Accelerator Pedal Position Sensor/IVS Switch (APS/IVS) Página 1 de 2
Accelerator Pedal Position Sensor/I VS Switch (APS/I VS)
DTC:
131 132 133 134 135
Figure(s) and Table(s):
V8 I6
Signal Functions:
The Accelerator Pedal Position Sensor (APS) is a potentiometer type sensor. When the APS receives a 5V reference signal
and a ground from the Electronic Control Module (ECM), a linear analog voltage signal from the sensor will indiccate the
driver's demand for power. The Idle Validation Switch (IVS) provides 0V or 12V to the ECM as redundant signal to verify
the pedal idle position.
Fault Detection and M anagement:
Any detected malfunction of the APS/IVS sensor circuit will illuminate the amber ENGINE lamp and the odometer will
display WARN ENG. If the ECM detects an APS signal Out of Range HIGH or LOW, the engine will ignore the APS
signal and operate at low idle. If a disagreement in the state of IVS and APS is detected by the ECM and the ECM
determines that it is an IVS fault, the ECM will only allow a maximum of 50% APS to be commanded. If the ECM cannot
discern if it is an APS or IVS fault, the engine will be allowed to operate at low idle only.
APS/I VS Extended System Description:
International electronic engines use an electronic accelerator pedal assembly that includes a Accelerator Position Sensor
(APS) and Idle Validation Switch (IVS). These two functions are integrated into one component mounted on the pedal. The
accelerator pedal assembly is serviceable to the extent that the APS/IVS switch can be replaced without replacing the
complete assembly
The engine Electronic Control Module (ECM) determines the position of the accelerator pedal by processing the input signals
from the Accelerator Position Sensor (APS) and Idle Validation switch (IVS).
The accelerator pedal position is one of the controlling variables in the calculation of desired injection control pressure.
Accelerator Position Sensor (APS):
The ECM sends a regulated 5 volt signal through the ECM chassis connector (black) terminal 3 to APS connector terminal
C. The APS then returns a variable voltage signal (depending on pedal position) from the APS connector terminal A to the
ECM at terminal 8. The APS is grounded from connector terminal B to the ECM signal ground terminal 11. System
Diagrom for Accelerator, BAP, and Intake Air Temperature sensors.
APS Auto-Calibration:
The ECM learns the lowest and highest pedal positions by reading and storing the minimum and maximum voltage levels
from the APS. In this manner the ECM "auto- calibrates" the system to allow maximum pedal sensitivity. The ECM auto-
calibrates as the key is ON, but when the key is turned OFF, these values are lost. When the key is turned on again, this
process starts over. When the pedal is disconnected (or new one installed), the pedal does not need to be calibrated. It
simply "auto-calibrates" the new pedal assembly whenever the key is turned ON again.
mk:@MSITStore:C:\Navistar\MD_ML\Language\English\MD32_DLC.chm::/TCode_DL... 08/12/2021
Accelerator Pedal Position Sensor/IVS Switch (APS/IVS) Página 2 de 2
I dle Validation Switch:
The ECM expects to receive one of two signals through the ECM chassis connector (black) terminal 27 from APS/IVS
connector terminal D:
0 volts when the pedal is at the idle position.
12 volts when the pedal is depressed.
The Idle Validation Switch receives 12 volt ignition voltage from the switched ignition fuse in the fuse box. When the pedal
is NOT in the idle position (throttle applied), the IVS supplies a 12 volt signal to the ECM.
The ECM compares the APS/IVS inputs it receives at terminals 8 and 27 to verify when the pedal is in the idle position. If
the APS signal at terminal 8 indicates throttle is being applied, the ECM expects to see 12V at IVS terminal 27. If the APS
signal at terminal 8 indicates throttle is not applied, the ECM expects to see 0V at the IVS terminal 27. The timing process is
critical between the APS and the IVS sensors. For this reason, it is very difficult to determine if the APS/IVS assembly is
working properly using a digital multimeter (DMM).
ECM Diagnostics:
When the key is ON, the ECM continuously monitors the APS/IVS circuits for expected voltages. It also compares the APS
and IVS signals for conflicts. If the signals are not what the ECM expects to see. Diagnostic Trouble Codes will be set.
Diagnostic Trouble Codes can be retrieved using the Electronic Service Tool (EST) or by reading the Diagnostic Trouble
Code flashes from the amber and red ENGINE lamps.
Flash Codes 133, 134 and 135
APS I n-Range Faults:
The ECM checks the voltage output of the APS by comparing the APS signal with the IVS signal. APS and IVS signals can
disagree in two cases:
The APS signal indicates the pedal is pressed down to accelerate, but the IVS signal indicates idle position.
The APS signal indicates the pedal has been released to allow the engine to return to idle, but the IVS signal indicates
off-idle position.
If the ECM detects either of the above conditions, the ECM attempts to isolate the source of conflict and set the appropriate
Diagnostic Trouble Code.
mk:@MSITStore:C:\Navistar\MD_ML\Language\English\MD32_DLC.chm::/TCode_DL... 08/12/2021
