Hummer H1 (2006+). Manual — part 57

OBD-72

On-Board Diagnostics

_______________________________________________

8

1.Turn OFF the ignition.

2.Verify the FRP regulator harness connector is disconnected.

3.Turn ON the ignition, with the engine OFF.

4.Probe the control circuit 511(YL) of the FRP regulator with a test
light connected to battery voltage.

Does the test lamp illuminate?

Go to Step 15

Go to Step 9

9

1.Disconnect the ECM C75.

2.Turn ON the ignition, with the engine OFF.

3.Measure the voltage from the FRP regulator control circuit 511 (YL)
to a good ground with a DVOM.

Does the voltage measure the specified value?

0 Volts

Go to Step 18

Go to Step 13

10

1.Turn OFF the ignition.

2.Disconnect the ECM connector C76.

3.Turn ON the ignition, with the engine OFF.

4.Probe the ignition 1, voltage circuit of the harness connector with a
test light that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 11

Go to Step 12

11

1.

Test for an open in the FRP supply circuit 510 (PP/WH) between
the ECM and the FRP regulator.

2.

If a condition is found, repair as necessary.

Did you find and correct the condition?

Go to Step 21

Go to Step 19

12

Repair the open in the ignition 1 voltage circuit to the ECM.

Did you complete the repair?

Go to Step 21

13

Repair the short to voltage in the control circuit between the ECM and
the FRP regulator.

Did you complete the repair?

Go to Step 21

14

Test for a short to ground in the control circuit between the ECM and
the FRP regulator.

Did you find and correct the condition?

Go to Step 21

Go to Step 20

15

Inspect the fuel pressure regulator connector for corrosion, pushed out
pins and correct pin tension.

Did you find and correct the condition?

Go to Step 21

Go to Step 16

16

1.

Test for an intermittent and for a poor connection at the FRP regu-
lator.

2.

Repair the wiring, as necessary.

Did you find and correct the condition?

Go to Step 21

Go to Step 17

17

Replace the faulty FRP regulator.

Did you complete the replacement?

Go to Step 21

18

Test for an open in the control circuit 511 (YL) between the ECM C75
pin 51 and the FRP regulator pin 2.

Did you find and correct the condition?

Go to Step 21

Go to Step 19

Step

Action

Value(s)

Yes

No

______________________________________________

On-Board Diagnostics OBD-73

5745804

19

1.

Inspect the ECM connector for corrosion, pushed out pins and
correct pin tension.

2.

Connect the ECM and the sensor.

3.

Key on, engine off.

4.

Clear the DTCs.

5.

Perform the On-Board Diagnostic (OBD) Self-Test.

Did you find and correct the condition?

Go to Step 21

Go to Step 20

20

Replace the faulty ECM.

Did you complete the replacement?

Go to Step 21

21

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 21

22

1.

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

Go to the

applicable

DTC table.

System OK.

Step

Action

Value(s)

Yes

No

OBD-74

On-Board Diagnostics

_______________________________________________

DTC P0101 Mass Air Flow (MAF) Sensor Performance (Figure OBD-23)

Figure OBD-23: Mass Air Flow (MAF) Sensor Circuit

Circuit Description

The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The engine control mod-
ule (ECM) uses the MAF sensor voltage signal to provide the correct fuel delivery for a reduction in emissions. The ECM uses the
MAF sensor signal to control fuel delivery until a calibrated amount of engine air flow is attained. The MAF sensor has an ignition
1 voltage circuit, a signal circuit and a low reference circuit. The MAF sensor produces an output voltage based on the inlet air flow
through the air induction system. This output voltage will display on the scan tool as a voltage parameter and as a grams per second
(g/s) parameter. The ECM will calculate a predicted MAF value. The ECM compares the actual MAF sensor voltage signal to the
predicted MAF value. This comparison will determine if the signal is stuck, or is too low or too high for a given operating condi-
tion. If the ECM detects that the actual MAF sensor voltage signal is not within a predetermined range of the calculated MAF
value, DTC P0101 sets.

Conditions for Setting the DTC

The ECM detects that the MAF sensor voltage signal is not within a predetermined range of the calculated MAF value for more
than 12 seconds.

Action Taken When the DTC Sets

• The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diag-

nostic runs and fails.

• The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the

control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecu-
tive ignition cycle, the control module records the operating conditions at the time of the failure. The control module
writes the operating conditions to the Freeze Frame and updates the Failure Records.

______________________________________________

On-Board Diagnostics OBD-75

5745804

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.

• Use a scan tool in order to clear the MIL and the DTC.

Diagnostic Aids

• Any unmetered air that enters the engine downstream of the MAF sensor may cause this DTC to set.

• A short between the signal circuit of the MAF sensor and the signal circuit of the intake air temperature (IAT) sensor will

skew the MAF sensor higher than normal at idle and less than normal at higher air flows.

• A malfunctioning MAF sensor can cause excessive engine emissions.

• The MAF display 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 vehicle condition is intermittent, refer to Inducing Intermittent Fault Conditions and Intermittent Conditions.

Step

Action

Value(s)

Yes

No

1

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.

2

Is DTC P0405 set?

Go to DTC

P0405 before

diagnosing this

code

Go to step 3.

3

1.

Observe the Freeze Frame/Failure Records for this DTC.

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 4

Go to Diagnos-

tic Aids

4

1.

Turn OFF the ignition.

2.

Turn ON the ignition, with the engine OFF.

3.

Observe the MAF Sensor parameter with a scan tool.

Is the MAF Sensor parameter more than the specified value?

0.30 Volts

Go to Step 7

Go to Step 5