Dead cart, where to start?

[FarmerMatt]

HI gang,

I've got a 1996 Cushman Titan IV (48 Volt) that is dead in the shop. I took it to the local service center and they said I would have too much work in it to be worthwhile if they took it on. Maybe they wanted to sell me a new EZGo?

Anyway here's some details:

Last fall I had some problems where the cart would drive itself, if left in forward gear it would creep along until it hit something. The parking brake never worked all that well, but we were used to it being "off" when nobody was using the throttle pedal. The solenoid seems to have failed (in the on position) sometime over the previous year because we could drive it with or without the key.

So I played with the POT a little and it just made it worse. I put it up on a jack stand and tried adjusting the POT but it was either full on or full off. So silly me I tried driving it in the full on position... I jammed it into gear, smoked the tires and away we went on a little joyride, much faster than normal around the farm. I knew something was amiss when the forward reverse lever started to smoke ohmy.gif

So I pulled it out of gear and parked it for winter. This spring we got some money together and hauled it to the pro shop but they discouraged me. They said because somebody down the road had done some home-brew wiring, they would need to rewire the whole cart to match the wiring diagram. Plus they weren't sure if the speed control or motor were damaged in the highspeed run.

The battery bank appears to be smoked which totally blows, there's at least $800 to start. Not sure how the bank got fried but maybe in the overheat the insulation on the positive cable melted and it contacted the negative terminus of the bank. I can't see how we didnt end up with a bigger mess actually. The bank is holding at about 48 Volts but its capacity seems to have gone way down, I put the AC charger on it for an hour and they started to bubble over right away, whereas normally I can charge them for a few hours before the charger shuts off automatically around 60 V.

The little circuit board also has a blown wire which I tried to resolder but I'm not sure if that was the only damage to the board. I've got the battery bank hooked up but not getting any response from the solenoid, but I'm also not sure what the guys at the pro shop did before they called it quits.

Ugh so I am pretty discouraged but dont want to give up on this cart, when its working right it kicks butt and is super handy around the farm. I am interested in taking a stab at getting it back together, but every time I try to work on this bad boy I just end up farting around in the dark. I have the parts manual which includes a wiring diagram, but I don't have any kind of troubleshooting or repair manual.

Anybody got any guidance, where to start, basic principles of EV cart troubleshooting, etc? I'm tempted to bypass all of the harness (and control board), see if I can jumper the solenoid and just make sure it still "runs" on a jack before I get too far into it. But in the long run I need this cart to be safe, with shutoff features like a key, operator presence switch in seat, etc.

Thanks for any guidance you can provide!
Matt