PREVOST H 2018 Series, Operator'S Manual

Page: 237 / 258

APPENDIX B – Troubleshooting Multiplex 1
Problem/Symptom Probable Causes Actions
Vehicle does not Start The Engine Stop pushbutton
located on the rear start
panel is depressed
Main electrical shut-off switch
is in the OFF position
1. Twist and pull the Engine Stop
pushbutton to place it in normal
operating position, check that the
main electrical shut-off switch is in the
ON position and retry cranking from
the ignition switch
2. Start the vehicle from the engine
compartment using the rear start
button
DL0 (BBUS MUX) network
problem (Multiplex)
Module AE52 not powered or
is defective
Engine ECM does not
receive the ignition signal
Engine ECM is not powered
If the vehicle does not start from the rear:
1. Verify that module AE52 is powered:
a) Check the SYSTEM DIAGNOSTIC
menu of Driver Information Display
(DID). Select FAULT DIAGNOSTIC
and ELECTRICAL SYSTEM. The
message “No Response ModA52,
Active”, indicates a power problem
on the module or a DL0 (BBUS
MUX) network problem.
b) Check / reset circuit breaker CB5
c) Check / replace fuse F65
d) Probe gray connector on module to
see if it is powered.
2. Verify that the engine ECM is
powered and gets the ignition signal
a) Check / reset circuit breaker CB8
Check / replace fuse F74
b) Check / reset circuit breaker CB2
Check / replace fuse F78
None of the Multiplexed
functions are operating,
including the basic limp-
home functions (door
opening, flashers, wipers
in speed 1)
“FLIP REAR BREAKER
TO INITIATE I/O
MODULES
PROGRAMMING” pop-up
message appears in the
DID
Note: The sunshades are
still functioning since
these are not multiplexed
The program version in the
MCM is different than the
program in the I/O modules
and the MCM is forcing all
I/O modules to stay inactive
1. Engage the auto-programming of the
I/O modules: Turn the ignition key to
the ON position, trip and reset circuit
breaker CB6.
2. The DID indicates "MUX
AUTOPROGRAMMING I/O MODULE
PLEASE WAIT" until the
reprogramming is complete.