John Deere 318 - Manual (Page 328)

3e
Ignition Coil Test:
Secondary
Windings—
For Machines
(S.N. —420000)
Key switch OFF.
Disconnect all wires
from ignition coil.
M77938 -UN-19JAN95
Using a ohmmeter,
measure resistance of
secondary windings at
spark plug wire
terminals (A).
Resistance should be
12.6—15.4 K-ohms
when temperature of
coil is approximately
20˚C (68˚F).
RESISTANCE NOT
OK: Replace coil, then
GO TO
Æ
, Group 05.
3f
Ignition Circuit
Test—For
Machines
(S.N. 420001— )
Disconnect spark plug
wires and remove spark
plugs.
Connect a spark tester
to each of the spark
plug wires.
M45243 -UN-12JAN90
IMPORTANT: Do not
touch the negative
coil terminal with the
jumper wire. Battery
voltage applied to the
negative coil terminal
will damage the
ignition control
module.
NOTE: Terminal (A) is
smaller in diameter of
the two posts.
Connect a jumper wire
from positive (+) battery
terminal to positive (+)
coil terminal (A).
Crank engine and
check for spark.
SPARK: White wire to
3-pin engine connector
is open or 3-pin engine
connector is faulty.
Repair or replace as
necessary, then GO TO
Æ
, Group 05.
NO SPARK: GO TO
3g
MX,159024025,46-19-16MAY95
MX,159024025,47-19-16MAY95
Electrical System Diagnosis/Ignition Circuit Tests
TM1590 (17MAY95)
240-20-16
316, 318 & 420 Lawn and Garden Tractors
020895
240
20
16