Hummer H1 (2002+). Manual - part 211

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 Electrical System  12-71

®

05745159

 Oil Pressure Gauge Inoperative

Step

Action

Value(s)

Yes

No

1

Is gauge maxed out?

Repair open or 

bad connection 

in CKT31 or 

gauge sending.

Go to step 2.

2

Using a DVOM set to measure voltage, check for 
voltage at the rear of the oil pressure gauge on the 
grey wire(CKT30) connect negative meter lead to 
ground on black wire(CKT59). With ignition on, 
is voltage present?

12v

Go to step 4.

Go to step 3.

3

Move the negative meter lead to a known good 
ground. Is voltage present?

12v

Repair open or 

bad connection 

in CKT59 

between oil 

pressure gauge 

and G4.

Repair open, 

bad connection 

or short in 

CKT30 between 

oil pressure 

gauge and fuse 

4B.

4

 Ignition on, remove the tan wire (CKT 31) from 
the oil pressure gauge. Does the gauge max out?

Go to step 5.

Replace the oil 

pressure gauge.

5

Reconnect signal wire to gauge. Disconnect sig-
nal wire(CKT31) at sending unit. With ignition on 
does gauge max out?

Replace send-

ing unit.

Repair short to 

ground in 

CKT31.

4-1-00

12-72

Electrical System

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®

 Fuel Gauge Inoperative

Step

Action

Value(s)

Yes

No 

1

Using a DVOM set to measure voltage, check for 
voltage at the rear of the fuel gauge on the grey 
wire(CKT30) connect negative meter lead to 
ground on black wire(CKT59). With ignition on, 
is voltage present?

12v

Go to step 3.

Go to step 2.

2

Move the negative meter lead to a known good 
ground. IS voltage present?

12v

Repair open or 

bad connection 

in CKT59 

between fuel 

gauge and G4.

Repair open, 

bad connection 

or short in 

CKT30 between 

fuel gauge and 

fuse 4B.

3

With the ignition on, ground the signal lead does 
the gauge go to Full?

Full

Go to step 4.

Replace gauge.

4

Disconnect fuel selector valve. Using a jumper 
wire, ground the pink wire(CKT29). With the 
ignition on does the fuel gauge go to full?

Full

Go to step 5.

Repair open or 

bad connection 

in CKT29 

between fuel 

gauge and fuel 
selector valve?

5

Determine fuel level in the main tank. Using a 
DVOM set to measure resistance, measure resis-
tance to ground on the blue wire(CKT673). Does 
resistance value correspond with fuel level in 
tank.

Empty=268

Ω

Half=124.4

Ω

Full=19.3

Ω

Go to step 6.

Go to step 7.

6

Determine fuel level in the auxiliary tank. Using a 
DVOM set to measure resistance, measure resis-
tance to ground on the yellow wire(CKT675). 
Does resistance value correspond with fuel level 
in tank.

Empty=268

Ω

Half=124.4

Ω

Full=19.3

Ω

Replace fuel 

selector valve.

Go to step 7.

7

Gain access to fuel level sending unit connectors. 
Using a DVOM set to measure resistance, check 
resistance through the sending unit. Does resis-
tance value correspond with the fuel level in the 
tank?

Empty=268

Ω

Half=124.4

Ω

Full=19.3

Ω

Repair open, 

bad connection 

or short in CKT 
673, 675, or 58.

Replace send-

ing unit.

4-1-00

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 Electrical System  12-73

®

05745159

 Engine Temperature Gauge Inoperative

Step

Action

Value(s)

Yes

No

1

Is gauge maxed out with ignition on?

Repair short to 

ground in CKT 

39 or faulty 

sending unit.

Go to step 2.

2

Using a DVOM set to measure voltage, check for 
voltage at the rear of the oil pressure gauge on the 
grey wire(CKT39) connect negative meter lead to 
ground on black wire(CKT59). With ignition on, 
is voltage present?

12v

Go to step 4.

Go to step 3.

3

Move the negative meter lead to a known good 
ground. Is voltage present?

12v

Repair open or 

bad connection 

in CKT59 

between oil 

pressure gauge 

and G4.

Repair open, 

bad connection 

or short in 

CKT30 between 

oil pressure 

gauge and fuse 

4B.

4

With the ignition on, momentarily ground the 
dark green wire(CKT30) at the rear of the gauge. 
Does the gauge go to maximum?

Go to step 5.

Replace the 

temperature 

gauge.

5

With the ignition on, momentarily ground the sig-
nal wire(CKT39) at the sending unit. Does the 
gauge go to maximum?

Replace the 

sending unit.

Repair open, or 

bad connection 

in CKT39 

between gauge 

and sending 

unit.

4-1-00

12-74

Electrical System

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Figure 2-93:   Gauges Schematic

FUSE
4B
5 AMP
INTERIOR
FUSE BOX

TO

DIMMER

SWITCH

TO IGNITION

VOLT

OIL

SPEEDO

TEMP

FUEL

G

I

L

I

G L

S

G L S

I

I

G L

S

I

G L

S

59 BK

30 GY

17 PP

G4

C3-N6

C3-N7

C3-L7

C1-30

C5-C10

G1

O I L

P R E S S U R E

S E N D E R

TO

IGN

SWITCH

31 TN

353 YL

C3-P9

C1-I8

39 DG

C3-P8

C1-36

C5-A1

29 PK

C3-P7

C1-35

C2-35

C26-B

ENGINE

TEMPERATURE

SENSOR

GAUGE

OUTPUT

FUEL

SELECTOR

VALVE

DIGITAL

RATIO

ADAPTER

(DRA)

SPEEDO

SIGNAL

SPEED SIGNAL

ENGINE

GROUND IGN+

679 LG

676 PP

570 BK

239 PK

8

9

9-S12-059.3

TO VEHICLE

SPEED SENSOR (VSS)

G2

C26-C

675 YL

A

AUX TANK
FUEL LEVEL
SENDING UNIT

MAIN TANK

FUEL LEVEL

SENDING UNIT

673 DB

58 BK

C26-A

B

C38-B

G1

G1

FUSE
3A
20 AMP
EXTERIOR
FUSE BOX

I S

TACHOMETER

G L

644 YL

C3-K9

C1-49

C5-B9

349 YL

TO CTIS
HARNESS

CRANKSHAFT

POSITION

SENSOR

TO PCM

349 YL

12

7

10

4-1-00