Open Circuit

TM 9-2320-312-24-2

Troubleshooting Section

Pro-Link Pro-Link is an electronic service tool

Oil Pressure Sensor This sensor measures engine

that is hand-held. The tool is manufactured by

oil pressure and the sensor signals the ECM.

Micro Processor Systems, Inc. (MPSI ). This tool

is supplied with a Caterpillar cartridge in order to

Open Circuit An open circuit is a condition that is

service a Caterpillar engine that is electronically

caused by an open switch, or an electrical wire or

controlled.

a connection is broken. When this condition exists,

the signal or the supply voltage can no longer reach

Progressive Shifting This is a method of upshifting

the intended destination.

through the lower gears quickly and not using

excessive engine rpm in each gear. Shifts are made

Original Equipment Manufacturer (OEM) The

above peak torque but below rated rpm. Using

OEM is the manufacturer of a vehicle that uses a

excessively high engine rpm ranges before shifting

Caterpillar engine for the power source.

to the next gear wastes fuel. Using the excessively

high engine rpm ranges also fails to take advantage

Parameter A parameter is a value or a limit that

of the torque rise of the engine. The two steps LoGr

is programmable. This helps determine specific

1 and LoGr 2 give the opportunity for progressive

characteristics or behaviors of the engine and/or

shifting. LoGr 1 is typically setat no lower than peak

vehicle.

torque plus 200 rpm. LoGr 2 is typically set at a

point that is midway between the LoGr 1 rpm limit

Parameter Identifier (PID) The PID is a two digit

and the top engine limit.

code or a three digit code which is assigned to

each component in order to identify data via the

PTO Configuration This is a programmable

data link to the ECM.

parameter that determines the best use of the ECM

input and the ECM output for PTO applications.

Passive Magnetic Speed Sensor (Vehicle) This

sensor is a vehicle speed sensor that does not

Pulse Width Modulation (PWM) The PWM is a

require a power and a ground connection. The

signal that consists of pulses that are of variable

sensor produces a signal that is based on the

width. These pulses occur at fixed intervals. The

change in magnetic flux of a ferrous metal gear

ratio of "time on" versus total "time off" can be

near the sensing tip.

varied. This ratio is also referred to as a duty cycle.

Password A password is a group of numeric

characters or a group of alphanumeric characters

that is designed to restrict access to parameters.

The electronic system requires correct passwords

in order to change customer specified parameters

(customer passwords) or certain engine

specifications (factory passwords). Passwords are

also required to clear certain diagnostic codes.

Pedal Mounted Accelerator Pedal Position Sensor

This sensor measures the position of the accelerator

pedal and the sensor sends a signal to the ECM.

The sensor is mounted on an accelerator pedal

assembly.

g00284479

Personality Module or Ratings Personality Module

Illustration 7

This module is attached to the inside of the

Rated Fuel Limit This term indicates the maximum

ECM. The module contains all the instructions

allowable fuel position (longest injection pulse). This

(software) for the ECM and the module contains the

position will produce rated power for this engine

performance maps for a specific horsepower family.

configuration.

Power Take-Off (PTO) The PTO operates with

Reference Voltage The reference voltage is a

the cruise control switches and the dedicated

regulated voltage and a steady voltage that is

PTO on/off switch. This mode permits the setting

supplied by the ECM to a sensor. The reference

of constant engine speeds or the mode permits

voltage is used by the sensor to generate a signal

varying the speed with either the accelerator pedal

voltage.

in the cab or a remote accelerator.