Hummer H1 (2006+). Manual - part 136

OBD-388

On-Board Diagnostics

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    10

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 11 

    11

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnos-

tic Trouble 

Code (DTC) 

List

System OK

Step

Action

Value(s)

Yes

No

6-1-05

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 On-Board Diagnostics  OBD-389

5745804

DTC P1125 Accelerator Pedal Position (APP) System (Figure OBD-101)

Figure OBD-101:   Accelerator Pedal Position 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 one 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 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 fuel injector control. If the ECM detects a condition with more than one sensor within the APP sen-
sor, DTC P1125 sets.

OBD-390

On-Board Diagnostics

_____________________________________________

Conditions for Setting the DTC 

• The ECM detects a condition with more than one APP sensor. 

• All of the above conditions 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. 

Diagnostic Aids 

• The APP sensor 2 5-volt reference circuit is shared with the barometric pressure (BARO) sensor and the turbo boost sole-

noid and they are internally connected within the ECM. 

• For an intermittent, refer to Intermittent Conditions . 

 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

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 On-Board Diagnostics  OBD-391

5745804

Step

Action

Value(s)

Yes

No

    1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to           

Diagnostic

System Check 

    2

Is DTC P0642, P0643, P0652, P0653, P0698, or P0699 also set?

Go to Diagnos-

tic Trouble 

Code (DTC) 

List - Vehicle in 

Vehicle DTC 

Information

Go to Step 3 

    3

This DTC indicates that 2 or more accelerator pedal position
(APP) sensor DTCs are set.

Are other APP sensor DTCs set?

Go to Diagnos-

tic Trouble 

Code (DTC) 

List - Vehicle in 

Vehicle DTC 

Information