PREVOST H 2018 Series, Operator'S Manual

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2 APPENDIX B – Troubleshooting Multiplex
Problem/Symptom Probable Causes Actions
Many secondary functions
(not essential for driving)
not functioning (interior
lighting, driver's area
lighting, wiper speed 2
and intermittent).
Marker lights and
clearance lights are
turned ON when setting
ignition to the ON
position.
The MCM module does not
receive 24 V power.
The DL0 (BBUS MUX)
network is not working. It
could be caused by a short
on the network, an open
circuit, a problem with the
MCM or the MCM being
disconnected from the
network.
1. Check / reset circuit breaker CB6.
Check / replace fuse F1
2. Operate in limp-home mode by
starting the vehicle from the engine
compartment (REAR START). All
functions essential to drive are
available
To close and lock the door, pull the door
manually up to its closed position and it
will lock by itself. The door opening button
is still functioning
No temperature control in
the passenger area
Passenger temperature
display indicates two
dashes "--"
Problem with the
temperature sensor located
in the evaporator
compartment air intake or the
sensor wiring Instruct the driver to manually control the
temperature by playing with the
passenger set point. Set above 22°C
(72°F) to heat and below 22° C (72°F) to
cool
Entrance door does not
open nor close using the
control buttons
Defroster fan not
functioning
Windshield wipers not
functioning in speed 1 or
intermittent Module AE47 is not powered
or is faulty 1. Check the SYSTEM DIAGNOSTIC
menu of Driver Information Display
(DID). Select FAULT DIAGNOSTIC
and ELECTRICAL SYSTEM. The
message “No Response ModA47,
Active” indicates a power problem on
the module. (A DL0 (BBUS MUX)
network problem would show the
same message but doesn't produce
these symptoms).
2. Check / reset circuit breaker CB1
3. Check / replace fuse F45
4. Probe gray connector on module to
see if it is powered.
5. Use the air release valves near the
entrance door and in the front service
compartment to lock / unlock the door
Windshield wipers not
functioning in speed 1 or
intermittent No power on R27 Check CB48 (VECF)
HVAC condenser fans not
functioning in speed 1 Circuit breaker CB7 tripped Check / reset circuit breaker CB7
HVAC condenser fans not
functioning in speed 2 Circuit breaker CB7 tripped Check / reset circuit breaker CB7
Check / replace fuse F135