PREVOST H3-45 VIP Owner's Manual page 220

B-8 Multiplex Troubleshooting
Problem / Symptom
The vehicle is parked and
the electrical horn
activated 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
No backlighting in
instrument cluster
The radiator/CAC electric
fans do not function and the
engine is overheating
Probable Causes
Short- circuited fire sensor or
is defective sensor
The multiplex
protected in current by an
internal "soft fuse". When an
output is shorted, it turns OFF
and stays OFF until the "soft
fuse" is reset
the Circuit breaker CB10 is tripped
or fuse F10/F29 blown
PA-1638 Owner's Manual X3-45 VIP
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
outputs are turn the ignition key to the OFF position and
turn to the ON position again. This resets all
"soft fuses"
Check circuit breaker CB2, CB10
Check / replace fuse F10, F29
Check / replace relay R22, R23
You can manually engage the radiator/CAC
fans half-speed (50%) or full speed (100%).
1. On the Driver Information Display,
select DIAGNOSTICS menu. Select
VEHICLE TESTS submenu and then
FORCE RADIATOR FAN SPEED
50% or FORCE RADIATOR FAN
SPEED 100%.
2. The DID status line will show TEST to
confirm the forced activation of the
radiator fans. To cancel, turn the
ignition switch to the OFF position or
press
TERMINATE TESTS & FORCED
STATES submenu and then press
ENTER
disappear from the DID status line.
Actions
ESCAPE button,
button twice. TEST
select
will