Burned connection to key

[Minos027]

Hey guys, noob to the carting world here. Here's my issue, I have what I believe to be an 83 textron. The problem first started with the "key not necessary" problem which went hand in hand with the "put it in gear and it takes off" problem. I searched around on this forum and found that my issue was most likely the solenoid. So, I replaced it being careful to put the new one in the same way the old one came out.

Upon completing this task, I put the key in, turned it to on and was met with a small flash by the solenoid and smoke from the key switch wires. Turn the key off, disconnect battery.

I found the wire on the back of the key switch had melted its connection and the resistor looking item on the side of the solenoid had, in essence exploded...

I have no idea where to even begin. Please help.

[JohnnieB]

Welcome to BGW!

Sounds like the diode on the solenoid's coil terminals was installed backwards.

The diode's cathode end (end with the white band around it) connects to the terminal with the most positive voltage on it.

The resistor that connects between the main solenoid terminals, isn't polarized and can be installed in either direction.

[Minos027]

Thank you for the response. However, no diode installed on this one, just the resistor across the two small posts.

Does it need the diode? It did run without it before I change the solenoid. Could there be something different on the inside of the solenoid that would make the diode necessary? The solenoid looks exactly the same as the old one, obvious exception being "shinyness" lol.

[Gonkulor]

Has any other work been done on the cart before this problem?

[JohnnieB]

Originally Posted by Minos027

Thank you for the response. However, no diode installed on this one, just the resistor across the two small posts.

Does it need the diode? It did run without it before I change the solenoid. Could there be something different on the inside of the solenoid that would make the diode necessary? The solenoid looks exactly the same as the old one, obvious exception being "shinyness" lol.

The resistor goes between the two big posts.

It doesn't "need" a diode or resistor to run. They simply extend the life of some switch contacts by reducing the arcing when they open/close.

If your cart is a 1983, it is likely to be a Marathon with a resistor type drive system.
If so, they didn't have either according to the schematics I've seen.

Since the cart doesn't have a controller with filter capacitors in it, the resistor has no purpose, but a diode across the solenoid coil would protect the contacts in the pedal switch. so it would be a useful addition.

Here is a schematic of a resistor drive system with the solenoid activation circuit highlighted.
It may or may not match up with your cart's wiring because Marathons were wired in more than one way and who knows what previous owners have done.

[Minos027]

Yeah, I have no idea what's been done to this thing. I use it for work (I work for goodwill doing commercial service work) it had apparently been sitting at the shop for some time. Somebody stole the batteries out of it and screwed up a bunch of the wiring in the process. So we took it to a local shop and had new batteries put in and wiring repaired/replaced.

Would pictures help you guys diagnose what I have vs. What I need? I could be describing something completely wrong. If so, I will post pics tomorrow as I do not work today.

Johnnie, if the resistor is not needed, 1) why would someone put it there? (Not trying to start a fight, I just don't understand)

2) should the cart work if I took the resistor out and repaired the key switch?

[Gonkulor]

Back to basics would be a great starting point. There may have been something wired inappropriately long ago. We need to rule that out first.

Sorry JohnnieB but I smelled something a foul at the beginning.

[Minos027]

Spiffy...

[JohnnieB]

Originally Posted by Minos027

Yeah, I have no idea what's been done to this thing. I use it for work (I work for goodwill doing commercial service work) it had apparently been sitting at the shop for some time. Somebody stole the batteries out of it and screwed up a bunch of the wiring in the process. So we took it to a local shop and had new batteries put in and wiring repaired/replaced.

Would pictures help you guys diagnose what I have vs. What I need? I could be describing something completely wrong. If so, I will post pics tomorrow as I do not work today.

Johnnie, if the resistor is not needed, 1) why would someone put it there? (Not trying to start a fight, I just don't understand)

2) should the cart work if I took the resistor out and repaired the key switch?

Pictures would help identify what you have and what has been done to it.

If it is a resistor drive cart, the 250 Ohm 10 Watt resistor across the solenoid contacts has no purpose, but if it has an electronic speed controller it has purpose. With the exception of resistor drive electric carts, a "Pre-Charge" resistor is needed to pre-charge the filter capacitors in the speed controller so there isn't an extremely high inrush of current through the solenoid's contacts when they first close.

Until the cart's drive system is positively identified, I cannot say if a resistor should be installed or not.

As to why it was installed if it wasn't needed. Not everybody that works on carts fully understands its purpose and it is needed on most carts.

On the other hand, a diode should be installed across the solenoids coil, because when the solenoid is de-energized, a huge voltage spike is generated by the magnetic field collapsing and the diode shorts in back into the coil harmlessly rather than it impinging on the switch contacts that are in the mechanical progress of opening and arcing across them, shortening their useful lifespan.

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Unless something else is wrong, the cart should run if the keyswitch and wire to solenoid coil was repaired.

The resistor and diode simply prolong the lifespan of some switch contacts and the cart will run without them.

[Minos027]

Ok, I will get pictures up tomorrow early morning. And again thank you guys so much for your help.