Hummer H1 (2002+). Manual - part 204

 

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 Electrical System  12-43

 

 

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05745159

 

Figure 2-72:   Glow Plug Control Circuit Schematic

 

30

Use a scan tool to clear the DTC’s. Start the 
engine. Allow the engine to idle until the engine 
reaches normal operating temperature. Select the 
DTC and the specific DTC function. Enter the 
DTC number which was set. Operate the vehicle, 
with the Conditions for Setting this DTC, until 
the scan tool indicates the diagnostic Ran.
Does the scan tool indicate the diagnostic Passed?

Go to step 31.

Go to step 2.

31

Does the scan tool display any addition undiag-
nosed DTC’s?

Go to the appli-

cable DTC 

table.

System OK.

 

 Glow Plugs Inoperative (Cont’d)

 

Step

Action

Value

Yes

No

FUSE 3A
20 AMP
EXTERIOR

HOT IN RUN
AND START

GLOW PLUG
RELAY

IGN

POWER

FUSIBLE
LINK

W

AIT

WAIT TO START
LAMP CONTROL

C9-J

C9-A

C3-D1

C1-27

C28-C7

GLOW PLUGS RH

GLOW PLUG

RELAY

CONTROL

GLOWPLUG

FEEDBACK

SIGNAL

POWERTRAIN
CONTROL
MODULE
(PCM)

C27-D7

C27-C6

30 GY

466 YL

G1

#1

#3

#5

#7

BK

C5-A4

338 DB

C3-N7

RIGHT
BANK
OUTPUT

00-S12-011

B+

C5-C11

C5-B4

GLOW PLUGS LH

#2

#4

#6

#8

BATT +

LEFT

BANK

OUTPUT

RH STATUS

CENTER

5V

506 LB

239 PK

A

C

TO

STARTER

POS. STUD

B

B

C

D

A

D

C

B

A

D

FUSE 4B
5 AMP
INTERIOR
FUSE BOX

TO

IGNITION

SWITCH

 

4-1-00

 

12-44

Electrical System

 

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 Fuel Lift Pump Inoperative VIN Z  

 

Step

Action

Value(s)

Yes

No

 

1

Important: Before clearing the DTC’s use the scan 
tool Capture Info in order to record the Freeze 
Frame and the failure records for reference, as the 
data will be lost when the clear function is used.

Was the On-Board Diagnostic (OBD) System 
Check performed?

Go to step 2.

Go to Power-
train OBD sys-
tem check.

2

Turn the ignition OFF for 10 seconds. Turn the 
ignition ON. Does the fuel pump operate during 
the glow plug cycle?

System OK, 
problem may be 
intermittent.

Go to step 3.

3

Disconnect the fuel lift pump connector. Using a 
DVOM set to measure voltage, place the ground 
lead on a known good ground, and the positive 
lead on the grey wire (CKT787) at the fuel lift 
pump engine harness connector. Turn the ignition 
OFF for 10 seconds. Turn the ignition ON. Is volt-
age present?

12v

Go to step 4.

Go to step 5.

4

Place ground lead of DVOM on the black wire 
(CKT57) at the fuel lift pump engine harness con-
nection.With the positive lead still on the grey 
wire (CKT787) Turn the ignition OFF for 10 sec-
onds. Turn the ignition ON. Is voltage present?

12v

Replace fuel lift 
pump.

Go to step 5.

5

Reconnect the fuel lift pump, Disconnect the fuel 
lift pump relay. Using a DVOM set to measure 
voltage, place the ground lead on known good 
ground, and place the positive lead on the org wire 
(CKT537). Is voltage present?

12v

Go to step 6.

Repair open or 
short to ground 
in CKT537 
between fuel 
pump relay and 
fuse 2D.

6

Place the ground lead of the DVOM set to mea-
sure voltage on the black wire (CKT57). With the 
positive lead still on the org wire (CKT537). Is 
voltage present?

12v

Go to step 7.

Repair open or 
short to ground 
in CKT57 
between fuel 
pump relay and 
engine ground.

7

Using a DVOM set to measure voltage, place the 
ground lead on the black wire (CKT57)on the fuel 
lift pump relay connection. Place the positive lead 
on the dark green wire (CKT238). Turn the igni-
tion OFF for 10 seconds. Turn the ignition ON. Is 
voltage present?

12v

Replace the fuel 
lift pump relay.

Go to step 8.

8

Reconnect the fuel lift pump relay. Using the scan 
tool, command the fuel pump relay “on”. Does the 
pump run?

12v

Check for open 
in CKT787 
between the fuel 
lift pump relay 
and the PCM 
32pin xxxx con-
nector pin D5.

Go to step 9.

 

4-1-00

 

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 Electrical System  12-45

 

 

®

 

05745159

9

Disconnect fuel lift pump relay.Using a DVOM 
set to measure ohms, measure resistance between 
C27-D5, and the fuel lift pump relay dark green 
wire (CKT238). Does resistance exceed specifica-
tions?

<.2

 

Ω

 

Repair open or 
bad connection 
in CKT 238 
between PCM 
and fuel lift 
pump relay.

Go to step 10.

10

Using a DVOM set to measure ohms, measure 
continuity to ground between the dark green 
wire(CKT238) and engine ground. Is continuity 
present?

Repair short to 
ground in 
CKT238.

Go to step 11.

11

Replace PCM. Is repair complete?

Go to step 12.

12

Turn the ignition OFF for 10 seconds. Turn the 
ignition ON. Does the fuel pump operate during 
the glow plug cycle?

Repair com-
pleted.

Go to step 1.

 

 Fuel Lift Pump Inoperative VIN Z  (Cont’d)

 

Step

Action

Value(s)

Yes

No

4-1-00

 

12-46

Electrical System

 

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Figure 2-73:   Fuel Lift Pump Schematic

FUSE 2D
20A
INTERIOR

FUEL PUMP
RELAY
EXTERIOR
FUSE BOX

C1-10

G2

POWERTRAIN

CONTROL

MODULE

FUEL PUMP

RELAY CONTROL

FUEL LIFT
PUMP SIGNAL

TO FUEL

SELECTOR SWITCH

M

G2

FUEL
LIFT
PUMP

B

A

57 BK

787 GY

787 GY

787 GY

C27-D5

57 BK

C27-D8

238 DG

537 OR

9-S12-051

 

4-1-00