam nut.

12. Check for clearance between the tie rod clamp and the rim.

13. Repeat the adjustment procedure for the opposite side.

CENTRAL TIRE INFLATION SYSTEM

The optional Central Tire Inflation System (CTIS) is unique to the HUMMER H1. The CTIS allows the driver to increase or de-
crease tire pressure based on terrain and climate conditions. The system can also be used to direct air to a tire that has a leak.

The CTIS controls are located on the instrument panel. An inflate/deflate switch determines if air is added to the tires or released
from the tires. When the tires are being inflated, an indicator light on the instrument panel illuminates. If the pressure in any of the
tires drops to 8 psi (55 kPa) or below, the low pressure indicator light will illuminate and an alarm will sound. If the tire pressure

LINE A

LEFT FRONT TIRE

LEFT

LINE C

LINE B

36°

34°

REAR

TIRE

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Wheels and Tires/Central Tire Inflation System (CTIS) 6-41

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ever exceeds 55 psi (379 kPa), a relief valve automatically relieves any excess pressure. The tire selector valve position determines
whether the pressure in the front, rear or all four tires will be adjusted. The air pressure gauge indicates the current pressure in the
tires. Refer to the short, white needle for front tire pressure and the longer, orange needle for the pressure in the rear tires. Tem-
perature rise and fall affects air pressure in a tire. As the vehicle is operated it is typical for the air pressure to rise 3-5 psi (21-34
kPa). As the wheels and tires cool down, the air pressure will drop. This is normal and such a drop in tire pressure does not indicate
any leaks in the system.

The CTIS consists of an electric air compressor that pumps air through a series of valves, tubes, and hoses to the front and/or rear
tires. Compressed air travels through the manifold where three electric valves connected in parallel direct the compressed air to the
front, rear or both tires. When deflation is selected, air is routed from the tires through the three electric valves and is exhausted
through the deflate valves (Figure 6-49).

Each wheel assembly has a manual quick-disconnect valve which can be used to prevent air flow to and from the tire, such as dur-
ing long-term storage or while changing a tire. If the vehicle will remain dormant for two weeks or more, it is a good practice to
disconnect the system at the wheels. These quick-disconnect valves are also used to restrict air flow to the operational tires when
the driver wants to direct air flow to a damaged tire. For example, if a tire has a small puncture and has a leak, the quick-discon-
nect valves on the operational tires can be disconnected, enabling compressed air to be directed exclusively to the leaking tire. This
may maintain enough tire pressure in the leaking tire to allow the driver to get the vehicle to an appropriate location for safe tire re-
pair or replacement (Figure 6-50).

Figure 6-49: Central Tire Inflation System (CTIS)

To disconnect the CTIS from the wheel assemblies, first turn inflate/deflate switch to the OFF position. Release the four quick-dis-
connect valve assemblies from all four spindles by depressing the quick-disconnect valve tabs attached to the valve spindle
nuts(Figure 6-50). When the tabs are depressed, the valve assemblies will spring away from the spindles about 1/2 inch (12.7 mm).
To reconnect the quick-disconnect valve assemblies, push the valve assemblies toward the spindles until they click into place.

CTIS TROUBLESHOOTING

The following pages contain troubleshooting information for locating and correcting mechanical, pneumatic, and electrical prob-
lems that may develop with the CTIS.

Electrical Troubleshooting

Symptoms are listed for system malfunctions, and procedures and corrections are diagramed to assist service technicians.

RADIAL TIRE

WHEEL

QUICK

DISCONNECT

SPINDLE

HALFSHAFT

AIR SEAL

FROM

FITTING

PASSAGE

COMPRESSOR

1-PIECE

RUN FLAT

BEAD LOCK

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