SECTION 06: ELECTRICAL
DOB 2490-2789 | X3-45 Commuter PA1605 Maintenance Manual (Final Version) – Sec 06 revised June 2017
5
1. GENERAL
DESCRIPTION
These x3-45 coaches use a dual voltage system
to obtain two different voltages (12 and 24 volts)
for various electrical controls and accessories.
The main power source incorporates four
“odyssey” group 31 commercial batteries
connected in parallel-series. All batteries are
kept uniformly charged by means of a 100 amp
battery equalizer (standard), giving a maximum
possible output supply of 100 amps on the 12
volt system. Both the 12 and 24 volt systems are
controlled through individual main battery relays.
Two 28 volt self-regulated alternators are
installed and are belt driven from the engine,
and can be reached through the engine
compartment doors.
1.1 WIRING
DIAGRAMS
A master wiring diagram of the electric circuits,
covering standard and optional accessories and
systems, is located in the technical publications
box. Usually, a separate wiring diagram page is
provided for each major function or system. In
some cases, more than one circuit may appear
on one wiring diagram page; when this occurs,
each circuit covered in this page is listed in the
wiring diagram index. Moreover, a circuit may
appear on several pages; in such case, the
number(s) at the extremity of the diagram title
will indicate the sheet reference number. Refer
to the "wiring diagram index" to ensure that the
correct diagram is being used to trace the circuit
in question. In addition to the major functions
page reference, the wiring diagram index
contains the following information pages.
The multiplex output / input list,
Multiplex error message list,
The arrangement-harness drawing showing
the harness arrangement and harness
numbers on the vehicle,
Glossary,
Circuit number listing,
Circuit breaker code,
Connector
code,
Diode number code,
Resistor number code,
Fuse
code,
Relay
Code.
1.1.1 Using
Wiring
Diagrams
Three methods are used to
"work"
with electric
wiring diagrams.
Situation:
you have identified the defective part
(breaker, diode, relay, etc.), and you wish to
locate its corresponding circuit.
Problem:
circuit breaker cb13 is released (open
circuit) and you don't know which circuit is
affected.
a) Refer to wiring diagram index, and look for
"circuit breaker code"
. You find that the
circuit breaker list is on page f.
b) At item cb13, you will find the location, the
Prevost number, the breaker function, the
breaker amp rating and the page on which
to find the corresponding diagram.
c) Refer to page 3.1.
d) When you have located cb13, follow the
wiring up to the end and find the diagram
page number and function on which the
circuit continues.
Situation:
you have a problem with a specific
system and you want to find the corresponding
diagram.
Problem:
the last three (3) speakers on the R.H.
side of vehicle are inoperative and you must
trace the electric circuit.
a) Refer to wiring diagram index and look for
“sound system”.
b) You will find on page 35.2 the components
as well as the electric wiring, thus providing
you with a complete understanding of this
circuit.
Situation:
using the driver information display
(DID), you check on arrival if there are active
errors in the vehicle electrical system. With the
diagnostics
menu, highlight
fault diagnostics
,
highlight
electrical system
to request a
diagnostic of the electrical system and then
press the enter key. If applicable, the DID shows
the fault messages or fault codes recorded.
When more than one fault is recorded, an arrow
pointing down appears on the right of the
display. Use the down button to see all the fault
messages.
Problem:
DID displays the fault "elec. horn
sw61 sw62; shorted to ground" as being active.
a) Refer to wiring diagram index, and look for
"multiplexed device index"
, pages b1-b8.
