PREVOST H3-41 Maintenance Manual page 209

Problem/Symptom
Evaporator fan not
functioning
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
Probable Causes
Circuit breaker CB3 tripped
Module AE54 is not powered
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
PA1621 Maintenance Manual All Series | Revised Sept 2019
SECTION 06: ELECTRICAL
Actions
1. Check circuit breaker CB3
2. Check relay R12
3. Check the DIAGNOSTICS menu of
Driver Information
Select VIEW ACTIVE FAULTS and
ELECTRICAL. The message "No
Response ModA54, Active" indicates
a power problem on the module. (A
DL0 (BBUS MUX) 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 DIAGNOSTICS menu of
Driver Information
Select VIEW ACTIVE FAULTS and
ELECTRICAL. The message "No
Response ModA54, Active" indicates
a power problem on the module. (A
DL0 (BBUS MUX) 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
Display (DID).
Display (DID).
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