Disconnect the RED wire near the engine where it comes from the alternator. It may be in a connector with the ORANGE wire?
Also disconnect the BLUE wire at the Carb solenoid.

IF it STILL blows the fuse, either the RED AND/OR BLUE wire is shorted to ground.
OR the ignition switch is bad and shorting internally.

IF the RED wire blows the fuse ONLY when it is connected, your charge DIODE is most likely shorted.

One OTHER possibility is the ammeter is shorted to ground?
You can disconnect those 2 leads and jump them together to test that theory. I'm aware of that happening at least once, where an ammeter got moisture in it and shorted to the metal case.

Do you have a Volt-Ohm meter?

I read your first post again and have a different understanding.

IF the fuse is blowing when going to the ON position of the switch, but before cranking, then it would have to be the switch.
Reason-
1.-RED wire is always connected between battery and diode. Fuse would blow no matter what position ign. switch was in, if that wire or diode was shorted.
2. Engine runs. It wouldn't do that if Blue wire is grounded, since carb wouldn't pass fuel.

Are you sure the fuse isn't blown before you try to start?
It makes a big difference for trouble shooting.

http://www.managemyhome.com/mmh/lis_pdf/OWNM/L0710614.pdf

His battery/fused wire goes to B and then directly to the charge diode. NO switching.
His L only goes to the fuel solenoid.

Truong-
Lets start with my post- Thu, Jun 5, 08 at 14:59

Is the fuse blowing when you turn the key ON, or is it already blown when the key is OFF?

Truong Vu

Let's check the switch-
Remove switch-
With the OHM meter, put one lead on the B terminal.
In the OFF position, there should be NO continuity to ANY other terminal.
IN the ON and ON w/lights positions, there should be continuity to L ONLY.
In the START position, there should be continuity to L AND S ONLY.
Make sure there is NO continuity to terminals that shouldn't have it.
Use the "truth table" on the bottom of the schematic for reference.

I'll be near the computer, so let me know what happens (I have to go eat).
IF it's not the switch, we'll go to step 2.

I will try it tomorrow after work 4:00 PM , tonight I have some work has to be done. Thanks

Truong Vu

Truong Vu

Does the ammeter have a metal case./body?
With the key OFF, give the ammeter a good "thunk" with your palm.
Does it blow the fuse?
IF So, disconnect the leads and jumper them together.
IF that solves the problem, the ammeter is shorting when the needle moves.

Truong Vu

Unplug FUSE
Unplug RED wire at the Charge Diode by the alternator. (It MIGHT be in a connector with the ORANGE wire. IF So, disconnect both)
Unplug BLUE wire to Carb solenoid.

Connect ONE test lead to tractor ground.
Check (individually)
L terminal
B terminal
Neither should show continuity.

BTW, did you check B and L for continuity to Y?(ALL switch positions) Shouldn't be ANY.

Do you know how to check Diodes?

If it always blows on the restart, its probably the ignition switch.

I did not check B and L for contnuity to Y, will do it after work ( I'm at work right now )and will following your instruction to unplug fuse unplug red wire and so on, I don't know how to check diodes, please help ? Thanks

Thanks for help, Bill Kapaun help me check the switch, I think switch is OK.

ALSO check that there is no continuity between the switch terminals and the BODY of the switch in the HL or ON position. If there is that would be the short you're looking for.

ON the SWITCH TEST-
With ONE lead on the B terminal-
CHECK for continuity to ALL the other terminals.
Compare to the "Truth Table" at the bottom of the schematic.
IF a combination isn't listed as having continuity in a specific switch position, it means it shouldn't.

In EACH switch position, you'll check 6 other terminals.
B to G,M,L,S,A&Y (G should be grounded to the body. If it isn't, also check B to the body in each position)
That means there are 24 (or 28) different combinations.

First of all I thank you all of you had been posting here to help me fix my Tractor, special Thanks to Bill Kapaun spending time teach me to test all wiring, Finaly I got my tractor up and run, after following Bill instruction, switch is OK and I found a wire connect to Carb solenoid is touch with engine cover, when engine got hot it melt wire isolate and stich in metal, when I check that wire with one lead ground and other touch this wire I get continuity, I tape wire with black electrical tape and put all together just turn the key for start the engine start up , now I can cut my grass tomorrow, I'm glass to be come a member this forum, Thanks to all.

Truong Vu

I had the same problem...fuses blew as soon as I would turn the key. I done the wire check, battery, everything. I jumped across silinoid to start but the tractor wouldnt move or blades wouldnt turn on. When tractor was running when releasing clutch I would start to move but the mower would start to die until I pushed the clutch back in. I finally found a plug on the left side of the engine. (I think it is called an ammeter.) I unplugged this turned the key and to my suprise the fuse didnt blow. So I jumped on and it started. I put the mower deck on and again to my suprise the blades came on. Now the mower was running rough and maybe backfired a few times but the damn grass is cut. Will buy this part tomorrow lol. hope this helps someone.