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Troubleshooting Mower Safety Start Switches

SERVICE

BULLETIN

118

INFORMATIONAL

SUBJECT: Safety Switches Installed in Starter and/or Ignition Circuit

MODELS OR TYPES AFFECTED: All Tecumseh Engines

Because of safety regulations for lawn and garden equipment, most manufacturers are incorporating some type of safety switch in their designs to prevent the operator from starting the engine if the unit is in gear and/or the mower blade or other attachment is engaged.

Methods and circuitry vary from manufacturer to manufacturer but the following are basic methods most usually found.

1.A switch installed so the transmission or transaxle must be in a neutral position before the engine can be started. This can be wired in the starter circuit or the ignition circuit.

2.In addition to the neutral, an additional switch is added to the cutting or other attachment control lever so the engine cannot be started with the mower blade or other attachment engaged. This switch can be in the same circuits as a neutral position switch.

3.A switch is installed on the clutch pedal which will not allow the operator to start engine unless clutch pedal is in a disengaged position. This switch would generally be wired in the starter circuit.

REMEMBER Tecumseh does not supply safety switches or assume any responsibility for their proper adjustment or operation. The purpose of this bulletin is merely to alert you that a safety switch may not be functioning properly resulting in the engine not starting.

To determine whether the problem is in the engine itself, refer to the following Troubleshooting Chart.

TROUBLESHOOTING SAFETY-START SWITCHES

 

FAILURE

CHECK

 

 

 

 

(Electric Start Engine)

Disconnect ignition cut-off wire at the engine. Crank engine.

 

Electric starter cranks but no spark at

If spark at spark plug, ignition switch or safety switch is

 

spark plug.

inoperative. If no spark, check ignition module or magneto.

 

 

See Mechanic's Manual.

 

(Non-Electric Start Engine)

Disconnect ignition cut-off wire at the engine. Crank engine.

 

 

If spark, check ignition switch and safety switch. If no spark,

 

 

check ignition module or magneto. See Mechanic's Manual.

 

 

 

 

Electric starter does not crank engine

Remove wire from starter. Use a jumper battery and cables

 

 

and attach directly to starter. Attach the negative clamp to

 

 

an engine ground as the last connection to prevent sparks at

 

 

the battery. If starter cranks engine, the starter is okay;

 

 

check solenoid, starter switches and safety switches.

ALWAYS CHECK WIRES FOR POOR CONNECTIONS, CUTS OR BREAKS BEFORE

CONDEMNING A PART

IMPORTANT - TO AVOID ANY POSSIBLE PERSONAL LIABILITY

In the event you are not able to repair or replace a faulty safety switch, do not by-pass or remove it from circuit. Rather, fully advise the owner of the situation and direct him to contact the party from whom the unit was purchased for proper repair or replacement.



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