Download P2138 (3.6L V6 VIN 7 Auto) Accelerator Pedal Position

Trouble Code: P2138 (3.6L V6 VIN 7
Auto)
Accelerator Pedal Position Sensor 1-2
Correlation Error
Print this code data
Number of Trips to Set Code: 1


OBD II Monitor Type: CCM Details
Indicators: MIL Details
CCM Details
MIL Details
Trouble Code Conditions:
DTC P0101, P0121, P0122, P0123, P0221, P0222, P0223, P2122, P2123,
P2127 and P2128 not set, key on, system voltage over 10v, accelerator
pedal not at "rest" position, and the PCM detected the difference between
APP Sensor 1 and APP Sensor 2 was more than the predicted value. The
accelerator pedal position (APP) sensor is made up of two sensors that are
housed inside one assembly. The PCM supplies a separate 5v VREF and
low reference circuit for each of the sensors. The 5v VREF for APP Sensor
1 is supplied from the same source in the PCM as the 5v VREF for the
MAF sensor and the FTP sensor. The 5v VREF for APP Sensor 2 is
supplied from the same source in the PCM as the 5v VREF for the TP
sensors. The 5v VREF voltage for all of the sensors is supplied on separate
PCM terminals, but the terminals are connected internally to the shared
voltage supply. The APP sensor sends a signal from each of the sensors to
the PCM indicating the accelerator pedal position. The PCM actuates the
throttle plates based on this information. The APP Sensor 1 signal voltage
increases as the throttle opens, from about 0.4v at closed throttle to above
3.5v at wide-open throttle (WOT). The APP Sensor 2 signal voltage
increases as the throttle opens, but at a slightly different rate. The APP
Sensor 2 signal increases from about 0.2v at closed throttle to about 1.8v at
WOT. The PCM compares the signal of each of the APP sensors, when the
pedal is not in the rest position. If the PCM detects the APP sensors are not
within a predicted value from each other, DTC P2138 is set.
Possible Causes:
 APP Sensor 1 signal circuit is shorted to the APP2 signal circuit
 APP sensor is damaged or it has failed
PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls Print
3.6L (LY7) > DTC P2138
DTC P2138
NOTE
Applicable vehicles:
 CTS (VIN D)
 SRX (VIN E)
 STS (VIN D)
DTC P2138
Circuit Description
The accelerator pedal assembly contains 2 accelerator pedal position (APP) sensors.
The APP sensors are mounted in the pedal assembly and are not serviceable. The APP
sensors provide a signal voltage that changes relative to the position of the accelerator
pedal. The engine control module (ECM) supplies a separate 5-volt reference and low
reference circuit for each of the APP sensors.
The APP sensor 1 signal voltage increases as the pedal is depressed, from
approximately 1.0 volt at rest to above 4 volts when fully depressed. The APP sensor 2
signal voltage increases as the pedal is depressed, from approximately 0.5 volt at rest to
more than 2 volts with the accelerator pedal fully depressed.
If the ECM detects that the difference between APP sensor 1 and 2 signal voltage is
more than a predetermined value, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2138 Accelerator Pedal Position (APP) Sensor 1-2 Correlation
Conditions for Running the DTC
 The battery voltage is more than 7.0 volts.
 The ignition is ON or the engine is operating.
 DTC P2138 run continuously once the above conditions are met for more than 1
second.
Conditions for Setting the DTC
This DTC set when one of the following conditions occur:
 The ECM detects that the voltage difference between APP sensor 1 and 2 is more
than 0.21 volt.
 The ECM detects that the voltage difference between APP sensor 1 and 2 is more
than 0.27 volt with a partially pressed pedal.
 The ECM detects that the voltage difference between APP sensor 1 and 2 is more
than 1.07 volts with a fully pressed pedal.
 The ECM detects that the APP sensor 1 voltage is more then 1.17 when leaving
the idle range and the voltage difference between APP sensor 1 and 2 is more
than 0.04.

Any of the above conditions exist for less than 4 seconds.
Action Taken When the DTC Sets
 The control module illuminates the malfunction indicator lamp (MIL) when the
diagnostic runs and fails.
 The control module records the operating conditions at the time the diagnostic
fails. The control module stores this information in the Freeze Frame/Failure
Records.
Conditions for Clearing the MIL/DTC
 The control module turns OFF the malfunction indicator lamp (MIL) after 4
consecutive ignition cycles that the diagnostic runs and does not fail.
 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 emission related diagnostic.
 Clear the MIL and the DTC with a scan tool.
Diagnostic Aids
 Use the J 35616-A/BT-8637 Connector Test Adapter Kit for any test that
requires probing the ECM harness connector or a component harness connector.
 The lower connector of the ECM is connector C1 and the upper connector of the
ECM is connector C2. Refer to Engine Controls Component Views.
 If DTCs P0700, P2122, P2128, and P2138 are set together in various
combinations, inspect the APP sensor 1 and 2 signal circuits for being shorted
together.
 For an intermittent condition, refer to Intermittent Conditions.
DTC P2138 Accelerator Pedal Position (APP) Sensor 1-2 Correlation
Step
Action
Values
Yes
No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Control Module Connector End Views or
Engine Controls Connector End Views
1
Did you perform the Diagnostic System Check Vehicle?
--
Go to
Diagnostic
Go to Step
System
2
Check Vehicle
2
1. Turn ON the ignition, with the
engine OFF.
2. Perform the following tests:
 Rapidly depress the
accelerator pedal from
--
Go to Step Go to Step
4
3
Step
Action
the rest position to the
wide open throttle
position (WOT) and
release pedal. Repeat
the procedure several
times.
 Slowly depress the
accelerator pedal to
WOT and then slowly
return the pedal to
closed throttle. Repeat
the procedure several
times.
3. Observe the accelerator pedal
position (APP) sensors 1 and 2
parameter with a scan tool.
Does the scan tool display Agree?
Values
Yes
No
3
Observe the DTC information with a scan tool.
Is DTC P0101, P0122, P0123, P0222, P0223,
P2122, P2123, P2127, P2128 also set?
--
Go to
Diagnostic
Go to Step
Trouble
5
Code
(DTC) List
- Vehicle
4
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.
Did the DTC fail this ignition?
Go to
Go to Step
Diagnostic
5
Aids
5
1. Turn OFF the ignition.
2. Disconnect the APP sensor
harness connector.
3. Turn ON the ignition, with the
4.8-5.1 Go to Step Go to Step
V
6
11
Step
Action
Values
Yes
No
engine OFF.
WARNING
Important: Use the J 35616200 Test Lamp Kit for this
test. If the J 35616-200 is
not available, use a test
lamp that measures more
than 20 ohms.
4. Connect a test lamp between
the 5-volt reference circuit of
the APP sensor 1 and a good
ground.
5. Connect a DMM to the probe
of the test lamp and a good
ground. Refer to Measuring
Voltage Drop.
Is the voltage within the specified range?
6
7
Important: Use the J 35616-200 for this
test. If the J 35616-200 is not available,
use a test lamp that measures more than
20 ohms.
1. Connect a test lamp between
the 5-volt reference circuit of
the APP sensor 2 and a good
ground.
2. Connect a DMM to the probe
of the test lamp and a good
ground. Refer to Measuring
Voltage Drop.
Is the voltage within the specified range?
1. Connect a 3-amp fused jumper
wire between the 5-volt
reference circuit and the signal
circuit of the APP sensor 1.
2. Observe the APP sensor 1
voltage parameter with a scan
4.8-5.1 Go to Step Go to Step
V
7
11
4.8 V
Go to Step Go to Step
8
12
Step
Action
Values
Yes
No
tool.
Is the voltage more than the specified value?
8
1. Connect a 3-amp fused jumper
wire between the 5-volt
reference circuit and the signal
circuit of the APP sensor 2.
2. Observe the APP sensor 2
voltage parameter with a scan
tool.
Is the voltage more than the specified value?
4.8 V
Go to Step Go to Step
9
12
5?
Go to Step Go to Step
10
13
5?
Go to Step Go to Step
14
13
1. Turn OFF the ignition.
2. Remove the engine control
module ECM/TCM fuse from
the underhood fuse block.
NOTE
9
Notice: Do NOT use a test
lamp to test the continuity
of the circuit. Damage to
the control module may
occur due to excessive
current draw.
3. Measure the resistance from
the low reference circuit of the
APP sensor 1 to the ECM
housing with a DMM.
Is the resistance less than the specified value?
NOTE
10
Notice: Do NOT use a test lamp to test the
continuity of the circuit. Damage to the
control module may occur due to excessive
current draw.
Step
Action
Values
Yes
No
Measure the resistance from the low reference
circuit of the APP sensor 2 to the ECM housing
with a DMM.
Is the resistance less than the specified value?
WARNING
Important: The engine control module
(ECM) for this engine is not equipped with
5-volt reference DTCs. The 5-volt reference
circuits are internally and externally
connected at the controller. Other sensors
that share the 5-volt reference circuit may
also have DTCs set. Disconnecting a sensor
on the shared 5-volt reference circuit may
isolate a shorted sensor. Review the
electrical schematic and diagnose the shared
circuits and sensors.
--
Go to Step Go to Step
19
16
12
Test the signal circuit of the APP sensor 1 or 2
for a high resistance, a short to ground, or for an
open. Refer to Circuit Testing and Wiring
-Repairs.
Did you find and correct the condition?
Go to Step Go to Step
19
16
13
Test the low reference circuit of the APP sensor
1 or 2 for a high resistance, or for an open.
Refer to Circuit Testing and Wiring Repairs.
Did you find and correct the condition?
--
Go to Step Go to Step
19
16
14
Test the signal circuit of APP sensor 1 for a
short to the signal circuit of APP sensor 2. Refer
-to Circuit Testing and Wiring Repairs.
Did you find and correct the condition?
Go to Step Go to Step
19
15
11
Test the 5-volt reference circuit of the APP
sensor 1 or 2 for a high resistance, a short to
ground, a short to voltage, or for an open. Refer
to Circuit Testing and Wiring Repairs.
Did you find and correct the condition?
Step
Action
Values
Yes
No
15
Test for an intermittent and for a poor
connection at the APP sensor. Refer to Testing
for Intermittent Conditions and Poor
Connections and Connector Repairs.
Did you find and correct the condition?
--
Go to Step Go to Step
19
17
16
Test for an intermittent and for a poor
connection at the ECM. Refer to Testing for
Intermittent Conditions and Poor
Connections and Connector Repairs.
Did you find and correct the condition?
--
Go to Step Go to Step
19
18
17
Replace the APP sensor. Refer to Accelerator
Pedal Position Sensor Replacement.
Did you compete the replacement?
--
Go to Step
-19
18
Replace the ECM. Refer to Control Module
References for replacement, setup, and
programming.
Did you complete the replacement?
--
Go to Step
-19
19
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 Go to Step
2
20
Observe the Capture Info with a scan tool.
Are there any DTCs that have not been
diagnosed?
Go to
Diagnostic
Trouble
System OK
Code
(DTC) List
- Vehicle
20
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