SkyTrak 6036 Service Manual - Manual (Page 362)

Electrical System
9.10 Model 6036 Legacy
9.7 ELECTRICAL SYSTEM
TROUBLESHOOTING
9.7.1 Introduction
The electrical system produces, stores and distributes
electricity in the operation of the vehicle.
An engine-driven, 12-volt, 65-amp alternator, equipped
with an internal, solid-state voltage regulator, produces
electricity. Current from the alternator charges the battery
and powers electrical system components.
The battery provides power for starting the engine and
supplements the output of the alternator during periods of
peak demand.
The vehicle is equipped with two separate, but connected
wiring harnesses, an engine harness and a cab harness.
A multiple or “bulkhead” connector at the end of each
harness joins the two together.
Each wire within a harness has color-coded insulation
which is marked with a number to aid in identifying and
tracing each circuit and in making proper connections.
Fuses and relays are included with the cab harness to
help protect the electrical system and its components.
The main wiring diagrams in this section indicate
electrical circuits and components respective of their
approximate locations on the vehicle.
The information in this section has been developed from
the perspective that all wires are connected and routed
as they were when the vehicle left the factory. Take into
account any disconnected or rerouted wires before
beginning to diagnose a circuit. Refer to the wiring
diagrams to test circuits for continuity or for shorts using
a digital multimeter, analog multimeter, test light,
ohmmeter or low-reading voltmeter.
The text discusses each circuit and component, as well
as component function and replacement. Many of the
circuits have a separate diagram specific to that circuit’s
function which can be used for troubleshooting purposes.
Those same circuits also have their own troubleshooting
flow charts. Keep in mind that the various systems on the
vehicle include both electrical and hydraulic components.
What at first may appear to be an electrical problem, may
turn out to be a hydraulic problem.
Note: All of the main electrical schematics in this
section are shown in the OFF position. The individual
circuit diagrams are shown in the ON position.
9.7.2 Troubleshooting with a Digital
Multimeter (DMM)
IMPORTANT: Circuits which include any solid-state
control modules should only be tested with a ten
megohm or higher impedance digital multimeter or
damage could occur to the module.
A DMM should be used instead of a test lamp in order to
test for voltage in high impedance circuits. While a test
lamp shows whether voltage is present, a DMM indicates
how much voltage is present.
The ohmmeter function on a DMM shows how much
resistance exists between two points along a circuit. Low
resistance in a circuit means good continuity.
IMPORTANT: Disconnect the power feed from the
suspect circuit when measuring resistance with a DMM;
this prevents incorrect readings. DMM’s apply such a
small voltage to measure resistance that the presence of
voltages can upset a resistance reading.
Diodes and solid-state components in a circuit can cause
a DMM to display a false reading. To find out if a
component is affecting a measurement, take a reading
once, then reverse the leads and take a second reading.
If the readings differ, the solid-state component is
affecting the measurement.
The following are examples of the various methods of
connecting the DMM to the circuit to be tested:
• Backprobe both ends of the connector, and
either hold the leads in place while manipulating
the connector or tape the leads to the harness for
continuous monitoring while you perform other
operations or test-driving.
• Disconnect the harness at both ends of the
suspected circuit where it connects either to a
component or to other harnesses.