Hummer H1 (2002+). Manual - part 281

_____________________________________________________

PCM/Tech 1 Scan Tool 57

®

05745159

DTC P0223 - Accelerator Pedal Position (APP) Sensor 2 Circuit High Voltage

Step

Action

Value(s)

Yes

No

1

Important:

 Before clearing DTC(s) use the scan tool “Capture Info” to

record Freeze Frame and Failure Record for reference, as data will be lost
when “Clear Info” function is used.

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

—

Go to Step 2. Go to OBD Sys-

tem Check.

2

1. Ignition “ON”, engine “OFF”.
2. With the throttle closed, observe APP 2 display on the scan tool.

Is APP 2 greater than or equal to the specified value?

4.75v

Go to Step 4. Go to Step 3.

3

DTC is intermittent. If no additional DTCs are stored, refer to “Diagnostic
Aids”. If additional DTCs were stored, refer to those chart(s).

—

Go to the 

applicable 

DTC table.

Go to 

Diagnostic 

Aids.

4

1. Disconnect the APP sensor electrical connector.
2. Observe the APP 2 display on the Scan Tool.

Is APP 2 less than or equal to the specified value?

.25v

Go to Step 5. Go to Step 6.

5

Probe APP 2 sensor ground circuit at the APP sensor harness connector 
with a test light connected to B+.
Is the test light “ON”?

—

Go to Step 7.

Go to Step 8.

6

1. Check for a short to voltage on the APP 2 sensor signal circuit.
2. If the APP 2 sensor signal circuit is shorted, repair it as necessary.
Was the APP 2 sensor signal circuit shorted?

—

Go to Step 11. Go to Step 10.

7

Check for poor electrical connections at the APP sensor and replace termi-
nals if necessary.
Did any terminals require replacement?

—

Go to Step 11. Go to Step 10.

8

1. Check for an open sensor ground circuit.
2. If a problem is found, repair as necessary.

Was APP 2 sensor ground circuit open?

—

Go to Step 11. Go to Step 10.

9

Replace the APP module.

Is Action complete?

—

Go to Step 11.

—

10

Replace the faulty PCM. Notice: If the PCM is faulty, the new PCM must 
be programmed. Go to PCM replacement and programming procedures.
Is the action complete?

—

Go to Step 10.

—

11

1. Using the Scan Tool, select “DTC”, “Clear Info”.
2. Start engine and idle at normal operating temperature.

3. Select “DTC”, “Specific”, then enter the DTC number which was set.

4. Operate vehicle within the conditions for setting this DTC as specified in

the supporting text.

Does the Scan Tool indicate that this diagnostic Ran and Passed?

—

Go to Step 12.

Go to Step 2.

12

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

—

Go to the 

applicable 

DTC table

System OK

58

PCM/Tech 1 Scan Tool

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®

DTC P0225 Accelerator Pedal Position (APP) 
Sensor 3 Circuit

Circuit Description

The Accelerator Pedal Position (APP) module provides a volt-
age signal that changes relative to accelerator position. There
are three sensors located within the APP module that are scaled
differently. This is a type C DTC.

Conditions for Setting the DTC

• Reference voltage on APP 3 less than 4.8 volts.

• Condition met for 2 seconds.

Action Taken When the DTC Sets

If DTC P0225 is present, the PCM will turn “ON” the “Service
Throttle Soon” lamp and limit power.

Conditions for Clearing the MIL/DTC

• A History DTC will clear when forty consecutive 

warm-up cycles that the diagnostic does not fail (coolant 
temperature has risen 5°C (40°F) from start up coolant 
temperature and engine coolant temperature exceeds 
71°C (160°F) that same ignition cycle).

• Use of a Scan Tool

Diagnostic Aids

All 5 volt reference circuits must be checked for proper refer-
ence voltage. Volt meter accuracy is important.

Test Description

Number(s) below refer to the number(s) on the diagnostic ta-
ble.

2. This step will check all 5 volt reference circuits.

FUSE 5C
10AMP
INTERIOR

FUSE 3A
10 AMP
EXTERIOR

ON/
OFF

SET
COAST

RESUME
ACCEL

HOT IN RUN
AND START

HOT IN RUN
AND START

A

29

42

37

C1

C29-A11

C29-B11

C27-D10

C28-D14

C28-C2

C27-D12

C27-D3

C27-D4

C27-D6

C29-B2

C29-B1

C27-C5

C29-A12

C5-D3

C5-A4

A

B

154 TN

151 GY

152 DB

153 LG

ON / OFF
SIGNAL

SET
COAST
SIGNAL

RESUME
ACCEL
SIGNAL

WASTEGATE
SOLENOID
CONTROL

5 VOLT
REFERENCE

APP 3
SIGNAL

GROUND

APP 1
SIGNAL

GROUND

GROUND

D

B

C

A

G

E

F

J

K

3

1

2

C1

22

20

14

15

60

32

53

17

44

720 TN

717 WH

723 YL

724 DG

725 GY

718 DB

719 BR

721 LB

722 PP

ACCELERATIOR
PEDAL POSITION
SENSOR

POWERTRAIN
CONTROL
MODULE
(PCM)

APP 2
SIGNAL

9-S12-055

B

C

D

295 BR

YL

GRN

RD

_____________________________________________________

PCM/Tech 1 Scan Tool 59

®

05745159

DTC P0225 - Accelerator Pedal Position (APP) Sensor 3 Circuit

Step

Action

Value(s)

Yes

No

1

Important:

 Before clearing DTC(s) use the scan tool “Capture Info” to

record Freeze Frame and Failure Record for reference, as data will be lost
when “Clear Info” function is used.

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

—

Go to Step 2. Go to OBD Sys-

tem Check.

2

1. Disconnect the APP sensor electrical connector.
2. Ignition “ON”, engine “OFF”.

3. With J–39200 connected to ground, check all APP 5 volt reference cir-

cuits at APP harness.

Is voltage less than specified value?

4.8v

Go to Step 4. Go to Step 3.

3

DTC is intermittent. If no additional DTCs are stored, refer to “Diagnostic
Aids”. If additional DTCs were stored, refer to those chart(s).

—

Go to the 

applicable 

DTC table.

Go to 

Diagnostic 

Aids.

4

1. Ignition “OFF”.
2. Disconnect the PCM and check the 5 volt reference circuit for a short to

ground.

3. If the 5 volt reference circuit is shorted to ground, repair as necessary

Was the 5 volt reference circuit shorted to ground?

.25v

Go to Step 6. Go to Step 5.

5

Replace the faulty PCM. Notice: If the PCM is faulty, the new PCM must 
be programmed. Go to PCM replacement and programming procedures.
Is the action complete?

—

Go to Step 6.

—

6

1. Using the Scan Tool, select “DTC”, “Clear Info”.
2. Start engine and idle at normal operating temperature.

3. Select “DTC”, “Specific”, then enter the DTC number which was set.

4. Operate vehicle within the conditions for setting this DTC as specified in

the supporting text.

Does the Scan Tool indicate that this diagnostic Ran and Passed?

—

Go to Step 7.

Go to Step 2.

7

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

—

Go to the 

applicable 

DTC table

System OK

60

PCM/Tech 1 Scan Tool

_____________________________________________________

®

DTC P0226 Accelerator Pedal Position (APP) 
Sensor 3 Circuit Performance

Circuit Description

The Accelerator Pedal Position (APP) module provides a volt-
age signal that changes relative to accelerator position. There
are three sensors located within the APP module that are scaled
differently. This is a type C DTC.

Conditions for Setting the DTC

• Ignition voltage is greater than 6.4 volts.

• Engine speed greater than 300 rpm.

• The difference between APP 3 and APP 1 is greater than 

.23 volts (PCM compares pre-scaled voltage (internal to 
PCM)).

• The difference between APP 3 and APP 2 is greater than 

.50 volts (PCM compares pre-scaled voltage (internal to 
PCM)).

• No in range faults for APP 1 or APP 2 (PCM checks for 

high and low voltage faults).

• Conditions met for 2 seconds.

Action Taken When the DTC Sets

• The input from APP 3 sensor is ignored.

• A current and history DTC will set but it will not turn 

“ON” the “Service Throttle Soon” lamp.

• The throttle will operate normally as long as there is 

only one malfunction present. If there are two APP mal-
functions present, the PCM will then turn “ON” the 

“Service Throttle Soon” lamp and limit power. If a third 
APP malfunction is present, the “Service Throttle Soon” 
lamp will be “ON” and will only allow the engine to op-
erate at idle.

Conditions for Clearing the MIL/DTC

• A History DTC will clear when forty consecutive 

warm-up cycles that the diagnostic does not fail (coolant 
temperature has risen 5°C (40°F) from start up coolant 
temperature and engine coolant temperature exceeds 
71°C (160°F) that same ignition cycle).

• Use of a Scan Tool

Diagnostic Aids

A scan tool reads APP 3 position in volts and should read about
4.0 volts with throttle closed and ignition “ON” or at idle. Volt-
age should decrease at a steady rate as throttle is moved toward
Wide Open Throttle (WOT). Also, 90% pedal travel is accept-
able for correct APP operation. Scan APP 3 sensor while de-
pressing accelerator pedal with engine stopped and ignition
“ON”. Display should vary from about 4.0 volts when throttle
was closed to about 2.0 volts when throttle is held at Wide
Open Throttle (WOT) position.

Test Description

Number(s) below refer to the number(s) on the diagnostic ta-
ble.

2. This step determines if there is a good reference voltage.

FUSE 5C
10AMP
INTERIOR

FUSE 3A
10 AMP
EXTERIOR

ON/
OFF

SET
COAST

RESUME
ACCEL

HOT IN RUN
AND START

HOT IN RUN
AND START

A

29

42

37

C1

C29-A11

C29-B11

C27-D10

C28-D14

C28-C2

C27-D12

C27-D3

C27-D4

C27-D6

C29-B2

C29-B1

C27-C5

C29-A12

C5-D3

C5-A4

A

B

154 TN

151 GY

152 DB

153 LG

ON / OFF
SIGNAL

SET
COAST
SIGNAL

RESUME
ACCEL
SIGNAL

WASTEGATE
SOLENOID
CONTROL

5 VOLT
REFERENCE

APP 3
SIGNAL

GROUND

APP 1
SIGNAL

GROUND

GROUND

D

B

C

A

G

E

F

J

K

3

1

2

C1

22

20

14

15

60

32

53

17

44

720 TN

717 WH

723 YL

724 DG

725 GY

718 DB

719 BR

721 LB

722 PP

ACCELERATIOR
PEDAL POSITION
SENSOR

POWERTRAIN
CONTROL
MODULE
(PCM)

APP 2
SIGNAL

9-S12-055

B

C

D

295 BR

YL

GRN

RD