Hummer H2. Manual - part 1578

Circuit Description 

The commanded throttle position (TP), based on accelerator pedal position (APP) and possibly other limiting 
factors, is compared to the actual TP. The two values should be within a calibrated range of each other. Both the 
powertrain control module (PCM) and the throttle actuator control (TAC) module redundantly monitor the 
commanded and actual TP. This DTC sets if the PCM detects an out-of-range condition between the 
commanded and the actual throttle position. 

Conditions for Running the DTC 

z

DTCs P0601, P0602, P0604, P0606, P1516, P2108, U0107 are not set.  

z

DTCs P0120 and P0220 are not active at the same time.  

z

The ignition switch is in the Crank or Run position.  

z

The ignition voltage is more than 8.5 volts.  

z

The TAC system is not in the battery saver mode.  

Conditions for Setting the DTC 

z

The PCM detects that the commanded and actual throttle positions are not within a calibrated range of 
each other.  

z

The above condition is met for less than 1 second.  

Action Taken When the DTC Sets 

z

The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. 

z

The control module records the operating conditions at the time the diagnostic fails. The control module 
stores this information in the Freeze Frame and/or the Failure Records.  

z

The control module commands the TAC system to operate in the Reduced Engine Power mode.  

z

A message center or an indicator displays Reduced Engine Power.  

z

Under certain conditions the control module commands the engine OFF.  

Conditions for Clearing the MIL/DTC 

z

The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles 
that the diagnostic runs and does not fail.  

z

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

z

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

z

Clear the MIL and the DTC with a scan tool.  

Diagnostic Aids 

z

Inspect for mechanical concerns or binding that may be temperature related. Components may not move 
freely in extreme heat or cold due to the presence of contaminants or ice formation.  

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0507 (TAC) To DTC U0107) - 4.8L, 5.3L, and 6.0L - 

Hummer H2

  

z

Inspect the TAC module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs 
may set without any circuit or component conditions found during diagnostic testing.  

z

When the TAC module detects a condition within the TAC system, more than one TAC system related 
DTC may set. This is due to the many redundant tests run continuously on this system. Locating and 
repairing an individual condition may correct more than one DTC. Disconnecting components during 
testing may set additional DTCs. Remember this if you review the stored information in Capture Info.  

z

For an intermittent, refer to Intermittent Conditions .  

Test Description 

The numbers below refer to the step numbers on the diagnostic table. 

4: If the TP indicated angle does not follow the movement of the throttle blade and no TP sensor DTCs 
are set, there is a mechanical condition with the throttle shaft or the TP sensor.  

15: Locating and repairing an individual condition may correct more than 1 DTC.  

DTC P2101 

Step

Action

Yes

No

Schematic Reference:Engine Controls Schematics 
Connector End View Reference:Engine Controls Connector End 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

Is DTC U0107 also set?

Go to DTC 

U0107

Go to Step 2

3

1. Turn OFF the ignition for 15 seconds.  

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

3. Observe the throttle position (TP) sensor 1 and TP 

sensor 2 angle parameters with a scan tool.  

4. Slowly depress the accelerator pedal to wide open 

throttle (WOT) and slowly return the pedal to the 
released position.  

Does the scan tool indicate both angle parameters 
increasing as the pedal is depressed to WOT and 
decreasing as the pedal is moved to the released position?

IMPORTANT:

The next test must be started within 15 seconds after 
the ignition is turned ON.

Go to Diagnostic 

Aids

Go to Step 4

1. Turn OFF the ignition.  

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

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0507 (TAC) To DTC U0107) - 4.8L, 5.3L, and 6.0L - 

Hummer H2

  

4

3. Disconnect the throttle body harness connector.  

4. Connect the jumper wires between the TP sensor 

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

5. Turn ON the ignition with the engine OFF.  

6. Open the throttle blade to WOT, then to the closed 

position by hand.  

7. Observe the TP sensor 1 and the TP sensor 2 angle 

parameters with a scan tool.  

Does the scan tool indicate both angle parameters 
increasing as the throttle plate is moved to WOT, and 
decreasing as the throttle plate is moved to the closed 
position?

Go to Step 5

Go to Step 12

5

1. Turn OFF the ignition.  

2. Disconnect the throttle actuator control (TAC) 

module harness connector containing the TAC motor 
circuits.  

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

4. Test the TAC motor circuits 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 14

Go to Step 6

6

Test each TAC motor 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 14

Go to Step 7

7

Test each TAC motor 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 14

Go to Step 8

8

1. Disconnect the other TAC module harness 

connector.  

2. Remove all jumper wires.  

3. Test for a short between each TAC motor 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 14

Go to Step 9

1. Turn OFF the ignition.  

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0507 (TAC) To DTC U0107) - 4.8L, 5.3L, and 6.0L - 

Hummer H2

  

DTC P2108 

Circuit Description 

The throttle actuator control (TAC) module contains data which is essential for proper TAC system operation. 
The TAC module continuously tests the integrity of this data. When the TAC module is unable to write or read 
data to and from random access memory (RAM), or the TAC module is unable to correctly read data from the 

9

2. Connect the TAC module.  

3. Connect a test lamp between the 2 TAC motor 

circuits at the TAC motor harness connector.  

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

observe the test lamp.  

Did the test lamp illuminate briefly when the ignition was 
turned ON?

Go to Step 10

Go to Step 12

10

Inspect for poor connections at the TAC motor harness 
connector. Refer to Testing for Intermittent Conditions 
and Poor Connections and Repairing Connector 
Terminals in Wiring Systems. 
Did you find and correct the condition?

Go to Step 14

Go to Step 11

11

Replace the throttle body assembly. Refer to Throttle 
Body Assembly Replacement . 
Did you complete the replacement?

Go to Step 14

-

12

Inspect for poor connections at the TAC module harness 
connectors. Refer to Testing for Intermittent Conditions 
and Poor Connections and Repairing Connector 
Terminals in Wiring Systems. 
Did you find and correct the condition?

Go to Step 14

Go to Step 13

13

Replace the TAC module. Refer to Throttle Actuator 
Control (TAC) Module Replacement . 
Did you complete the replacement?

Go to Step 14

-

14

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 15

15

Observe the Capture Info with a scan tool. 
Are there any DTCs that have not been diagnosed?

Go to Diagnostic 

Trouble Code 

(DTC) List

System OK

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0507 (TAC) To DTC U0107) - 4.8L, 5.3L, and 6.0L - 

Hummer H2