John Deere 318 - Manual (Page 313)

ABOUT THIS GROUP
Always perform the system checkout procedures in
Group 05 BEFORE doing any tests in this group. The
step-by-step procedures in this group provide you
with the detailed diagnostic information you will need
to isolate a malfunction. Always start with the first
step and follow the sequence from left to right. Read
each step completely before performing the test.
Basic diagnostic equipment is used. It is assumed
that you are familiar with the machine and its
electrical components.
IMPORTANT: Before doing any testing, verify the
system ground circuits and test the
battery. All ground connections
must be clean and tight and the
battery fully charged.
Upon completing a test or adjustment, check to see
whether the problem is corrected by performing the
checkout procedure for that step in Group 05.
A
VERIFY SYSTEM GROUNDS
NOTE: For machines (S.N. —475000), the
ground wires for the PTO lamps, hour meter, and
TDC module (2-pin connector) terminate at the
right pedestal panel. Exterior components, such
as the PTO clutches and head and tail lights use
the tractor frame for ground.
For machines (S.N. 475001— ), all component
grounds terminate (spliced) inside the main
harness with one wire connecting to a single
ground point located where the battery negative
(—) cable connects to the engine block.
Key switch OFF.
M55069 -UN-09DEC89
M55070 -UN-09DEC89
NOTE: Machines
(S.N. —475000)
shown.
Verify the system
grounds using a
continuity tester or
ohmmeter. Check for
good continuity
between battery
negative (—) terminal
and the following:
Battery ground (A)
connection to engine.
Harness ground (B)
connection to right
pedestal panel;
(S.N. —475000) only.
NOT OK: Clean and
tighten ground
connections as
necessary.
OK: GO TO
B
B
BATTERY TESTS
NOTE: If problem is with starting circuit, perform
all battery tests. If problem is with other
components, perform battery tests only if starter
does not crank engine satisfactorily.
M78970 -UN-09MAY95
Check electrolyte level
in each cell of battery.
If low, add the proper
amount of electrolyte or
DISTILLED water.
Continued on next page
MX,159024025,1 -19-16MAY95
MX,159024025,2 -19-16MAY95
Group 20
Electrical System Diagnosis
TM1590 (17MAY95)
240-20-1
316, 318 & 420 Lawn and Garden Tractors
020895
240
20
1