89 Marathon S/G melting DF wire
 

I have a 89 Marathon with a 3pg motor. Rebuilt it last year and about a month ago got it out for the season and it has run great, me and the fam have really enjoyed it. Just recently it left me stranded a couple miles from the house with my wife and 2 yr old. (we live in a lake community and golf carts are used to cruise around the lake and to amenities). We had to be towed home.

When I took a look the DF (small green) wire from the S/G was completely melted from the S/G all the way back to the voltage regulator. I replaced the wire.

I then got on and searched the forum to see what could cause this.
I was able to find how to check the charging circuit.
I removed the drive belt and disconnected the DF from the voltage regulator and connected it to ground. With my multi-meter set to DC volts, I clipped my probes to the battery and got 12.3 V. I then started the cart. My meter immediately reset its self and would not give me a reading until I let off the gas and the motor stopped it would then read 13 V.

From my research this test should have produced 17-18V. I then re-ran this test with the DF wire connected to the voltage regulator and got the same results. I should have expected to see 13.5-14V.

I then replaced the voltage regulator with a new one and got the same results.

This is very odd to me. My meter is rated for 600V and you wouldn't think that the S/G would be outside that range.

So now I wanted to validate my meter was working correctly. I took it to my Jeep and clipped to the battery got 12V then started my Jeep and got 14.5V. This tells me my meter is working properly.


This has me a little confused though. Either my ignition coil is feeding into my charging circuit or i am severely overcharging from the S/G.

I have checked the wiring multiple times to the wiring diagram and i cannot find any problems. Everything seems to be connected properly.

My guess is the S/G needs to be replaced but I just want a sanity check here before i spend the $$$ on one.

Any shared experiences or suggestions or other tests to run would be greatly appreciated.

Re: 89 Marathon S/G melting DF wire
 

i'm guess this isn't a commonly seen problem.

Re: 89 Marathon S/G melting DF wire
 

bump

Re: 89 Marathon S/G melting DF wire
 

Still haven't solved this anybody have any ideas?

Re: 89 Marathon S/G melting DF wire
 

It sounds like it might be struggling to find a good ground.

The negative battery cable should be connected to the frame. From there, you should have a large cable going to lug C which is located at the bottom of the FnR switch. From that same point on the frame, there should also be a large braided cable that attaches to the engine. Do you have that?

Re: 89 Marathon S/G melting DF wire
 

From memory I know it goes from battery to frame to braided cable that attaches to the engine( had a problem where that was loose and would cause the engine to cut out intermittently) . I will confirm it goes to the C lug. I will also give them all a good cleaning and make they are not corroded.

Re: 89 Marathon S/G melting DF wire
 

The grounds are present and properly hooked up.

Re: 89 Marathon S/G melting DF wire
 

Put it in forward. Hook your meter directly to F2 (positive), and A2 (negative). Let's see what happens there.

Re: 89 Marathon S/G melting DF wire
 

I wonder if the df stud has rotated, and is shorting out on the inside of the inside of the starter.

Re: 89 Marathon S/G melting DF wire
 

I still get the same thing at F2 and A2.

So disconnect the DF and see what it does?