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From: Jon on 19 Jun 2010 23:43
MTD Products, Inc. Model # 13am675g062 14.5hp Briggs & Stratton.

I lost the keys to this lawn tractor and ordered another ignition switch,
which had 5 terminals while the original had 6. I put it on anyway, turned
the key, heard a faint spark and nothing happened. Later I found the keys
to the old ignition switch, put it back on, turned the key and nothing
happened.


__ __
__ red green
red/black
__ __
yellow red/white
__
orange

The hash marks are terminals. The new ignition switch lacks the red/black.

With my meter I made a truth table for both of the switches.

old ignition switch

( \ ) OFF
red/black =| red/white
red/black = red
red/white = red
all others open

( | ) RUN
red/black = green
red/black = yellow
green = yellow
all others open

( / ) START
green = yellow
green = orange
yellow = orange
all others open

new ignition switch
( \ ) OFF
green = orange
all others open

( | ) RUN
red = red/white
all others open

( / ) START
yellow = red/white
yellow ~ red
all others open

where = means the two wires connect through the ignition switch, and ~ means
the connection is neither open nor closed but has some resistance.

Testing the wires on the plug that plugs into the ignition switch, none have
voltage. Red, green and yellow are all grounded. Orange is grounded too
when the clutch pedal is depressed. The tractor battery is 12 volts and
fully charged.

=====

I cut the red/white wire which left two ends. On the end that goes to the
ignition switch, I wired it directly to the positive terminal of the
battery.

I cut the yellow wire which left two ends. On the end that goes to the
ignition switch, I wired it directly to the solenoid coil.

I cut the orange wire and left the connection open.

I cut the green wire and left the connection open.

I left the red/black wire off and the connection open.

I didn't cut the red wire and left the connection closed.

====

When 12 volts goes to the red wire a relay clicks somewhere down in the
engine. I suspect it to be the engine kill relay, N.C. SPST.

====

by using a relay, the problem is solved..

12vdc = red/white
o
| /
| /
*-------o (/) o----*----- yellow ------o solenoid
| START |
| |
| (A) coil A
| |
| |
| -----
| ---
| / -
| /
*------o (|) o-----*------- red --------o engine on/off switch
| RUN |
| |
| -----
| ----- A contacts N.O.
| |
| |
*------------------*




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