SECTION 06: ELECTRICAL
40
DOB 2490-2789 | X3-45 Commuter PA1605 Maintenance Manual (Final Version) – Sec 06 revised June 2017
5.1
ALTERNATOR PERIODIC INSPECTION
When both alternators are not
charging, the
charging system
warning light
illuminates. This
telltale will not illuminate if only one
alternator is defective. However, a
single defective alternator can be
identified using the back-probing
method described below.
charging
system
warning
light
Maintenance
Alternator Periodic Inspection
Check that both alternators operate normally
using back-probing method described at
paragraph 5.1.1. Perform at the intervals
specified by the Lubrication And Servicing
Schedule in Section 24A.
5.1.1 Identifying a Single Defective Alternator
This method consists in back-probing specific
pins on J1 connector, Multiplex Module A49.
Prerequisite conditions:
a) Engine
running;
b) Parking brake applied.
On connector J1 of multiplex module A49, back-
probe pin 8 (A49 J1:8) and a good ground (use
ground stud in the compartment). Repeat for pin
9 (A49 J1:9).
Lower alternator: pin 8
Upper alternator: pin 9
1.
Back-probe pin 8 (A49 J1:8).
If multimeter reads 1-2 volts, the
lower
alternator is defective;
If multimeter reads 12 volts, you have
an open circuit;
If multimeter reads 26 volts or greater,
the
lower
alternator operates normally.
2.
Back-probe pin 9 (A49 J1:9).
If multimeter reads 1-2 volts, the
upper
alternator is defective;
If multimeter reads 12 volts, you have
an open circuit;
If multimeter reads 26 volts or greater,
the
upper
alternator operates normally.
Note
Validation
Confirm back-probing results before removing
the defective alternator. In fact, the
connectors on the alternators may have been
interchanged by mistake.
1. Stop the engine and then disconnect the
suspected defective alternator.
2. Start the engine. Back-probe the pin on
the alternator known to be in good
working condition.
3. If multimeter reads 1-2 volts, then this
alternator is defective. A misconnection of
the alternators exists. Check the
regulators connectors.
5.2
ALTERNATOR DRIVE BELT
Removal
1. Insert a ½
″
socket drive wrench into the
automatic belt tensioner opening (Figure
38).
2. Twist the tensioning arm to slacken belt.
3. Remove
belt.
FIGURE 38: ½
″
SOCKET DRIVE WRENCH
Note
Belts specifications may vary. For proper belt
selection, always consult your vehicle coach
final record.
Installation
