'96 Carryall Club Car took off by itself. Why?

tallyho

I drove my Carryall to the barn, got out, left it in gear and with the key on, and got in my tractor and started cutting grass. After about 45 minutes I saw my Carryall take off running wildly and then crash into a fence.

I was about 1/4 mile away and when I got to it I could smell wires burning and quickly turned off the key and put it in neutral then got tools and undid the battery cables.

Upon examination, most of the wires on the motor controller were about burned off and the controller was swollen up and leaking, definitely burned up. All the wires were in good shape yesterday when I checked it and put a little water in the batteries. With a new controller costing almost $500 I am hoping that this and some wire replacement is all that is needed to repair it.

What could have caused this to happen?

BGW

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jjance

Safety solenoid welded shut or somehow bypassed.

joesam

Here's my guess. Many carts manufactured in '95 & '96 had a (quickly discontinued) throttle mechanism called "continuously variable potentiometer". Because your key was on and "in gear" - it failed and essentially drove the cart (same as if you sat in it and pressed the go pedal)- just like you described. That device and failure was a known problem. In the years since, the throttle device in Club Cars was constantly upgraded with an endless series of mediocre potentiometers, eventually ending in MCOR 4 (which has a good record of performance). You can actually buy a kit to upgrade your cart to MCOR 4.

tallyho

I put a MCOR 4 on my cart last year.

I haven't checked my solenoid yet to see if it was bad but it was not hot when I touched it. The motor controller and all the wires leading to it were too hot to touch. The motor was cool, I hope that is good news.

joesam

There goes that theory!

Sergio

I had no idea You could fit an MCOR on a 1996 pedal assembly

Joesam, that was a good guess, I recall helping someone with a 96 (0-5kΩ) throttle and much to my surprise the controller would default to full speed if the throttle wire was disconnected.

That design would qualify it as a great engineering failure.

scottyb

It's likely the controller burnt up after the cart came to rest into whatever stopped it, the control was still passing all the juice the then stalled motor was calling for. Creating immense heat.

Can you test the throttle input signal now to see it is normal?

tallyho

This sounds logical but I am a novice and do not know how to check the throttle input signal.

tallyho

joesam, you may be right. I just remembered that the new MCO4 I installed was in my other Club Car, a 2009 model.

I just installed a new motor controller in this cart and it will not go when I hit the gas. The solenoid clicks when I turn on the key or change from forward to reverse but no go.

Now I have to figure out how to diagnose my problem.

tallyho

To check the throttle input signal, do I connect an ohmmeter to the wires I remove from terminals 2 and 3 on the motor controller? Which I presume would go from 5K to 0 as you press the accelerator if it is working properly? If this is the right way to check it, my meter reads 5K and never changes as you push the accelerator.