Hummer H1 (2006+). Manual - part 70

OBD-124

On-Board Diagnostics

_____________________________________________

    5

WARNING:   This System Uses High Voltage

NOTE: Failure to identify the correct cylinder will result in mis-
diagnosis. Use the J 35616-94 adapters to probe the fuel injection
control module (FICM) connector. 

1.

Turn OFF the ignition.

2.

Disconnect the FICM.

3.

Measure the resistance between the injector supply voltage 
circuit for cylinders 2, 3, 5, and 8 and a known good ground 
with a DVOM.

Does the DVOM display OL?

Go to Step 7

Go to Step 6

    6

Disconnect cylinders 2, 3, 5, and 8 harness connectors for each of
the fuel injectors one at a time, while monitoring the DVOM.

Does the DVOM display OL when any of the fuel injector har-
ness connectors are disconnected?

Go to Step 21

Go to Step 30

    7

NOTE:

• The DVOM and test leads must be calibrated to 0 ohms in 

order to prevent misdiagnosis. Use the DVOM to per-
form this test. Refer to the DVOM User Manual for 
calibration procedure. 

• The temperature of the engine and injectors should be the 

same as when the DTC set. 

• Use the J 35616-94 adapters to probe the FICM connector. 

Measure the resistance between the injector supply voltage cir-
cuit and the injector command circuits for cylinders 2, 3, 5, and 8
with a DVOM.

Does the DVOM display OL for all of the circuits?

Go to Step 31

Go to Step 8

    8

Does the DVOM display OL for any of the circuits?

Go to Step 22

Go to Step 9

    9

Does the DVOM display a resistance above the specified value
for any fuel injector circuit?

0.8 ohms

Go to Step 24

Go to Step 10

    10

Does the DVOM display a resistance below the specified value
for any fuel injector circuit?

0.3 ohms

Go to Step 25

Go to Step 11

    11

NOTE:  Use the J 35616-94 adapters to probe the FICM connec-
tor.

1.

Turn ON the ignition, with the engine OFF.Probe the injector 
supply voltage circuit for cylinders 2, 3, 5 and 8, with a 
DVOM connected to ground.

Does the DVOM display battery voltage?

Go to Step 12

Go to Step 33

    12

Disconnect cylinders 2, 3, 5, and 8 harness connectors for each of
the fuel injectors one at a time, while monitoring the DVOM.

Does the DVOM display the specified voltage when any of the
fuel injector harness connectors are disconnected?

0 Volts

Go to Step 28

Go to Step 27

Step

Action

Value(s)

Yes

No

_____________________________________________

 On-Board Diagnostics  OBD-125

5745804

    13

WARNING:  Refer to High Voltage Caution in Cautions
and Notices.

NOTE:

• Use the J 35616-94 adapters to probe the FICM connector. 

• Failure to identify the correct cylinder will result in misdi-

agnosis.

1.

Turn OFF the ignition.

2.

Disconnect the FICM.

3.

Measure the resistance between the injector supply voltage 
circuit for cylinders 1, 4, 6, and 7 and a known good ground 
with a DVOM.

Does the DVOM display OL?

Go to Step 15

Go to Step 14

    14

Disconnect cylinders 1, 4, 6, and 7 harness connectors for each of
the fuel injectors one at a time, while monitoring the DVOM.

Does the DVOM indicate OL when any of the fuel injector har-
ness connectors are disconnected?

Go to Step 21

Go to Step 30

    15

NOTE:

• Use the J 35616-94 adapters to probe the FICM connector. 

• The DVOM and test leads must be calibrated to 0 ohms in 

order to prevent misdiagnosis. Refer to the DVOM 
User Manual for calibration procedure. 

• The temperature of the engine and injectors should be the 

same as when the DTC set. 

Measure the resistance between the injector supply voltage cir-
cuit and the injector command circuits for cylinders 1, 4, 6 and 7
with a DVOM.

Does the DVOM display OL for all of the circuits?

Go to Step 31

Go to Step 16

    16

Does the DVOM display OL for any of the circuits?

Go to Step 22

Go to Step 17

    17

Does the DVOM display a resistance above the specified value
for any fuel injector circuit?

0.8 ohms

Go to Step 24

Go to Step 18

    18

Does the DVOM display a resistance below the specified value
for any fuel injector circuit?

0.3 ohms

Go to Step 25

Go to Step 19

    19

NOTE: Use the J 35616-94 adapters to probe the FICM connec-
tor.

1.

Turn ON the ignition, with the engine OFF.

2.

Probe the injector supply voltage circuit for cylinders 1, 4, 6 
and 7, with a DVOM connected to ground.

Does the DVOM display battery voltage?

Go to Step 20

Go to Step 33

Step

Action

Value(s)

Yes

No

OBD-126

On-Board Diagnostics

_____________________________________________

    20

Disconnect cylinders 1, 4, 6, and 7 harness connectors for each of
the fuel injectors one at a time, while monitoring the DVOM.

Does the DVOM display the specified voltage when any of the
fuel injector harness connectors are disconnected?

0 Volts

Go to Step 28

Go to Step 27

    21

Measure the resistance from the fuel injector command circuit to
ground at the FICM connector for the cylinder that caused the
DVOM to display OL.

Does the DVOM display continuity?

Go to Step 29

Go to Step 26

    22

1.

Disconnect the connector of the fuel injector that displayed 
OL.

2.

Test the command circuit of the fuel injector between the 
FICM and the injector connector, for the following condi-
tions:

• An open circuit 

• A poor connection 

Did you find and correct the condition?

Go to Step 35

Go to Step 23

    23

Test the injector voltage circuit of the fuel injector, between the
injector connector and the splice, for the following conditions:

• An open circuit 

• A poor connection 

Did you find and correct the condition?

Go to Step 35

Go to Step 26

    24

1.

Disconnect the injector connector for the circuit with high 
resistance.

2.

Test for the following conditions:

• Excessive resistance in the fuel injector circuits between 

the FICM and the injector connector 

• Poor connections at the injector connector of the fuel in-

jector

Did you find and correct the condition?

Go to Step 35

Go to Step 25

    25

Test for a short between the injector supply voltage circuit and
the fuel injector command circuit. 

Did you find and correct the condition?

Go to Step 35

Go to Step 26

    26

Test for an intermittent and for a poor connection at the harness
connector of the fuel injector. 

Did you find and correct the condition?

Go to Step 35

Go to Step 32

    27

Repair the short to voltage in the injector supply voltage circuit. 

Did you complete the repair?

Go to Step 35

    28

Repair the short to voltage in the fuel injector command circuit
that changed to 0 volts on the DVOM. 

Did you complete the repair?

Go to Step 35

    29

Repair the short to ground in the fuel injector command circuit. 

Did you complete the repair?

Go to Step 35

Step

Action

Value(s)

Yes

No

_____________________________________________

 On-Board Diagnostics  OBD-127

5745804

    30

Repair the short to ground in the injector supply voltage circuit. 

Did you complete the repair?

Go to Step 35

    31

Repair the open in the injector supply voltage circuit. 

Did you complete the repair?

Go to Step 35

    32

Replace the appropriate faulty fuel injector.

Did you complete the replacement?

Go to Step 35

    33

Test for an intermittent and for a poor connection at the harness
connector of the FICM. 

Did you find and correct the condition?

Go to Step 35

    34

Replace the faulty FICM. 

Did you complete the replacement?

Go to Step 35

    35

1.

Clear the DTCs with a scan tool.

2.

Turn OFF the ignition for 30 seconds.

3.

Start the engine.

4.

Operate the vehicle within the Conditions for Running the 
DTC. You may also operate the vehicle within the conditions 
that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2 

Go to Step 18 

   36

1.

Using the Scan Tool select “Capture Info,” Review Info.” Are 
any DTC’s displayed that have not been diagnosed?

Go to the appli-

cable DTC 

table.

System OK.

Step

Action

Value(s)

Yes

No