Cub Cadet 1641 Electrical Issue
 

I am rebuilding a CC 1641. It's all back together. I was having issues with the electrical blade clutch engaging. I figured it to be a ground issue. In the process while jumping a wire from the rear of the ignition switch, I noticed that every time I started the tractor I was frying the jumper wire. Everything is normal after the starter is disengaged. Why am I frying the wire just when the starter is engaged? I have a good ground to the starter. Bad relay? Starter? Any help would be appreciated. Thanks.

Well....... why are you jumping a wire? What wire are you jumping? I would say you are frying it, because it's not supposed to be there. Don't do that anymore.

I'm jumping the ground wire (Green) from the back of the ignition switch to ground.

What is that...???? :Huh:

I guess you would call it the PTO

unless I ground that one tab (that the schematic shows as ground) the lights and the PTO do not work. very frustrating.

Ok, the lights and PTO do not ground through the switch. The switch case is grounded, and so are the lights and PTO. But not through the switch.

This terminal is the grounded one. The lights, PTO and motor will all work and run whether this terminal is connected or not. Only thing is, you won't be able to shut the tractor down with the key. (Still may work though as the switch body itself is also grounded. This wire is a "just in case".) Find and repair your bad ground, and check the key switch for a short to ground through the start terminal.

Attachment 51772

Ok. Very good info. It is a new key switch and I did check everything. I do have one question. Should that one tab which you have marked go directly to ground? When I got this tractor, there were two green wires that were attached to your circled tab in your photo. I'm starting to think that those two wires go directly to ground.

I went out and pulled the two green wires off of your circled tab. I then grounded the two wires to the frame. There is no wire from your circled tab. I started the tractor, the lights work, the pto runs and when I turned the key off the tractor stopped.

One of the green wires makes a run over to the R.H. side of the motor, where IIRC it isn't used. The other, again IIRC, goes over to the L.H. side of the battery tray where it grounds to a condensor of some sort, then runs up to the lights. Not sure about the condensor part, I don't have one here to look at that is complete. But yes, the green wires run to a ground. I am pretty sure it's over on the L.H. side of the battery though.

fyi, the ignition switch is not grounded to the frame. It is being held in place on the tractor in a plastic mount. There is no metal to metal contact.

Well, the switch base itself is grounded to the tang. If it were touching metal it wouldn't need the wire. Honestly, now that you say that, I remember that it is bolted to the plastic part.

There has to be a Green Wire to the Ignition Switch ground terminal from chassis ground (or battery negative terminal) for the switch to work correctly. The PTO and the lights have their own ground connections.

I'm going to suggest not to put it directly to the battery. Here's why. That wire is a direct short for the mag to discharge the spark. I know that the frame is basically a direct ground, but if something went wrong, it could put quite a bit of voltage directly to the battery. It's kind of like, not using the negative post of a battery to ground a spark plug for testing. It's just not safe.

:Huh::HeadScratch:

IF - the electrical system is properly fused, one would not have to worry about "high amperage".

1641 wiring diagram. If you need a larger version of this PM me your e-mail address and I'll send it to you.

Thanks guys. Sorry, I've been away for work. I'm really miffed by the whole thing. As it stands now, every thing works, pto, lights, starter etc. but the ignition switch is not grounded in any way. Im not frying anything either? I'm wondering if something is shorted to ground somewhere. Remember in the beginning, I said I only fried the ground wire when the starter was engaged. Any ideas?

The discharge from the magneto isn't fused. Neither is the ground. A magneto puts out a high amount of voltage (on these magneto's probably somewhere in the 30,000 volt range) but a relatively low amperage. I think it's safer to keep that as far from the battery as possible. Probably would never have any issues..... just my opinion.


Yes, a short. You'll have to search for it. Shorts can occur anywhere. We would have no way of knowing where to look. If it were here at my shop, I'd start looking in the starting circuit, specifically the key switch, as it only cooked the wire while starting.