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Hummer H1 (2002+). Manual - part 122

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Brake System 7-47

05745159

Figure 7-51: 42 Pin Underbody Connector Male Half

Figure 7-52: 42 Pin Underbody Connector Female Half

PIN

CKT

COLOR

DESCRIPTION

996

Left front wheel speed sensor low signal

997

Left front wheel speed sensor high signal

999

Right front wheel speed sensor high signal

998

Right front wheel speed sensor low signal

994

Right rear wheel speed sensor low signal

995

Right rear wheel speed sensor high signal

992

Left rear wheel speed sensor low signal

993

Left rear wheel speed sensor high signal

9-S12-015

C2 MALE

PIN 34

PIN 28

PIN 22

PIN 16

PIN 10

PIN 1

PIN 42

PIN 33

PIN 27

PIN 21

PIN 15

PIN 9

9-S12-016

C2 FEMALE

CAV 42

CAV 33

CAV 27

CAV 21

CAV 15

CAV 9

CAV 34

CAV 28

CAV 22

CAV 16

CAV 10

CAV 1

7-48

Brake System

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ABS MODULATOR REPLACEMENT

Removal

WARNING: Batteries must be disconnected when the
brake hydraulic system is being serviced and bled. If the
ABS motor pump runs when air is in the hydraulic sys-
tem, air can get trapped behind the valves in the modu-
lator causing a spongy brake pedal.

Disconnect the batteries.

Remove the left front splash shield.

Remove the horn bracket and horns (Figure 7-53).

Figure 7-53: Brake Line And Wire Connections

Remove the thirteen-pin, the two-pin and the one-pin wire
connectors from the modulator assembly.

Remove the master cylinder brake hoses at the modulator
and cap off (note the position of the lines in the modulator
for installation).

Remove the four wheel brake lines from the modulator
and cap off (note the position of the lines in the modulator
for installation).

Remove the “P” clamp securing the oil cooler lines to the
modulator mounting bracket.

Remove the four bolts, washers and lock washers securing
the modulator bracket to the air lift bracket (Figure 7-54).

Figure 7-54: Modulator and Bracket Assembly-

Mounting

Remove the modulator, mounting bracket and shield from
the vehicle.

10. Remove the motor pump wire connector from the

modulator bracket and the two bolts securing the
modulator to the bracket.

Figure 7-55: Modulator Mounting

9-S07-011

2-PIN

PUMP

CONNECTOR

1 AND

13-PIN

CONNECTORS

9-S07-010

AIR
LIFT

BRACKET

9-S07-012

ALIGNMENT

PIN

MOUNTING

BRACKET

MODULATOR

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Brake System 7-49

05745159

11. Disengage the modulator alignment pin from the

mounting bracket and remove the modulator from the
mounting bracket.

12. Remove the brake line adapters, noting the position for

reinstallation

Installation

Install the brake line adapters in the same position as in the
original modulator. Torque the 12 mm threaded adapter to
11 lb-ft (15 N•m) and the 10 mm adapter to 9 lb-ft (12
N•m).

Place the modulator alignment pin in the hole in the
mounting bracket, install the two mount bolts and torque
to 5 lb-ft (7 N•m).

Connect the motor pump wire connector to the mounting
bracket and install the assembly on the left air lift bracket
with four bolts, washers and lock washers. Torque the
bolts to 28 lb-ft (38N•m).

Connect the four wheel brake lines in their respective
positions on the modulator and torque to 11 lb-ft (15
N•m).

Connect the master cylinder hoses in their respective
positions on the modulator and torque to 11 lb-ft (15
N•m).

Connect the thirteen-pin, the two-pin and the one-pin wire
connectors to the modulator assembly.

Install the horn bracket and horns.

Install the left front splash shield.

Bleed the complete brake system.

10. Connect the batteries.

SPEED SENSOR REPLACEMENT

NOTE:

The procedure for speed sensor replacement is basi-

cally the same for all four wheel ends.

WARNING: Connect speed sensors to the proper har-
ness connectors. Connecting speed sensors to incorrect
harness connectors can cause the ABS/TT4 to malfunc-
tion.

Removal

Rotate and pull the speed sensor head from the speed sen-
sor mounting bracket and retaining sleeve (Figure 7-56).

Remove and discard the speed sensor retaining sleeve.

Figure 7-56: Speed Sensor Removal

Remove the speed sensor connector from the retaining clip
near the top of the upper A-arm and disconnect the speed
sensor lead from the speed sensor harness (Figure 7-57).

Remove the capscrews and clips securing the speed sensor
lead to the A-arm and geared hub, and remove the sensor
from the vehicle.

Figure 7-57: Speed Sensor Connection

CLIP

SENSOR

CONNECTOR

9-S07-015

7-50

Brake System

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Installation

NOTE:

Left side speed sensor leads route across above the

halfshaft cv-joint. Care must be taken to ensure the lead does
not come in contact with the cv-joint.

Clean all grease, rust and debris from the speed sensor
cavity in the speed sensor mounting bracket.

Figure 7-58: Left Side Sensor Lead Routing

Install a new speed sensor retainer sleeve in the speed
sensor mounting bracket.

Lubricate the head of the speed sensor with chassis lube
and install in the speed sensor mounting bracket. Push the
speed sensor all the way in until it touches the tone wheel
on the CV joint.

Route the speed sensor lead away from the halfshaft and
secure with the clips and capscrews (do not kink the speed
sensor lead).

Connect the speed sensor connector to the speed sensor
harness connector and install into the connector retaining
clip.

TONE WHEEL REPLACEMENT

NOTE:

The tone wheel is pressed onto the outer CV joint of

the halfshaft and requires halfshaft replacement when servicing
the tone wheel. See section 9.

ABS ECU REPLACEMENT

Turn ignition switch “OFF”.

Remove the ECU enclosure hold-down bracket and lift the
top half of the ECU enclosure up and out of the pocket in
the windshield washer fluid reservoir.

Pull the ECU and ECU harness out of the lower half of the
ECU enclosure, depress the lock tabs on the 35 pin harness
connector and swing the connector around until the hook
on the end opposite of the lock tab disconnects from the
ECU.

Reverse the procedure for installation.

FUSE AND RELAY REPLACEMENT

The ABS TT4 system has three fuses located in the under-hood
fuse/relay center (Figure 7-59):

A 5 ampere ignition power fuse.

A 25 ampere battery power fuse.

A 40 ampere motor pump fuse.

The ABS TT4 system has four relays:

Valve relay.

Warning relay.

Pump relay 1.

Pump relay 2.

The valve relay and the warning relay are located in the under-
hood fuse/relay center (Figure 7-59). The valve and warning
relays are accessible after removal of the under-hood fuse/relay
center cover. The two pump relays are located forward of the
fuse-relay center and can be accessed after removing the ABS
ECU enclosure hold-down bracket.

Figure 7-59: ABS/TT4 Relay Locations.

P-CLAMP

SENSOR

LEAD

9-S07-013

VALVE

RELAY

PUMP

RELAY 1

PUMP

RELAY 2

WARNING

RELAY

40 AMP
MOTOR

PUMP

25 AMP

BATTERY

5 AMP

IGNITION

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