Burnt Red Wire on Old Volage Regulator

[gweishaar]

I tried to start my Yanmar 1500D today which the 4th time since I bought it last weekend. It started fine before. When I turned the key nothing. I charged the battery and cleaned the terminals. I attached the pos to the battery and placed the neg black lead on the battery. I heard frying and removed the neg. In looking at the regulator under the steering wheel shroud (dashboard), the red wire was burned through. After disconnecting the battery cables, I checked the continuity across the battery cables and the circuit was closed (short circuit). After removing the fuel tank to get to the back of the "Dashboard" and removing the regulator and disconnecting the wires, I checked the continuity across the battery cables with the switch on and off and the circuit was open. With the voltage regulator removed and the switch on the continuity of all the connections to the regulator were open. No fuses seem to be blown. I rewired the Volt. Reg. in the again but when I reconnected the pos battery cable and touched the neg to the battery pole, there was a pretty good spark as if still a short. The old volt. Reg. is a 4 wire black is ground and the burnt wire was red (to switch) but the other two appear to be white (OLD and faded). The 2 whites go to 2 each push on connectors. I think I need a new voltage regulator??? and any help on where the 2 whites go???. Any help would be appreciated.

 

[reb]

I haven't had the regulator off mine to look at it, but I wonder if the case provides a ground connection when it is installed. That would account for it checking good when removed.

Did you by chance reverse the battery polarity when you hooked it up the first time? It seems strange that the short should develop when you had it removed.

It sounds like you need a new regulator. The white wires should go to the alternator.

 

[gweishaar]

Thanks Reb for your reply. The polarity was right since I burnt up a boat alternator some years ago and it is still foremost in my mind when I hook up a battery. I later discovered that I had pulled the light switch (to the right on the "dashboard") all the way out at some point in time and I now wonder if there is a short in the yellow light on the fender. I think this is also controlled by the headlight switch but since the light is burnt out and extremely rusty, it is not really evident. The wires leading to this look pretty worn and cracked. The tractor is at my lake house (2 hours away) so I will take a look at the wiring to the fender light when I go up this weekend. I will order a new regulator since I understand the life of a regulator is about 20 or 25 years anyway and the tractor is about a 1979 (I think). The regulator looks original. After I install the regulator and before I hook up the battery I will make sure the circuit is open.