PREVOST X3-45 COACH 2018 Operator's Manual page 211

Appendix B - Troubleshooting Guide for Multiplex Vehicles
Problem/Symptom
HVAC condenser fans not
functioning in speed 1
Sound system not
functioning
Fire alarm telltale light
and audible alarm always
ON and there is no fire or
high temperature in the
engine compartment
The vehicle is parked and
the electrical horn is acti-
vated to indicate a fire in
the engine compartment
but there is no fire
A single light, a group of
LED lights or another
function of the vehicle is
not functioning
Probable Causes
or is faulty
Module AE54 is not powered
or is faulty
Circuit breaker CB11 tripped
Short-circuited fire sensor or
defective sensor
Short-circuited fire sensor or
defective sensor
Multiplex outputs are
protected in current by an
internal "soft-fuse". When an
output is shorted, it turns
OFF and stays OFF until the
PA1627 X3-45 Operator's Manual
Actions
3. Check the SYSTEM DIAGNOSTIC
menu of Driver Information Display
(DID). Select FAULT DIAGNOSTIC
and ELECTRICAL SYSTEM. The
message "No Response ModA54,
Active" indicates a power problem on
the module. (A CAN network problem
would show the same message but
doesn't produce this symptom).
4. Check / reset circuit breaker CB5
5. Check / replace fuse F135
6. Probe gray connector on module to
see if it is powered.
1. Check the SYSTEM DIAGNOSTIC
menu of Driver Information Display
(DID). Select FAULT DIAGNOSTIC
and ELECTRICAL SYSTEM. The
message "No Response ModA54,
Active" indicates a power problem on
the module. (A CAN network problem
would show the same message but
doesn't produce this symptom).
2. Check / reset circuit breaker CB5
3. Check / replace fuse F135
4. Check / replace fuse F141-F144
5. Probe gray connector on module to
see if it is powered.
1. Check CB11
2. Check / replace fuse F148, F200
Prior to start the vehicle, cycle the ignition
key to the ON position, OFF position and
then ON position again and then start the
vehicle. This will deactivate the fire alarm
function. This has to be repeated each
time the vehicle is re-started
Cycle the ignition key between the ON
and OFF position twice within 3 seconds.
This will deactivate the fire alarm function.
This has to be repeated each time the
vehicle is parked
Turn the ignition key to the OFF position
and turn to the ON position again. This
resets all "soft –fuses"
5