Hummer H1 (2006+). Manual - part 59

OBD-80

On-Board Diagnostics

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Conditions for Clearing the MIL/DTC

• The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic

runs and does not fail.

• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related

diagnostic.

• Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

• The MAF Sensor parameter should increase from 24-50 g/s at idle to 320 g/s or more at the 2-3 shift during a wide-open

throttle (WOT) acceleration. If not, inspect for a restriction in the induction system or the exhaust system.

• If the condition is intermittent, refer to Intermittent Conditions and Inducing Intermittent Fault Conditions in Wiring Sys-

tems.

Step

Action

Value(s)

Yes

NOTE: Before clearing DTC(s) use the scan tool “Capture info”
to record Freeze Frame and Failure Records for reference, as data
will be lost when “Clear Info” function is used

Was the “On-Board Diagnostic (OBD) System Check” per-
formed?

Go to step 2.

Go to OBD Sys-

tem Check.

Start the engine.

Does the engine have fuel knock/combustion noise?

Go to Step 5

Go to Step 3

Allow the engine to idle.

Observe the MAF Sensor parameter with a scan tool.

Is the MAF Sensor parameter less than the specified value?

0.42 V

Go to Step 6

Go to Step 4

Observe the Freeze Frame/Failure Records for this DTC.

Turn OFF the ignition for 30 seconds.

Start the engine.

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 6

Go to Diagnos-

tic Aids

With the engine running, disconnect the mass air flow (MAF)/in-
take air temperature (IAT) sensor.

Does the engine have fuel knock/combustion noise?

Go to Step 12

Go to Step 15

Observe the MAF Sensor parameter with a scan tool.

Move the harness and the connector of the MAF/IAT sensor.

Does the movement of the harness or the connector affect the
MAF Sensor parameter?

Go to Step 19

Go to Step 7

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On-Board Diagnostics OBD-81

5745804

Turn OFF the ignition.

Inspect for air leaks in the following components:

• The air induction system and the turbocharger system

• The MAF sensor O-ring seal

• The boost pressure sensor seal

Inspect for the following conditions:

• An obstructed intake air duct or a dirty air filter element

• Any debris that is blocking the air sensing filaments of the

MAF sensor

• Contamination on the air sensing filaments of the MAF

sensor

• Water intrusion in the air induction system

• A MAF sensor that is installed backwards

• A restricted exhaust system

Did you find and correct the condition?

Go to Step 22

Go to Step 8

Inspect the fuse in the ignition voltage circuit 239 (PK) of the
MAF sensor.

Is the fuse open?

Go to Step 11

Go to Step 9

Turn ON the ignition, with the engine OFF.

Measure the battery voltage with a DVOM.

Disconnect the harness connector of the MAF/IAT sensor.

Connect a test lamp between the ignition voltage circuit 239
(PK) of the MAF sensor and a good ground.

Connect the DVOM to the probe of the test lamp and a good
ground.

Is the voltage within 1.5 volts of the specified value?

B+

Go to Step 10

Go to Step 17

Connect a 3-amp fused jumper wire between the ignition
voltage circuit 239 (PK) of the MAF sensor and the signal
circuit 654 (DB) of the MAF sensor.

Observe the MAF Sensor parameter with a scan tool.

Is the MAF Sensor parameter more than the specified value?

445 g/s

Go to Step 15

Go to Step 13

NOTE: The ignition voltage circuit 239 of the MAF sensor is
spliced to other components of the vehicle.

Test the MAF sensor ignition voltage circuit 239 (PK) for the fol-
lowing conditions:

• A short to ground

• Any shorted component on the spliced circuit

Did you complete the action?

Go to Step 22

Step

Action

Value(s)

Yes

OBD-82

On-Board Diagnostics

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Turn OFF the ignition.

Disconnect the engine control module (ECM).

Test the MAF sensor ignition voltage circuit 239 (PK) for the
following conditions:

• A short to the MAF sensor low reference circuit 251 (BK)

• A short to the IAT sensor low reference circuit 250 (BK)

Did you find and correct the condition?

Go to Step 22

Go to Step 16

Turn OFF the ignition.

Disconnect the fused jumper wire.

Disconnect the ECM.

Test the MAF sensor signal circuit 654 (DB) for the follow-
ing conditions:

• A high resistance or an open

• A short to ground

• A short to the IAT sensor low reference circuit

• A short to the MAF sensor low reference circuit

Did you find and correct the condition?

Go to Step 22

Go to Step 14

Measure the resistance from the signal circuit 654 (DB) of the
MAF sensor to all the other circuits at all of the ECM connectors
with a DVOM.

Is the resistance less than the specified value?

' ohms

Go to Step 18

Go to Step 16

Test for shorted terminals and for an intermittent and for a poor
connection at the MAF/IAT sensor.

Did you find and correct the condition?

Go to Step 22

Go to Step 20

Test for shorted terminals and for an intermittent and for a poor
connection at the ECM.

Did you find and correct the condition?

Go to Step 22

Go to Step 21

Repair the high resistance or the open in the MAF sensor ignition
voltage circuit 239 (PK).

Did you complete the repair?

Go to Step 22

Repair the circuits that are shorted together.

Did you complete the repair?

Go to Step 22

Repair the harness or the connections as necessary.

Did you complete the repair?

Go to Step 22

Replace the faulty MAF/IAT sensor.

Did you complete the replacement?

Go to Step 22

Replace the faulty ECM.

Did you complete the replacement?

Go to Step 22

Step

Action

Value(s)

Yes

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On-Board Diagnostics OBD-83

5745804

Clear the DTCs with a scan tool.

Turn OFF the ignition for 30 seconds.

Start the engine.

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 23

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

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