Testing Circuits; Wire Sizes And Colors; Wire Identification - PREVOST H3-41 Maintenance Manual

SECTION 06: ELECTRICAL
a) Refer to wiring diagram index, and look for
"Multiplexed Device Index", pages B1-B8.
b) In first column DEVICE ID, look for device
SW63.
c) At device SW63, find the fault message, the
minimum condition to activate, other inputs
involved in logic, the multiplex module
related to switch 63, the connector and pin
number on the module and the page on
which to find the corresponding diagram.
d) Once the problem corrected, the DID still
shows the fault as being active. You have to
leave the VIEW ACTIVE FAULTS menu,
wait approximately 20 to 30 seconds and
then return to VIEW ACTIVE FAULTS to
request a new diagnostic of the electrical
system from the MCM. The DID should
display the fault as being inactive.
2.2

TESTING CIRCUITS

A careful study of the wiring diagrams should be
made to determine the source and flow of
current through each circuit. When a circuit is
thoroughly understood, a point-to-point check
can be made with the aid of the applicable wiring
diagrams. Any circuit can be tested for continuity
or short circuits with a multimeter or a suitable
voltmeter.
All electrical connections must always be kept
clean and adequately tight. Loose or corroded
connections can result in discharged batteries,
difficult starting, dim
functioning of other electric circuits. Inspect all
wiring connections at regular intervals. Make
sure knurled nuts on all amphenol-type plugs
are securely tightened. Knurled nuts on the
plastic amphenol-type connectors will click into a
detent when properly
connectors, who have the side locking tabs,
must have the locks latched in place to ensure a
proper electrical connection.
2.3

WIRE SIZES AND COLORS

Each wire in the electrical system has a specific
size as designated on the wiring diagram. When
replacing a wire, the correct size must be used.
Never replace a wire with one of a smaller size.
The vehicle electrical system is provided with
different voltages. The insulation on each wire is
distinctly colored in order to determine visually
the wiring voltage and to assist in making
16 PA1621 Maintenance Manual All Series | Revised Sept 2019
lights and improper
tightened. Line
connectors. The wires are color coded as
follows:
Yellow Data link High
Green Data link Low
Orange Connected to multiplex outputs
White Connected to multiplex inputs
Red 24 volt system
Yellow 12 volt system
Black grounded wire
Orange speakers (+) (Coaches Only)
speakers (-) (Coaches Only)
Brown
Grey spare wire
Black convolute tube
containing:
Black 120V ac system (live)
White 120V ac system (neutral)
Green 120V ac system (ground)
NOTE
Wires are identified at each 2-4 inch (5-10 cm)
intervals by a printed number.
2.4

WIRE IDENTIFICATION

Each wire on a diagram is patterned to assist in
tracing and testing
identification identifies the voltage reading or
network, the circuit identification and the basic
wire gauge.
with orange tape
circuits. The wire