Hummer H1 (2002+). Manual - part 120

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 Brake System  7-39

®

05745159

4-13

Left rear

 wheel 

speed sensor 
open circuit.

18 and 35

500-2000 

W

Check electrical resistance of affected sensor and 
wiring at ECU connector and at harness plugs. 
Repair wiring or replace sensor as necessary.

4-14

Left front

 

wheel speed 
sensor open cir-
cuit.

15 and 32

500-2000 

W

Check electrical resistance of affected sensor and 
wiring at ECU connector and at harness plugs. 
Repair wiring or replace sensor as necessary.

4-15

Right rear

 

wheel speed 
sensor open cir-
cuit.

16 and 33

500-2000 

W

Check electrical resistance of affected sensor and 
wiring at ECU connector and at harness plugs. 
Repair wiring or replace sensor as necessary.

5-0

Short circuit to 
battery between 
ECU and right 
front inlet

 

valve solenoid 
or wiring.

6 and 27

0 volts

5.0-7.5 

W

Check voltages at wiring harness including con-
nectors. Check electrical resistance of affected 
valve wiring to ground at ECU connector and at 
modulator assembly plug. Repair wiring or 
replace as necessary.

5-1

Short circuit to 
battery between 
ECU and right 
front outlet

 

valve solenoid 
or wiring.

7 and 27

0 volts

3.0-5.0 

W

Check voltages at wiring harness including con-
nectors. Check electrical resistance of affected 
valve wiring to ground at ECU connector and at 
modulator assembly plug. Repair wiring or 
replace as necessary.

5-2

Short circuit to 
battery between 
ECU and left 
front inlet

 

valve solenoid 
or wiring.

23 and 27

0 volts

5.0-7.5 

W

Check voltages at wiring harness including con-
nectors. Check electrical resistance of affected 
valve wiring to ground at ECU connector and at 
modulator assembly plug. Repair wiring or 
replace as necessary.

5-3

Short circuit to 
battery between 
ECU and left 
front outlet

 

valve solenoid 
or wiring.

24 and 27

0 volts

3.0-5.0 

W

Check voltages at wiring harness including con-
nectors. Check electrical resistance of affected 
valve wiring to ground at ECU connector and at 
modulator assembly plug. Repair wiring or 
replace as necessary.

5-4

Short circuit to 
battery between 
ECU and right 
rear inlet

 valve 

solenoid or wir-
ing.

4 and 27

0 volts

5.0-7.5 

W

Check voltages at wiring harness including con-
nectors. Check electrical resistance of affected 
valve wiring to ground at ECU connector and at 
modulator assembly plug. Repair wiring or 
replace as necessary.

 Fault Code List

 Ignition key “OFF” to test system (except where noted)

Fault Code

Problem Area 

Test Pin 

Locations

Values

Check/Repair

7-40

Brake System

_____________________________________________________________

®

5-5

Short circuit to 
battery between 
ECU and right 
rear outlet

 

valve solenoid 
or wiring.

5 and 27

0 volts

3.0-5.0 

W

Check voltages at wiring harness including con-
nectors. Check electrical resistance of affected 
valve wiring to ground at ECU connector and at 
modulator assembly plug. Repair wiring or 
replace as necessary.

5-6

Short circuit to 
battery between 
ECU and left 
rear inlet

 valve 

solenoid or wir-
ing.

21 and 27

0 volts

5.0-7.5 

W

Check voltages at wiring harness including con-
nectors. Check electrical resistance of affected 
valve wiring to ground at ECU connector and at 
modulator assembly plug. Repair wiring or 
replace as necessary.

5-7

Short circuit to 
battery between 
ECU and left 
rear outlet

 

valve solenoid 
or wiring.

22 and 27

0 volts

3.0-5.0 

W

Check voltages at wiring harness including con-
nectors. Check electrical resistance of affected 
valve wiring to ground at ECU connector and at 
modulator assembly plug. Repair wiring or 
replace as necessary.

5-8

Short circuit to 
battery + 
between ECU 
and RCP relay 
1.

11 and 27

0 volts

Check wiring harness between ECU and relay and 
pump ground connections. Repair wiring as nec-
essary.

5-9

Short circuit to 
battery + 
between ECU 
and RCP relay 
2.

12 and 27

0 volts

Check wiring harness between ECU and relay and 
pump ground connections. Repair wiring as nec-
essary.

5-12

Right front

 

wheel speed 
signal is erratic.

17 and 34

Greater than 0.9 

volts AC at one 

tire revolution 

per second.

Check for damaged tone wheel, incorrect sensor 
adjustment, excessive tone wheel runnout 
(> .041"), excessive geared hub input bearing play 
and tire size mismatch. Repair or replace as neces-
sary.

5-13

Left rear

 wheel 

speed signal is 
erratic.

18 and 35

Greater than 0.9 

volts AC at one 

tire revolution 

per second.

Check for damaged tone wheel, incorrect sensor 
adjustment, excessive tone wheel runnout 
(> .041"), excessive geared hub input bearing play 
and tire size mismatch. Repair or replace as neces-
sary.

5-14

Left front

 

wheel speed 
signal is erratic.

15 and 32

Greater than 0.9 

volts AC at one 

tire revolution 

per second.

Check for damaged tone wheel, incorrect sensor 
adjustment, excessive tone wheel runnout 
(> .041"), excessive geared hub input bearing play 
and tire size mismatch. Repair or replace as neces-
sary.

 Fault Code List

 Ignition key “OFF” to test system (except where noted)

Fault Code

Problem Area 

Test Pin 

Locations

Values

Check/Repair

____________________________________________________________

 Brake System  7-41

®

05745159

5-15

Right rear

 

wheel speed 
signal is erratic.

16 and 33

Greater than 0.9 

volts AC at one 

tire revolution 

per second

Check for damaged tone wheel, incorrect sensor 
adjustment, excessive tone wheel runnout 
(> .041"), excessive geared hub input bearing play 
and tire size mismatch. Repair or replace as neces-
sary.

6-0

Short circuit 
between two 
solenoid valve 
leads of right 
front inlet 

sole-

noid valve.

6 and 4, 5, 7, 

21, 22, 23, 24

5.0-7.5 

W

Check electrical resistance of affected valves and 
wiring at ECU connector and at modulator assem-
bly plug. Repair or replace wiring as necessary 
and replace modulator if short is internal.
Note: Fault code for both affected valves will 
be stored in memory.

6-1

Short circuit 
between two 
solenoid valve 
leads of right 
front outlet 
solenoid valve.

7 and 4, 5, 6, 

21, 22, 23, 24

3.0-5.0 

W

Check electrical resistance of affected valves and 
wiring at ECU connector and at modulator assem-
bly plug. Repair or replace wiring as necessary 
and replace modulator if short is internal.
Note: Fault code for both affected valves will 
be stored in memory.

6-2

Short circuit 
between two 
solenoid valve 
leads of left 
front inlet 

sole-

noid valve.

23 and 4, 5, 6, 

7, 21, 22, 24

5.0-7.5 

W

Check electrical resistance of affected valves and 
wiring at ECU connector and at modulator assem-
bly plug. Repair or replace wiring as necessary 
and replace modulator if short is internal.
Note: Fault code for both affected valves will 
be stored in memory.

6-3

Short circuit 
between two 
solenoid valve 
leads of right 
front outlet 
solenoid valve.

24 and 4, 5, 6, 

7, 21, 22, 23

3.0-5.0 

W

Check electrical resistance of affected valves and 
wiring at ECU connector and at modulator assem-
bly plug. Repair or replace wiring as necessary 
and replace modulator if short is internal.
Note: Fault code for both affected valves will 
be stored in memory.

6-4

Short circuit 
between two 
solenoid valve 
leads of right 
rear inlet 

sole-

noid valve.

4 and 5, 6, 7, 

21, 22, 23, 24

5.0-7.5 

W

Check electrical resistance of affected valves and 
wiring at ECU connector and at modulator assem-
bly plug. Repair or replace wiring as necessary 
and replace modulator if short is internal.
Note: Fault code for both affected valves will 
be stored in memory.

6-5

Short circuit 
between two 
solenoid valve 
leads of right 
rear outlet 
solenoid valve.

5 and 4, 6, 7, 

21, 22, 23, 24

3.0-5.0 

W

Check electrical resistance of affected valves and 
wiring at ECU connector and at modulator assem-
bly plug. Repair or replace wiring as necessary 
and replace modulator if short is internal.
Note: Fault code for both affected valves will 
be stored in memory.

 Fault Code List

 Ignition key “OFF” to test system (except where noted)

Fault Code

Problem Area 

Test Pin 

Locations

Values

Check/Repair

7-42

Brake System

_____________________________________________________________

®

6-6

Short circuit 
between two 
solenoid valve 
leads of left 
rear inlet 

sole-

noid valve.

21 and 4, 5, 6, 

7, 22, 23, 24

5.0-7.5 

W

Check electrical resistance of affected valves and 
wiring at ECU connector and at modulator assem-
bly plug. Repair or replace wiring as necessary 
and replace modulator if short is internal.
Note: Fault code for both affected valves will 
be stored in memory.

6-7

Short circuit 
between two 
solenoid valve 
leads of left 
rear outlet 
solenoid valve.

22 and 4, 5, 6, 

7, 21, 23, 24

3.0-5.0 

W

Check electrical resistance of affected valves and 
wiring at ECU connector and at modulator assem-
bly plug. Repair or replace wiring as necessary 
and replace modulator if short is internal.
Note: Fault code for both affected valves will 
be stored in memory.

6-8

Short circuit 
between sole-
noid valve and 
RCP relay 1.

11 and 4, 5, 6, 

7, 21, 22, 23, 24

Open circuit

Check wiring harness at ECU connector to pump 
relay. Repair or replace as necessary.

6-9

Short circuit 
between sole-
noid valve and 
RCP relay 2.

12 and 4, 5, 6, 

7, 21, 22, 23, 24

Open circuit

Check wiring harness at ECU connector to pump 
relay. Repair or replace as necessary.

6-12

Right front

 

wheel speed 
signal missing.

17 and 34

Greater than 0.9 

volts AC at one 

tire revolution 

per second.

Check for damaged tone wheel, incorrect sensor 
adjustment, excessive tone wheel runnout 
(> .041"), excessive geared hub input bearing play 
and tire size mismatch. Repair or replace as neces-
sary.

6-13

Left rear

 wheel 

speed signal 
missing.

18 and 35

Greater than 0.9 

volts AC at one 

tire revolution 

per second.

Check for damaged tone wheel, incorrect sensor 
adjustment, excessive tone wheel runnout 
(> .041"), excessive geared hub input bearing play 
and tire size mismatch. Repair or replace as neces-
sary.

6-14

Left front

 

wheel speed 
signal missing.

15 and 32

Greater than 0.9 

volts AC at one 

tire revolution 

per second.

Check for damaged tone wheel, incorrect sensor 
adjustment, excessive tone wheel runnout 
(> .041"), excessive geared hub input bearing play 
and tire size mismatch. Repair or replace as neces-
sary.

6-15

Right rear

 

wheel speed 
signal missing.

16 and 33

Greater than 0.9 

volts AC at one 

tire revolution 

per second.

Check for damaged tone wheel, incorrect sensor 
adjustment, excessive tone wheel runnout 
(> .041"), excessive geared hub input bearing play 
and tire size mismatch. Repair or replace as neces-
sary.

 Fault Code List

 Ignition key “OFF” to test system (except where noted)

Fault Code

Problem Area 

Test Pin 

Locations

Values

Check/Repair