Hummer H1 (2006+). Manual - part 141

 

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Hummer H1 (2006+). Manual - part 141

 

 

OBD-408

On-Board Diagnostics

_____________________________________________

    2

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.

Does the DTC fail this ignition?

Go to Step 4

Go to Step 3

    3

1.

Select the DTC option on the scan tool.

2.

Lightly touch and move the related accelerator pedal position 
(APP) sensor wiring harnesses and connectors while moni-
toring the DTC information.

Did this DTC fail this ignition during the above test?

Go to Step 9 

Go to Intermit-

tent Conditions 

    4

1.

Disconnect the APP sensor harness connector.

2.

Turn ON the ignition, with the engine OFF.

3.

Observe the APP sensor 1 voltage parameter with a scan 
tool.

Does the scan tool indicate the APP sensor 1 voltage at the speci-
fied value?

0 Volts

Go to Step 5 

Go to Step 6 

    5

1.

Connect a fused jumper between the APP sensor 2 signal cir-
cuit 721 (LB) and the APP sensor 1 low reference circuit 722 
(PP).

2.

Observe the APP sensor 2 voltage parameter with a scan 
tool.

3.

Does the scan tool indicate APP sensor 2 voltage at the spec-
ified value?

0 Volts

Go to Step 10

Go to Step 8

    6

1.

Turn OFF the ignition.

2.

Disconnect C76 (ECM) harness connector containing the 
APP sensor 1 signal circuit 718 (DB).

3.

Turn ON the ignition.

4.

Test the APP sensor 1 signal circuit 718 (DB) for a short to 
voltage.

Did you find and correct the condition?

Go to Step 14

Go to Step 7

    7

1.

Turn OFF the ignition.

2.

Disconnect the other ECM harness connector.

3.

Test the APP sensor 1 signal circuit 718 (DB) for a short to 
all other APP circuits at the APP sensor harness connector. 

Did you find and correct the condition?

Go to Step 14 

Go to Step 11

    8

1.

Disconnect C76 ECM harness connector containing the APP 
sensor 1 low reference circuit 719 (BR).

2.

Test the APP sensor 1 low reference circuit 719 (BR) for an 
open or high resistance. 

Did you find and correct the condition?

Go to Step 14 

Go to Step 11

    9

Repair the intermittent condition as necessary. 

Did you complete the repair?

Go to Step 14 

    10

Inspect for poor connections at the harness connector of the APP
sensor.

Did you find and correct the condition?

Go to Step 14 

Go to Step 12 

Step

Action

Value(s)

Yes

No

_____________________________________________

 On-Board Diagnostics  OBD-409

5745804

    11

Inspect for poor connections at the harness connector of the
ECM.

Did you find and correct the condition?

Go to Step 14 

Go to Step 13

    12

Replace the faulty APP sensor assembly. 

Did you complete the replacement?

Go to Step 14 

    13

Replace the faulty ECM. 

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 Diagnos-

tic Trouble 

Code

System OK

Step

Action

Value(s)

Yes

No

6-1-05

OBD-410

On-Board Diagnostics

_____________________________________________

DTC P2127 Accelerator Pedal Position (APP) Sensor 2 Circuit Low Voltage (Figure OBD-107)

Figure OBD-107:   Accelerator Pedal Position (APP) Sensor 2 Circuit

Circuit Description

The accelerator pedal position (APP) sensor is mounted on the accelerator pedal control assembly. The sensor is made up of 3 indi-
vidual sensors within 1 housing. Three separate signal, low reference, and 5-volt reference circuits are used in order to interface the
APP sensor with the engine control module (ECM). Each sensor has a unique functionality to determine the pedal position as
shown in the table below. The ECM uses the APP sensor to determine the amount of acceleration or deceleration desired by the
person driving the vehicle via the fuel injector control. If the ECM determines high voltage with the APP sensor 2 circuit, DTC
P2127 sets.

_____________________________________________

 On-Board Diagnostics  OBD-411

5745804

Conditions for Setting the DTC 

• The APP sensor 2 voltage is less than 0.25 volts. 

• The above condition is present for less than 1 second. 

Action Taken When the DTC Sets 

• The control module stores the DTC information into memory when the diagnostic runs and fails. 

• The malfunction indicator lamp (MIL) will not illuminate. 

• The control module records the operating conditions at the time the diagnostic fails. The control module stores this informa-

tion in the Failure Records. 

• If one or more APP sensor DTCs are set for a single APP sensor, the following occurs: 

•  The control module will not command Reduced Engine Power mode. 

•  The control module will use the remaining two APP sensors to calculate throttle response. 

• If certain multiple APP sensor DTCs are set for more than one APP sensor, the following occurs: 

•  The control module commands Reduced Engine Power mode. 

•  The APP indicated angle is limited to a predetermined value to limit the amount of throttle control. 

•  The message center displays Reduced Engine Power. 

• If all three APP sensors are out of range, the following occurs: 

•  The control module commands Reduced Engine Power mode. 

•  The APP indicated angle is limited to 0 percent. The control module only allows the engine to idle. 

•  The message center displays Reduced Engine Power. 

Conditions for Clearing the DTC 

• 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 non-emission re-

lated diagnostic. 

• Clear the DTC with a scan tool. 

 APP 

 Sensor

ActualPedal

Position

 % Depressed as Observed 

on a Scan Tool

 Voltage as Observed on a Scan 

Tool

1

Pedal at rest

0

.52 - .80

1

Pedal at full travel

100

2.12 - 2.78

2

Pedal at rest

0

4.25 - 4.53

2

Pedal at full travel

100

2.24 - 2.93

3

Pedal at rest

0

3.95 - 4.13

3

Pedal at full travel

100

2.69 - 3.16

Step

Action

Value(s)

Yes

No

    1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnos-

tic System 

Check

 

 

 

 

 

 

 

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