Hummer H1 (2002+). Manual — part 234

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Electrical System 12-157

®

05745159

ANTENNA SYSTEM TEST

CHART #7

STEP

ACTION

VALUE(S)

YES

NO

1

Disconnect negative battery cable.
Disconnect antenna lead-in cable at the
radio receiver.
With a DVOM, measure resistance
between the coax (outer conductor) con-
nector and the negative battery cable.

NOTE: To avoid misdiagnosis be sure
to zero the meter before taking measure-
ments.

Is resistance value greater than.15 ohms?

> .15 ohms

Check the base of the

antenna for a good connec-

tion to body ground.

Check the coaxial cable

interconnects for a poor
connection or corrosion.

Check the ground connec-

tion from the battery nega-

tive cable to the body.

Repair the antenna ground

circuit as necessary.

Go to step 2.

2

Grasp the antenna mast.
While observing the DVOM, wiggle the
antenna and the lead-in cable ground
strap. Does the meter indicate intermit-
tent continuity?

Check the lead-in cable
ground strap for a good

connection to body ground.

Check the coaxial cable
interconnects for a poor

connection or corrosion.

Check the ground connec-

tion from the battery nega-

tive cable to the body.

Repair the antenna ground

circuit as necessary.

Go to step 3.

3

With a DVOM, measure the resistance
between the radio coax lead-in connector
(center conductor) and the antenna mast.

NOTE: To avoid misdiagnosis be sure
to zero the meter before taking measure-
ments.

Does the measured resistance equal ap-
proximately the value listed?

Less than

3.5 ohms

Go to step 4.

Check the coaxial cable

interconnects for a poor con-

nection or corrosion.

Repair/replace the antenna

coaxial circuit as necessary.

4

While observing the DVOM, wiggle the
antenna. Does the meter indicate inter-
mittent continuity?

Check the coaxial cable

interconnects for a poor
connection or corrosion.

Repair/replace the antenna

coaxial circuit as necessary.

See troubleshooting hints

for noise and poor reception.

4-1-00

12-158

Electrical System

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®

REAR SEAT AUDIO (RSA) DOES NOT OPERATE

CHART #8

STEP

ACTION

VALUE(S)

YES

NO

1

With ignition on, check for voltage at
C59 pin A8 (CKT 819 BK). Is voltage
present?

+12v

Go to step 2.

Check/repair open circuit

between C59 pin A8 and

C56 pin 4.

2

With ignition in the “RUN” position and
the radio “ON”, check for voltage at C59
pin B5 (CKT 842 OR). Is voltage present?

+12v

Go to step 3.

Check/repair open circuit

between C59 pin B5 and

C57 pin 19.

3

Check for continuity between C56 pin 8
(CKT 59 BK) and ground G4. Is there
continuity?

< 0.2

Ω

.

Go to step 4.

Repair circuit 59 BK

between C56 and ground

point G4.

4

Check for continuity between C56 pin 8
and C59 pin 6. Is there continuity?

< 0.2

Ω

.

Go to step 5.

Repair circuit 59 BK

between C56 and C59.

5

With ignition in the “RUN” position and
the RSA on, back probe C59 pin A5 (CKT
843 GY) and check for specified voltage.
Is the specified voltage present?

+ 5v

Go to step 6.

Replace RSA unit.

6

With ignition on and RSA on, check for
voltage at C57 pin 22 (CKT 843 GY).
Is the specified voltage present?

+ 5v

Go to step 7.

Check/repair open circuit

between C59 pin A5 and

C57 pin 22.

7

Check for an open circuit between C56
pin 15 and C59 pin A4 (CKT 820 DG).
Is there continuity?

< 0.2

Ω

.

Go to step 8.

Check/repair open circuit

between C59 pin A4 and

C56 pin 15.

8

Check for an open circuit between C56
pin 16 and C59 pin A3 (CKT 821 BK).
Is there continuity?

< 0.2

Ω

.

Go to step 9.

Check/repair open circuit

between C59 pin A3 and

C56 pin 16.

9

Check for an open circuit between C56
pin 9 and C59 pin A2 (CKT 818 PP).
Is there continuity?

< 0.2

Ω

.

Go to step 10.

Check/repair open circuit

between C59 pin A2 and

C56 pin 9.

10

Check for an open circuit between C56
pin 10 and C59 pin A1 (CTK 819 BK).
Is there continuity?

< 0.2

Ω

.

Go to step 1.

Check/repair open circuit

between C59 pin A1 and

C56 pin 10.

4-1-00

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Electrical System 12-159

®

05745159

CONNECTOR LEGEND

NOTE: Connector gender is determined by the terminals.

76 WAY BULKHEAD

LOCATION: LEFT SIDE FIREWALL

PIN

CKT

COLOR

CIRCUIT DESCRIPTION

1

400

LG

Ignition Feed +

2

739

PP

Left heated windshield power +

3

740

YL

Right heated windshield power +

4

43

DB

Trailer Brake activation

5

962

BR

Trailer lights

6

33

WH

neutral safety switch feed

7

37E

YL

start relay feed

8

37D

YL

Ignition switch feed

9

786

RD

Fuel selector valve control

10

537

OR

Battery

C1 MALE

9-S12-048

PIN 1

PIN 12

PIN 13

PIN 26

PIN 27

PIN 38

PIN 50

PIN 64

PIN 76

PIN39

PIN 51

PIN 65

C1 FEMALE

9-S12-047

CAV 1

CAV 13

CAV 27

CAV 39

CAV 51

CAV 65

CAV 12

CAV 26

CAV 38

CAV 50

CAV 64

CAV 76

4-1-00

12-160

Electrical System

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®

11

787

GY

Fuel pump + to selector valve

12

37

RD

Ignition relay feed

13

688

RD

Rear window defrost feed

14

723

YL

APP 3 5volt reference

15

724

DG

APP 3 signal

16

17

PP

+ FROM DIMMER MODULE

17

718

DB

APP 1 signal

18

353

YL

Speedometer signal

19

607

TN

ABS module diagnostic line

20

717

WH

APP 1 5volt reference

21

961

PP

TT4 lamp activation

22

720

TN

APP 2 5volt reference

23

640

OR

IGN+ CTIS warning circuits

24

92

GY

CTIS rear inflate solenoid activation

25

714

DB

Check throttle lamp activation

26

37

RD

Battery feed to interior accessories

27

338

DB

Wait lamp activation

28

658

BR

Check engine lamp activation

29

151

GY

Cruise control ON/OFF signal

30

31

TN

Oil pressure signal

31

22

RD

Brake switch signal – rest

32

721

LB

APP 2 sensor signal

33

580

BR

Not Used for 99 and 2000

34

606

OR

ABS diagnostic line

35

29

PK

Fuel gauge signal

36

39

DG

Engine temperature signal

37

153

LG

Cruise resume/accelerate signal

38

42

BR

Low brake fluid lamp activation

39

198

TN

A/C request

40

810

PP

TCC brake switch signal

41

2

LG

Right front turn signal

42

152

DB

Cruise set/coast signal

43

298

BR

Backup light switch feed

44

722

PP

APP 2 ground

45

327

YL

Water-in-fuel lamp activation

46

80

WH

Underhood lamp power

PIN

CKT

COLOR

CIRCUIT DESCRIPTION

4-1-00