Hummer H1 (2006+). Manual - part 140

 

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Hummer H1 (2006+). Manual - part 140

 

 

OBD-404

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 using the scan tool.

2.

Lightly touch and move the related accelerator pedal position 
(APP) wiring harnesses and connectors while monitoring the 
DTC information.

Did this DTC fail this ignition during the above test?

Go to Step 10 

Go to Intermit-

tent Conditions 

    4

1.

Disconnect the APP sensor harness connector.

2.

Turn ON the ignition, with the engine OFF.

3.

Test for voltage at the APP sensor 1 5-volt reference circuit 
717 (TN) with a DVOM.

Does the DVOM indicate voltage more than the specified value?

5 Volts

Go to Step 5

Go to Step 6

    5

1.

Connect a fused jumper between the APP sensor 1 5-volt ref-
erence circuit 717 (TN) and the APP sensor 1 signal circuit 
718 (DB).

2.

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

3.

Does the scan tool indicate APP sensor 1 voltage at the spec-
ified value?

5 Volts

Go to Step 11

Go to Step 8

    6

1.

Disconnect C75 (ECM) harness connector containing the 
APP sensor 1 5-volt reference circuit 717 (TN).

2.

Test the APP sensor 1 5-volt reference circuit 717 (TN) for a 
short to ground. 

Did you find and correct the condition?

Go to Step 15 

Go to Step 7

    7

Test the APP sensor 1 5-volt reference circuit 717 (TN) for an
open or high resistance.

Did you find and correct the condition?

Go to Step 15 

Go to Step 12

    8

1.

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

2.

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

Did you find and correct the condition?

Go to Step 15

Go to Step 9

    9

Test the APP sensor 1 signal circuit 718 (DB) for an open or high
resistance.

Did you find and correct the condition?

Go to Step 15 

Go to Step 12 

    10

Repair the intermittent condition as necessary. 

Did you complete the repair?

Go to Step 15 

    11

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

Did you find and correct the condition?

Go to Step 15 

Go to Step 13

Step

Action

Value(s)

Yes

No

_____________________________________________

 On-Board Diagnostics  OBD-405

5745804

    12

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

Did you find and correct the condition?

Go to Step 15 

Go to Step 14

    13

Replace the faulty APP sensor assembly. 

Did you complete the replacement?

Go to Step 15 

    14

Replace the faulty ECM. 

Did you complete the replacement?

Go to Step 15 

    15

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 Step16

    16

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-406

On-Board Diagnostics

_____________________________________________

DTC P2123 Accelerator Pedal Position (APP) Sensor 1 Circuit High Voltage (Figure OBD-106)

Figure OBD-106:   Accelerator Pedal Position (APP) Sensor 1 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 in the APP sensor 1 circuit, DTC P2123
sets.

_____________________________________________

 On-Board Diagnostics  OBD-407

5745804

Conditions for Setting the DTC 

• The APP sensor 1 voltage is more than 4.75 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 cen-

ter 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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