3 wheel ez go takes off as soon as F&R is selected

[interstate]

Trying to help a neighbor with a vintage EZ go 3 wheel cart. As soon as forward or reverse are selected the cart wants to take off without touching the accelerator. The brakes have to be dressed very aggressively to keep the cart under control, and of course a coil in the back does get red hot. Switching back into neutral stops the power instantly.

I inspected the speed selector and also the F&R switch, both look to be in surprisingly great shape. The pedal advances through the contact pads properly.

What should I check and how do I test/troubleshoot?

Thanks for your help, folks.

[camaroluvz28]

It sounds to me like your solenoid may be welded open...fairly common, I would check the microswitch that activates the solenoid and the solenoid itself...

[scottyb]

In addition to the solenoid being welded your speed wiper arm is not returning to zero.

[interstate]

The speed wiper has five contacts on it. The bottom one has no wire attached to it. There are then four contacts above it that each have a wire attached. At the resting position of the accelerator the wiper is perfectly aligned with the bottom contact that has no wire. The wiper smoothly transitions to each other contact and stops properly aligned with the last contact at the full throttle position. Thanks for the suggestion to look here. Unless I am missing something more subtle things look good here.

I see one solenoid on this cart. Can someone tell me how to check it? Can a continuity be used some how? I don't understand the function of the small terminals and the larger terminals.

I did notice one other problem. The bottom coil in the rear has a very frayed wired. This is the very bottom wire where it is crimped to the terminal that then is bolted onto the bottom leg of the bottom coil. What problems could this cause?

[interstate]

More research and testing...

disconnected the solenoid wires. Tested for continuity going through the solenoid between the two large posts. No buzz, no continuity.

I then found 36v and used two small jumper wires to bring that voltage to the small terminals of the solenoid. When I apply 36v to the small terminals the solenoid will click and continuity flows between the two larger terminals. When I remove the 36v the solenoid will click again and open the circuit between the two large terminals.

Did I test this properly?

Where do I look next?

The cart does stop in neutral. In forward it wants to take off right away. In reverse it wants to take off right away.

Wiper appears ok, solenoid appears ok, and micro switches are activating solenoid properly because it does shift gears properly.

[madoc1]

the solenoid is a switch. the small terminals are either pos or neg. makes no diff which side you hook the pos to, the neg goes on the other side. when power is turned on, a magnetic field is created which draws a contact up to connect the two large posts. with no power there should be no continuity between the large posts. sometimes the contact will fuse the two large together, giving continuity all the time (bad).

oops. you tested correctly!

[interstate]

I don't know what to check next.

[camaroluvz28]

I would check all wiring against a diagram...

[interstate]

So far all looks good.

Plus, cart wired great and then one day they put the cart in gear and it lunged forward. Same in reverse.


If that frayed wire on the bottom coil terminal was touching the frame, what would be the result?

[camaroluvz28]

If your reff to the hot wire from the battery to solenoid then cart could do this...I would repair wire and see if it helps...frayed wire is never a good thing and can cause heating/melting/running probs...