Hummer H1 Service Manual page 1127

62 PCM/Tech 1 Scan Tool
DTC P0227 Accelerator Pedal Position (APP)
Sensor 3 Circuit Low Voltage
Circuit Description
The Accelerator Pedal Position (APP) module provides a volt-
age signal that changes relative to accelerator position. There
are three sensors located within the APP module that are scaled
differently. This is a type C DTC.
Conditions for Setting the DTC
• Voltage is less than .25 volts on APP 3 sensor.
• Conditions met for 2 seconds.
Action Taken When the DTC Sets
• The input from APP 3 sensor is ignored.
• A current and history DTC will set but it will not turn on
the "Service Throttle Soon" lamp.
• The throttle will operate normally as long as there is
only one sensor malfunction present. If two different
APP sensors have a malfunction, the "Service Throttle
Soon" lamp will light and the PCM will limit power. If
three APP sensors have a malfunction present, the "Ser-
vice Throttle Soon" lamp will light and the PCM will
only allow the engine to operate at idle.
_____________________________________________________
ACCELERATIOR
PEDAL POSITION
SENSOR
44
D B
32
C
2
53
G A
17
F
1
60
E
J
15
K
3
14
20
HOT IN RUN
22
AND START
C1
FUSE 3A
10 AMP
EXTERIOR
C5-A4
A
RESUME
ACCEL
HOT IN RUN
AND START
SET
COAST
FUSE 5C
10AMP
INTERIOR B
ON/
295 BR OFF
722 PP C29-A12
721 LB C27-C5
719 BR C29-B1
718 DB C29-B2
725 GY C27-D6
724 DG C27-D4
723 YL C27-D3
717 WH C27-D12
720 TN C28-C2
C5-D3
B
154 TN C28-D14
C
37 C27-D10
YL 153 LG
D
42
C29-B11
GRN 152 DB
A 29
RD 151 GY C29-A11
C1
Conditions for Clearing the MIL/DTC
• A History DTC will clear when forty consecutive
warm-up cycles that the diagnostic does not fail (coolant
temperature has risen 5°C (40°F) from start up coolant
temperature and engine coolant temperature exceeds
71°C (160°F) that same ignition cycle).
• Use of a Scan Tool
Diagnostic Aids
A scan tool reads APP 3 position in volts and should read about
4.0 volts with throttle closed and ignition "ON" or at idle. Volt-
age should decrease at a steady rate as throttle is moved toward
Wide Open Throttle (WOT). Also 90% pedal travel is accept-
able for correct APP operation. Scan APP 3 sensor while de-
pressing accelerator pedal with engine stopped and ignition
"ON", Display should vary from about 4.0 volts when throttle
was closed to about 2.0 volts when throttle is held at Wide
Open Throttle (WOT) position. Refer to "Intermittents", in
Section 2.
Test Description
Number(s) below refer to the circled number(s) on the diagnos-
tic table.
2. This step determines if P0227 is the result of a hard failure or
an intermittent condition.
3. This step checks the PCM and wiring.
POWERTRAIN
CONTROL
MODULE
(PCM)
GROUND
APP 2
SIGNAL
GROUND
APP 1
SIGNAL
GROUND
APP 3
SIGNAL
5 VOLT
REFERENCE
WASTEGATE
SOLENOID
CONTROL
RESUME
ACCEL
SIGNAL
SET
COAST
SIGNAL
ON / OFF
SIGNAL
9-S12-055
®