MTD 148-802-000 Owner's Manual page 18

TROUBLE SHOOTING CHA RT FOR ELECTRIC START MODELS
TROUBLE
LOOK FOR
Engine will not
crank
Battery installed incor¬
rectly
Blown fuse or circuit
breaker
Mechanical failure
(Wires and switches)
Engine cranks
but wili not start
The battery mus t be installed with the negative terminal, identified at the terminal post by (Neg, N
or -), groundec. The positive terminal (Pos, P or +) attaches to the large cable from the solenoid.
The small red wire from the fuse holder or circuit breaker is also attached to the positive terminal.
Replace fuse wf h TVs amp. fuse % x VA" Ig. Circuit breaker will reset itself when it cools off. Fuses
or circuit breakers seldom open or fail without a reason. The problem must be corrected. Check for
loose connections in the fuse holder. Replace fuse holder if necessary. A dead short may be in the
cranking or cha ging circuit where the insulation may have rubbed through and exposed the bare
wire. Replace tfe wire or repair with electrician's tape if the wire strands have not been damaged.
Note: Look for i wire pinched between body panels, burned by the exhaust pipe or muffler or rubbed
against a moving part.
Use a hydromet jr to check the condition of the battery. The Specific Gravity (s.g.) should be 1.265
at SCF. (1.215 >.g. minimum needed for cranking engine). The reason for the battery failing must
be determined. 1) Defective battery. Battery will not accept or hold a full charge. (2) Short circuit.
Check for grounded wire. (3) Charging system not working.
The charging system is an alternator located under the flywheel. It is unregulated and rated 3 amp.
at 3600 r.p.m. diode (rectifier) is located in the output lead just before the wire harness plug on
the engine side
Diode
Shrink
Tube
To Alternator
0
;=
3 AMP DC
(Batt.)
y 7 AMP AC
^ (Lamps)
Black
Wire
Polarized
Plug
Throttle or choke not in
starting position
No spark to spark plug
The diode chan )es A.C. to D.C. to charge the battery. A bad diode can either fail to charge the bat¬
tery or discharg s the battery if the alternator is shorted as well as the diode. To test; (1) Disconnect
charger lead from the battery (small red wire). (2) Connect 12 V small test lamp between the 3 amp.
D.C. charge lead and the positive terminal of the battery. (3) With the engine off, the lamp should
not light. If it dees, the diode and possibly the alternator should be replaced. (4) Start the engine.
The lamp should light. If it does not, the alternator (stator) or lead wire is bad and should be replaced.
The interlock system includes two mechanical activated switches which are wired in series in the
circuit used to (inergize the starter solenoid. While testing the interlock system, you will make the
mower tempora ily unsafe by permitting the engine to be started with the blade and clutch engaged.
WARNING: Wh le testing, disengage the clutch, shut off the blade control, set the parking brake and
place the gear s hift lever in neutral. Attach a wire (minimum 18 gauge) to the positive terminal of the
battery and touc n the other end to the small terminal on the solenoid. If the engine does not crank: (1)
There is a loose connection or poor ground. (2) The solenoid may be bad. The solenoid can be checked
by using a heav t wire (#8 gauge minimum) and jumping between the two large terminals. If the engine
cranks, the soU noid is bad. (3) If the engine does not crank when you jump the solenoid, have the
starter motor tested by an authorized engine dealer. If the engine does crank, the problem is with
one of the safet t switches, ignition switch or the wire between the fuse holder (or circuit breaker) and
the small terminal on the solenoid. Note: Look for a poor connection at the switches or a defective
switch. Replace^ if necessary.
Check owner's guide for correct position for throttle control and choke for starting.
Spark plug lead disconnected. Connect lead. Hold spark plug lead away from engine block about
1/8". Crank enoine. There should be a spark. If not, have engine repaired at authorized engine ser¬
vice dealer.
Faulty spark pU g. To test, remove spark plug. Attach spark plug lead to spark plug. Ground the spark
plug body agai ist the engine block. Crank the engine. The spark plug should fire at the electrode.
Replace if it dees not.
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