Hummer H2. Manual — part 1529

DTC P0120

Step

Action

Values

Yes

No

Schematic Reference:Engine Controls Schematics
Connector End View Reference:Engine Controls Component Views or Powertrain Control Module
(PCM) Connector End Views

1

Did you perform the Diagnostic System Check -
Engine Controls?

-

Go to Step 2

Go to

Diagnostic

System Check -

Engine Controls

2

1. Turn OFF the ignition.

2. Remove the air inlet duct from the throttle body.

3. Disconnect the throttle body harness connector.

4. Connect the jumper wires between the throttle

position (TP) sensor 1 terminals of the throttle
body harness connector and the corresponding
TP sensor 1 terminals of the throttle body.

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

6. Close the throttle blade by hand.

7. Observe the TP sensor 1 voltage with a scan tool.

Is the TP sensor 1 voltage within the specified range?

0.37-

0.71 V

Go to Step 5

Go to Step 3

3

1. Turn OFF the ignition.

2. Connect jumper wires between the TP sensor 2

terminals of the throttle body harness connector
and the corresponding TP sensor 2 terminals of
the throttle body.

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

4. Close the throttle blade by hand.

5. Observe the TP sensor 2 voltage with a scan tool.

Is the TP sensor 2 voltage within the specified range?

0.28-

0.81 V

Go to Step 9

Go to Step 4

4

Is DTC U0107 also set?

-

Go to

Diagnostic

Trouble Code

(DTC) List

Go to Step 9

5

1. Open the throttle blade to wide open throttle

(WOT) by hand.

2. Observe the TP sensor 1 voltage parameter on

the scan tool.

Is the TP sensor 1 voltage parameter more than the
specified value?

4.51 V

Go to Step 9

Go to Step 6

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2

6

1. Disconnect the TP sensor harness connector.

2. Disconnect the throttle actuator control (TAC)

module harness connector containing the TP
sensor circuits.

3. Test the TP sensor low-reference circuit for a

short to ground with a DMM. Refer to Circuit
Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

-

Go to Step 32

Go to Step 7

7

1. Turn OFF the ignition for 15 seconds.

2. Connect the TAC module harness connector.

3. Connect the throttle body harness connector.

4. Install the air inlet duct.

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

6. Select the DTC Info option on the scan tool.

7. Lightly touch and move the related engine wiring

harnesses and connectors for the TP sensor while
observing the DTC Info. The DTC will set if an
intermittent condition is present. Refer to
Connector Repairs and Wiring Repairs in
Wiring Systems.

Did you find and correct the condition?

-

Go to Step 32

Go to Step 8

8

1. Continue to observe the DTC Info.

2. Slowly depress the accelerator pedal to WOT,

then slowly return the pedal to the released
position 3 times.

Does the scan tool indicate this DTC failed this
ignition?

-

Go to Step 27

Go to Diagnostic

Aids

9

1. Disconnect the TP sensor harness connector.

2. Measure the voltage at the TP sensor 1 signal

circuit with a DMM connected to ground.

Is the voltage within the specified range?

3.94-

6.06 V

Go to Step 14

Go to Step 10

10

1. Turn OFF the ignition.

2. Disconnect the TAC module harness connector

containing the TP sensor circuits.

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

4. Test the TP sensor 1 signal circuit for a short to

voltage with a DMM. Refer to Circuit Testing

-

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2

and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 32

Go to Step 11

11

Test the TP sensor 1 signal circuit for an open or high
resistance with a DMM. Refer to Circuit Testing and
Wiring Repairs in Wiring Systems.
Did you find and correct the condition?

-

Go to Step 32

Go to Step 12

12

Test the TP sensor 1 signal circuit for a short to ground
with a DMM. Refer to Circuit Testing and Wiring
Repairs in Wiring Systems.
Did you find and correct the condition?

-

Go to Step 32

Go to Step 13

13

1. Disconnect the other TAC module harness

connector.

2. Test for a short between the TP sensor 1 signal

circuit and all other TAC module circuits with a
DMM. Refer to Circuit Testing and Wiring
Repairs in Wiring Systems.

Did you find and correct the condition?

-

Go to Step 32

Go to Step 28

14

Measure the voltage from the TP sensor 1 5-volt
reference circuit to a good ground with a DMM. Refer
to Circuit Testing in Wiring Systems.
Is the voltage within the specified range?

4.54-

5.21 V

Go to Step 24

Go to Step 15

15 Is the voltage more than the specified value?

5.21 V

Go to Step 16

Go to Step 18

16

1. Turn OFF the ignition.

2. Disconnect the TAC module harness connector

containing the TP sensor circuits.

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

4. Test the TP sensor 1 5-volt reference circuit for a

short to voltage with a DMM. Refer to Circuit
Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

-

Go to Step 32

Go to Step 17

17

1. Turn OFF the ignition.

2. Disconnect the accelerator pedal position (APP)

sensor harness connector.

3. Disconnect the other TAC module harness

connector.

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

5. Test the APP sensor 1 5-volt reference circuit for

a short to voltage with a DMM. Refer to Circuit
Testing and Wiring Repairs in Wiring Systems.

-

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2

Did you find and correct the condition?

Go to Step 32

Go to Step 22

18

Disconnect the APP sensor.
Is the voltage less than the specified value?

4.54 V

Go to Step 19

Go to Step 30

19

1. Disconnect the TAC module harness connector

containing the TP sensor circuits.

2. Test the TP sensor 1 5-volt reference circuit for

an open or high resistance with a DMM. Refer to
Circuit Testing and Wiring Repairs in Wiring
Systems.

Did you find and correct the condition?

-

Go to Step 32

Go to Step 20

20

Test the TP sensor 1 5-volt reference circuit for a short
to ground with a DMM.
Did you find and correct the condition?

-

Go to Step 32

Go to Step 21

21

Test the APP sensor 1 5-volt reference circuit for a
short to ground with a DMM. Refer to Circuit Testing
and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?

-

Go to Step 32

Go to Step 22

22

Test for a short between the TP sensor 1 5-volt
reference circuit and all other TAC module circuits
with a DMM. Refer to Circuit Testing and Wiring
Repairs in Wiring Systems.
Did you find and correct the condition?

-

Go to Step 32

Go to Step 23

23

Test for a short between the APP sensor 1 5-volt
reference circuit and all other TAC module circuits
with a DMM. Refer to Circuit Testing and Wiring
Repairs in Wiring Systems.
Did you find and correct the condition?

-

Go to Step 32

Go to Step 28

24

1. Connect a fused jumper between the TP sensor 1

low reference circuit and the TP sensor 1 signal
circuit.

2. Observe the TP sensor 1 voltage parameter with

a scan tool.

Is the TP sensor 1 parameter near the specified value?

0 V

Go to Step 26

Go to Step 25

25

1. Turn OFF the ignition.

2. Disconnect the TAC module harness connector

containing the TP sensor circuits.

3. Test the TP sensor 1 low-reference circuit for an

open or high resistance with a DMM. Refer to
Circuit Testing and Wiring Repairs in Wiring
Systems.

Did you find and correct the condition?

-

Go to Step 32

Go to Step 28

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2