Challenger Terra Gator 3244 Chassis. Manual - part 115

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General Information

GENERAL INFORMATION

INTRODUCTION

The electrical system can be divided into four sections:

•

Engine;

•

Operator’s Station;

•

Electro Hydraulic;

•

Lighting.

Current to electrical systems is provided by a high output

alternator with a built-in voltage regulator. These high

output alternators are needed because, under certain

conditions, very high amperage demands are required.

The 12-volt batteries wired parallel have a double

negative ground-one to engine frame and one to starter.

A double connection is provided to ensure a reliable

ground.

BASIC TROUBLESHOOTING 
PROCEDURES

In troubleshooting electrical circuits the first step is to

familiaize yourself with the components, wire routing and

connections of the circuit. This can be aided by studying

the wiring diagrams in the operator’s or service manual.

Each electrical circuit on the machine is isolated to show

the wire connections and components used. Most

diagrams give a visual approximation of the components

to aid in identifying unfamiliar parts.

If a module or other electrical component is completely

dead, first check the diagram for the correct condition,

i.e., ignition switch on, clutches engaged, ect. Check for

obvious failure areas like fuses, unhooked connection or

broken wires. The ground circuit can also become

defective because of a broken wire or poor connection to

the frame. Most voltmeter probes are small enough to

insert into the back side of the electrical connectors so

the supply voltage to a module can be checked without

disconnecting it the harness.

The greatest percentage of defective connections occur

at or near the connectors themselves. Visually check to

see that terminals are completely inserted into the

housing (no terminal should be exposed above the

surface of the connector). This difficult in some

connectors below the console and may require removal

of the outside cover panel. If the locking tang on the

terminal is damaged and will not retain the terminal in

the connector, a new terminal from the electrical service

kit will need to be installed. Some terminals may just

require the locking tang on the terminal be reformed so it

will catch the appropriate step in the housing.

Immediately behind the connectors is another potential

failure area. This is increased if the wires are flexed or

sharply kinked. Moving the wires from side to side may

produce intermittent contact and locate the general area

of failure.

Corrosion of the terminals is possible as the machine

ages. In some cases simply disconnecting and

reconnecting a connector will solve a poor connection

problem. Heavy corrosion of terminals may occur since

the machine is exposed to or stored with fertilizer of

other corrosive products. This will require replacement of

the affected terminals to provide reliable connections

over a long period of time.

In troubleshooting a new machine or an electrical

system that has never functioned correctly, check for the

possibility that wires in the connector may be crossed or

that wires in the connector may be inserted in an

incorrect terminal where no continuity between

harnesses exists. Wire colors, functions and terminal

numbers (on numbered connectors) are listed in the

operator’s service manual under Electrical Circuits.

Wires that have been exposed to oil or sunlight may

require some of the harness covering to be removed to

aid in identifying the correct color.

General Information

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TOOLS

FIG. 1: The basic tool needed to troubleshoot the

electrical system is a portable digital

voltmeter-ohmmeter (otherwise known as a volt-ohm

meter, DVOM, or multimeter). A volt-ohm meter is not

expensive or complicated when purchasing a volt-ohm

meter, it is useful to have a resistance range with scale

to be able to check low values or resistance on

solenoids or clutch coils. Refer to the instructions

accompanying your volt-ohm meter for operating

procedures.

Today’s electronics will run variable voltages. Just

because the machine has 12 volt batteries does not

mean the system is running on 12 volts. Most machines

will have 12 volt circuits, 8 volt circuits and 5 volt

circuits. With different voltages being used a test light

will be useless, the only way to test a circuit will be with

a volt meter and ohm meter.

A volt meter should be used to do all electrical testing

and troubleshooting. Remember the circuit must be

fully connected and operated to get proper test results.

You should be looking for voltage drops to determine

where the problems are.

An Ohm meter should not be used to check a circuit

unless a volt meter cannot be used for some reason.

The ohm meter should only be used when checking

components or circuits that have a specified resistance.

An example would be a solenoid that may have

specified resistance of 7 - 0 ohms. An ohm meter is the

proper tool to be used.

Electrical connections and wiring are available to repair

the wiring harnesses on the machines. Also available,

are the connector housings to replace nearly every one

used on the machine. All are sold in pairs and the

molded style connections are supplied with wire leads

for splicing into the existing circuits.

FIG. 1

Q000069S

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General Information

GENERAL TESTING PROCEDURES

Visual Inspection

Carefully inspect the complete wiring harness for

damage. Check for loose or broken wires. Make sure

the connect terminals are fully seated and locked in the

connector. Insure that the terminals are clean and not

damaged.

Continuity Check

A continuity check is a test used to find whether a circuit

is complete. The circuit can be a single wire, a single

component or a combination of wires and components.

A circuit that has continuity is complete and current can

flow through the circuit. A circuit that does not have

continuity has break in the circuit that will not let current

flow through the circuit. An open can be caused by a

broken wire, a loose connection, dirty contacts in a

switch or connector or any other condition that keeps the

circuit from being complete. Visually check for these

conditions before doing a continuity check for these

common causes of open circuits are loose or dirty

connections and broken wires.

An open that comes in contact with a ground connection

such as the mainframe is called a short circuit to ground.

A continuity check is used to test a circuit that is not

connected to a power supply. To check a circuit that is

connected to a power supply, do a voltage check or

disconnect the circuit from the power supply and do

continuity check.

NOTE: Connecting an instrument for checking

continuity to a circuit that is connected to a

power supply can damage the instrument.

Hook your multimeter into the circuit and you will get an

ohm reading, if the circuit is complete.

Most digital multimeters have a setting for checking

continuity. This setting includes an alarm on most

multimeters. When the circuit being tested has continuity

(is complete) the indication will be zero and the alarm will

sound. If the multimeter has this type of setting, it is best

to use this setting for checking continuity. On most digital

multimeters, the resistance value will not be correct

when using the setting. To check resistance you must

use the ohms setting.

Voltage Check

A voltage check is a test used to measure the amount of

voltage in the circuit. The voltage check also determines

of a circuit has continuity.

A voltage check is used to test a circuit that is connected

to a power supply. To check a circuit that is not

connected to a power supply, do a continuity check.

Adjust the multimeter to indicate volts DC and, if

necessary, the correct range. Connect the (+) red lead of

the multimeter to the circuit and (-) black lead to ground.

If the multimeter does not indicate any voltage, there is

an open in the circuit or battery is completely

discharged.

If the multimeter indicates a negative (-) reading, make

sure the test leads are not reversed. Also make sure the

wires in the circuit being tested are connected correctly.

If the multimeter indicates voltage, compare the reading

to the voltage specified in the test.

If the test specifies a reading of system voltage, the

multimeter must indicate 10,8 to 16,8 volts. System

voltage is the amount of voltage in the battery which is

normally 13,8 volts.

NOTE: The system voltage can be several volts

different with the engine running or engine not

running. Unless specified, use the system

voltage for engine not running.

If the voltage reading is not correct, check the condition

of the batteries and the charging system.

Testing for Open Circuits

Test for an open circuit by folding the harness in half so

that two connectors are side by side. Test for continuity

through each wire using a digital multimeter. Use wire

colors or connectors pin identification numbers to

identify the wires at each and of the harness. If the

harness is not easily folded in half because of being

strapped down, connect two pins together at one

connector with a jumper wire. Test for continuity through

the wires at the other connector. Repeat this process by

moving the jumper wire as needed until all wires are

checked.

Finding a Break in an Open Circuit

Using a digital multimeter set to the ohms scale, connect

one probe to each end of the broken wire. Move along

the length of the harness, flexing the harness by hand,

while watching the multimeter. Any change on the

ohmmeter indicates the damaged area has been

located. If the damage cannot be located, find the

approximate middle of the harness length. Carefully cut

the outer jacket of the harness to reach the wire to be

tested. Insert a needle or pin through the wire insulation

and connect the meter to the needle or pin. Test for

continuity between the middle and each end of the wire.

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General Information

Testing for Short Circuits

A short circuit is defined as an unintended, low

resistance current path. This means that the current is

taking a shorter path than it was intended in the original

circuit. This could be a result of two or more wires

rubbing together (copper to copper) or a wire rubbing the

system ground (copper to iron).

Disconnect the harness at both ands. Using a digital

multimeter set to the ohms scale, and test for continuity

between the wires. To accomplish this, at one of the

harness connectors, test for continuity between pins as

follows:

By progressively moving through the pin count, no

combination of two conductors is missed. Continuity

should not be found between any wires or ground unless

shown on the wiring schematic.

NOTE: If continuity is found, the wires are shorted.

Testing for High Resistance

A high resistance circuit is defined as an unintended

resistance to current flow. This means that the circuit

must overcome more resistance than normally found in

the circuit. This could be caused by corroded connectors

or wires or a wire in the circuit that is nearly pinched to

breaking. This may cause the circuit to work erratically or

not at all. If the circuit may or may not indicate the proper

resistance and/or voltage level. A high resistance circuit

can generally only be tested when the circuit is under a

load (i.e. solenoid activated, control module resetting,

etc.)

To properly test for high resistance circuit, the digital

multimeter (set to the volt scale) has to be used to test

the complete circuit when the machine is operating.

Connect the (+) lead to the wire and the (-) lead to

ground to measure the voltage on the wire. If a high

resistance circuit is present, the voltage recorded when

operating the circuit will be lower than specifications.

Finding a High Resistance Circuit

A digital multimeter is used (set to the volts scale) to test

for a high resistance circuit. Connect the (+) lead to the

wire and the (-) lead to ground to measure the voltage

on the wire. The multimeter is placed in the circuit in this

manner so that it becomes a parallel path for the circuit.

The completed circuit voltage (as shown on the

multimeter) is then checked between segments of the

circuit. The problem area has been located when the

voltage changes noticeably on a segment being

checked.

Fuse Testing

To test a fuse pull the fuse from the slot and visually

inspect for broken pins, corroded contact and a broken

connection internally. If any of the above symptoms are

found, replace fuse. If none of the symptoms are found,

test for continuity by connecting a multimeter (set to

ohms) across the ends of the fuse. For a good fuse the

reading should be zero ohms. If the reading is blank or a

very high number (>5000 ohms), the fuse is bad.

Relay Testing

To test a black cube relay pull the relay out of the slot it is

located in. Visually inspect for broken pins or corroded

contacts. Connect power to pin 86. A click should be

heard every time you ground pin 85. The click means

the relay is good and can be reused. If no click is heard,

find a known good relay and test it. If it tests good,

replace the old relay with a good relay.

To test a black cube relay pull the relay out of the slot it is

located in. Visually inspect for broken pins or corroded

contacts. Connect power to pin 1. A click should be

heard every time you ground pin 2. The click means the

relay is good and can be reused. If no click is heard, find

a known good relay and test it. If it tests good, replace

the old relay with a good relay.

Diode Testing

Using the multimeter set to the ohm scale check the

diode for continuity by placing the leads across the diode

and then reverses the leads across the diode. In one

direction the ohmmeter should shown an open circuit

(blank display). With the leads reversed the display

should indicate a 0,6 to 0,9 ohms resistance reading.

In the multimeter does not read differently, the diode is

open or shorted and passes current in both directions.

Using the multimeter set to the diode scale on a good

diode the meter will beep when the leads are placed

across the diode. When the leads are switched, the

multimeter will not beep.

IMPORTANT: It is important that the replacement diode

be installed in the same direction as the one

which was removed. If not, other parts of

machine may be damaged.

1 to gnd

2 to gnd

3 to gnd

4 to gnd

ect

1 to 2

2 to 3

3 to 4

4 to 5

ect

1 to 3

2 to 4

3 to 5

4 to 6

ect

1 to 4

2 to 5

3 to 6

4 to 7

ect

1 to 5

2 to 6

3 to 7

4 to 8

ect

ect

ect

ect

ect

ect