Mountfield T38M-SD ride-on won't start (no spark)

[Feathers_McGraw]

Hi everyone,

My Mountfield T38M-SD ride-on mower won't start, I've had a go at fixing it myself but I've run out of ideas and would appreciate some advice!

I can't get a spark.

I've tested the battery with a multimeter and it appears to be fully charged (voltage is 12.7V).

The spark plug looks OK (fairly clean, no wear), and I've replaced it anyway just to be sure. If I hold the plug against the engine I don't get a spark with either the new or old plug.

I tested the resistance of the ignition coil using a multimeter and it seemed high going by what I've read online (11.91kohm), so I bought a new genuine part and replaced it. I still can't get a spark.

I don't know how much voltage you would expect going into the ignition coil when the key is turned but I get 0V DC (should it be 12V?).

The mower has some safety features built in so it won't start if certain criteria aren't met. There is a person in the seat, the mower is in neutral and the brake/clutch pedal is all the way down.

I am wondering if one of the safety switches (e.g. the seat sensor) could be faulty and preventing power from being delivered to the ignition system.

Could it be this, or are there other things I should be checking first?

Edit: I checked the fuses too, both the 10A and 25A fuses are fine (again, I replaced them just to be sure)

 

[bertsmobile1]

Take the small wire off the coil and try again.
The small wire grounds out the coil preventing it from sparking which is how turning the mower off works.
Don't throw out the old coil.
The secondary windings almost never go bad so resistance measurement is what You tube monkeys do to prove they are at a higher evolutionary level than just learning how to shave the hair from their palms.
The coil has a trigger in the primary windings which is connected to the thin wire and this is a micro chip so resistance readings are meaningless.

If you get a spark with the wire disconnected then the mower has a wiring problem.
With the key switch on the wire is open circuit
With the key switch off the wire is ground ( or earth if you like )
So measure the resistance between this wire and the mower.
If it is ground and the key is on, follow it back till you find where it goes to ground and that switch ( or wire ) is faulty.
Remember the brake must be on and the blades must be off.

I can not get Mountfield wiring diagrams down here so this is s far as I can take you.