Assembly Installation Instruction Manual
A9-305
Mid-to-High Frequency EMC
Filter Assembly
Installation Instructions
Page 1 of 2
II1B
Figure 1 - Filter Assembly Location on Alternator
(choose one of five locations)
Drive end housing cover plate
Control unit cover
1
2
3
4
5
A9-305 Filter Assembly is designed only to
reduce electromagnetic interference (EMI)
from CEN alternator/regulator to acceptable
levels as defined by Society of Automotive
Engineers (SAE) specification J1113/41. This
device will NOT reduce EMI from sources
such as vehicle digital systems, wireless links,
digital devices, antennas, poor cable routing
practice, and other electrical/electronic
devices that cause EMI. If EMI continues after
installing A9-305 per these instructions,
consult an electromagnetic compliance
(EMC) specialist to determine EMI source.
NOTICE
2. Install filter assembly to be connected to
B+ terminal on alternator:
a. Disconnect vehicle battery master switch or
vehicle battery cables.
b. To install unit directly on alternator:
1) Remove and discard two short screws from
selected location on alternator (see Figure 1).
2) Make sure ring terminals on filter assembly
are clean and have good contact surface.
Place filter assembly on alternator.
3) Use one new screw and lockwasher supplied
i n k i t t o s e c u r e r i n g t e r m i n a l o f g r e e n g r o u n d
wire in closest mounting hole in alternator.
Insert second screw and lockwasher in
remaining mounting hole.
4) Torque both screws to 2.3Nm / 20 lb.in.
c. To install unit in location other than alternator:
1) Set unit in mounting location. Secure green
ground wire from unit to grounded surface,
using one mounting hole in unit. Use second
mounting hole to finish securing unit to
mounting location.
d. Connect B+ connecting wire from unit to alter-
nator B+ terminal, splicing B+ wire length if
required from step 1, as shown in Figure 2.
e. Reconnect vehicle battery master switch or
vehicle battery cables.
f. Operate engine and check alternator output.
Only on units
with F+ terminal
Flat washer
Lock washer
B+ Terminal Bolt
(torque varies with
alternator model)
Terminal from
vehicle battery B+ cable
B+ connecting wire
from A9-305
Figure 2 - Alternator B+ Terminal Stacking Order
To connect filter assembly to B+ terminal
on alternator, see page 1.
To connect filter assembly to power source
of other affected electrical/electronic
components, see page 2.
1. Before connecting filter assembly to B+
terminal on alternator, determine where to
install unit:
For alternators with front housings that look
like Figure 1: Choose location on alternator best
suited for vehicle conditions to install filter
assembly. B+ connecting wire as provided on
unit is 12 inches long.
For other alternators: Select location for filter
within 12 inches of B+ terminal on alternator.
If location within 12 inches is not practical,
B+ connecting wire can be spliced to increase
d i s t a n c e u p t o 2 f e e t f r o m a l t e r n a t o r B + t e r m i n a l .
Increased wire length reduces filter effectiveness.
F+ terminal
not on all units
B+ connecting
wire
Green ground
wire
NOTICE
EMC filter can be installed either
at power supply of the affected
component or at the B+ terminal
on the alternator.