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4LHD/4LHDX Application Manual
Powertrain Control Solutions
REV 1.1
Electrical Inputs
Sensors monitor the engine and transmission parameters, and provide the inputs to the TCM. The following inputs are
external to the transmission and must be supplied to the TCM:
• Ignition voltage
• Brake status
• Engine speed
• Throttle position
• Serial data (diagnostics)
Discrete Inputs
CAN Communication
:
The PCS TCM can receive and transmit data over CAN. J1939 is supported as well as PCS
proprietary communication. Refer to the document
PCS J1939 Messages
for more information. If CAN is not available for
receiving inputs, refer to the discrete signal descriptions below.
Brake Switch:
This line is either open or switches to ignition voltage or ground externally supplied to the switch. Under
normal conditions ignition voltage is present. This input can be set to be active high or active low.
Diagnostic Enable:
The diagnostic request line enables the dashboard malfunction code feature. The single line is either
open or grounded. Due to the Fault detection hardware of the TCM output circuitry an incandescent bulb is require. LEDs
can potentially illuminate falsely.
Position (Transmission Range):
The position indication is from three discrete inputs from an Internal Mode Switch
mounted inside the transmission on the shift lever.
The following external inputs are optional:
• Shift pattern select
• Engine coolant temperature
• Diagnostic enable
The following inputs are internal to the transmission:
• Position (transmission range)
• Input speed
• Transmission fluid temperature
• Output speed
The inputs are either:
• Discrete
• Analog
• Discrete Frequency
• Bi-directional
Analog Inputs
Ignition Voltage:
Ignition voltage is an analog input to the Control Module to determine ignition status. It should have an
operation range of 0 to 25.5 volts.
Throttle Position:
The throttle position is an analog input requiring a three wire interface (reference voltage, signal and
ground) to a potentiometer.
Transmission Fluid Temperature:
The transmission fluid temperature is measured from a thermistor located in the
pressure switch manifold. It has an operating range from -40°C to 150°C (-40°F to 302°F).