Multiplex Troubleshooting Table - PREVOST H3-41 Maintenance Manual

SECTION 06: ELECTRICAL
DL0 (BBUS MUX) wires are not like other common electrical wires.
Maintaining a proper wire twisting is important. The two yellow and green wires must be twisted
•
and in close contact all along the network to maintain the transmission line impedance.
A slack handmade twisting is not acceptable.
•
There should be no more than 50 mm (2 inches) without twist at the connection points.
•
We recommend replacing the DL0 (BBUS MUX) harnesses instead of trying to repair them.
7.3

MULTIPLEX TROUBLESHOOTING TABLE

Problem/Symptom
Vehicle does not Start
40 PA1621 Maintenance Manual All Series | Revised Sept 2019
Probable Causes
The Engine Stop pushbutton
located on the rear start
panel is depressed
Main electrical shut-off switch
is in the OFF position
DL0 (BBUS MUX) network
problem (Multiplex)
Module AE52 not powered or
is defective
Engine ECM does
receive the ignition signal
Engine ECM is not powered
Actions
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
If the vehicle does not start from the rear:
1. Verify that module AE52 is powered:
a) Check the DIAGNOSTICS menu of
Driver Information Display (DID).
Select VIEW ACTIVE FAULTS and
ELECTRICAL. The message "No
Response
indicates a power problem on the
module or a DL0 (BBUS MUX)
network problem.
not
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
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
ModA52, Active",
the engine ECM is