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Curtis B.
Curtis B., Other
Category: Electric Vehicles
Satisfied Customers: 28046
Experience:  Worked on fleet of various electric vehicles, golf carts, scissor lifts and electric booms.
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Electric Vehicles Marathon: I own a 1985 ezgo marathon,

Customer Question

I own a 1985 ezgo marathon, the b atteries are new a year ago and fully charged. Two weeks ago the cart would not stop driving when you took your foot off of the accelerator. the speed was like the wiper arm was on the first contact button but the carbon button on the wiper arm is diffenatly resting on the idle button. I have the service manual for this model and for all the good it did for me I tested the system with a fluke 83III meter. The power seemed to be every where that it should be. With the rear end raised for testing we found that the motor speed was not consistant, sometimes the top speed was fully there and other times it wasn't full. This machine was given to me a few years ago so I don't know how much use was put onto it but other needing batteries it ran fine. I'm retired and handycaped and just use it for basic trans around by property. I decided that maybe the problem might be in the accelkerator panel and the wiper arm. I ordered and installed and new panel, wiper arm, tall solenoid and micro switch. No change, it still wants to drive in nuetral but now I get a high energy arc when the wiper hits the first driive button but seems to run fine on the other three buttons. None of the golf cart shops arouund me want to work on this old of a machine. Can you shed some light.
Submitted: 2 years ago.
Category: Electric Vehicles
Expert:  Curtis B. replied 2 years ago.
Check the resistor pack, there are three resistor coils in the box. If resistor is melted to one of the other coils ,can cause speed problem. As for the driving neutral, I would replace the solenoid as it has to make and break the circuit. Sounds like it is sticking. I had one of this same model and had it all over my shop in pieces!
Customer: replied 2 years ago.
Thank you for the response. My resistor is not in a box, however, I have not checked the coils to see if they are shorted. That will be my next step. However, keep in mind I installed a new solenoid on the accelerator panel and before installing the solenoid with my tester we checked it to make sure it was working correctly. When I ordered the solenoid there was two choices, a short one and a tall one. All I had to go by was visual and looking at the old solenoid it definitely was taller than a conventional solenoid so I ordered the tall one. This new solenoid matched up perfectly to the old one. I will let you know what the outcome is on the resistor coil. Thanks, again.
Expert:  Curtis B. replied 2 years ago.
!!I missed you changing the solenoid. The shorter/longer one would make no difference. But are you sure it is not staying closed from outside voltage source ? I assume you have a wiring diagram for the unit. Here is a link to one.-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Customer: replied 2 years ago.
My testing procedure on the solenoid was by activating the system with the key switch and with the forward/reverse lever in forward position, the micro switch closed the small wire which activated the solenoid which gives a closed circuit for the two heavy battery wires. I have to admit I'm a bit confused because there is a position which shows 36 volts on both sides of the solenoid. The wiring diagram and e-z go service manual does not really make it clear as to what happens when certain switches are turned on and off. My background for the past 45 years has been a repair mechanic on John Deere powered equipment. Just recently sold my business after 43 years. My training through John Deere has kind of spoiled me because for every system that John Deere uses regardless if it's electrical, hydraulic, etc. we never proceeded to repair a system unless we knew how the system operated, i.e. go to JD's Theory of Operation section. Theory of Operation would give us a flow chart and would explain to us exactly what happens if and when switches or turned off and on, which made it very easy for us to isolate complex problems. I really do not understand fully how this system works in these carts. For instance, all of the equipment I'm used to working on, the frame of the machine is connected through a ground system whereas the carts do not have a grounded frame. Sure would love to have a detailed theory of operation for this machine to understand how this electricity flows. Tomorrow I will be testing the resistor to see if possibly that is my problem, because I am baffled as to why this cart will travel low speed without the accelerator pedal being applied. Thanks again.
Expert:  Curtis B. replied 2 years ago.
I took all of the f/r micro switches out of mine and only left one on the foot pedal , to close the solenoid. Much to confusing for me on all the micro switch wiring. I was old diesel tech, and simple was always better.
Customer: replied 2 years ago.
Good morning CurtisI feel lucky that I hooked up with an "Old School Tech" with real life "Seat Time". Too often I'm confronted with young techs that are wizzes in new computer electronics but have no idea what to do with real carburetors or battery ignition with points and condenser. I like you have always peached "keep it simple". I also get real frustrated when I'm trying to repair something I don't understand, at that point for me it becomes a matter of principle. I'm pretty good with electrical repairs so long as I have a good tech manual with a good diagram. I'm not sure if I mentioned this or not but I have a handicap, I'm loosing the control of muscles in my arms and legs so turning wrenches won't happen. Along with help of long time friends I manage to keep up with problems like this one so as soon as these guys show up this morning I will dig deeper into this machine. I can't tell you how much I miss this machine, it's my means of getting around my property. I will keep you updated
thanks, Louie
Expert:  Curtis B. replied 2 years ago.
Thanks Louie for the response, I have some honey do's today, so I will be out of contact during the middle of the day.
Customer: replied 2 years ago.
Morning Curtis
Here is an update from them weekend. My son who is a service manager for a large John Deere dealership worked on testing the electrical system on this cart from 10:00 am to 5:00 pm yesterday. The control and power systems were tested at least twice following the steps in the ezgo service manual. We first visually checked out the resistor coils looking for any signs of over heating or damage, none where found. All switches and electrical paths were spot on, batteries up to full charge with static voltage at just over 38 volts dc. I mentioned before about the high energy arc between the park terminal and the #one terminal on the accelerator panel. This arc is jumping from the #1 terminal back to the wiper arm brush when the arm is parked on the park terminal and the wiper arm brush is not touching the #1 at all. This arc has actually burned a gouge in the insulated board between those two terminals and badly pitted both terminals and the end of the wiper arm brush. Keep in mind the accelerator panel, terminals and wiper arm brush were all new. I replaced the old accelerator panel and wiper arm just because, they really weren't worn out. So now we clean up the old accelerator panel, hand file the new wiper arm brush flat and smooth again and installed them. With the rear end of the cart up on jack stands we started testing the drive system. Everything ran perfectly, all four speed range changes were noticed which told us the resistor was working correctly. There was no arcing at all. We continued testing for about 15 minutes trying all possible accelerator variations. Now we decide to test it on the ground. We slowly pushed the wiper arm to the #1 terminal and immediately there was the high energy arc. Even when we let up on the accelerator pedal the arc continues to jump across to the wiper arm brush which is now sitting solely on the park terminal. By shifting the F/R lever to neutral it kills the arc.. Further testing results, We found that if you slowly advance the accelerator to the number 1 terminal and immediately let off, a high energy arc continues to jump from the number 1 terminal to the wiper arm brush on the park terminal. If we then take and snap the accelerator quickly it will kill this arc. We also find now if we advance the accelerator rapidly all the way to the number 4 terminal, everything seems to work perfectly, with very minor arcing as the wiper arm brush touches each terminal. If we do not linger on the number 1 terminal at all, you would never know there is a problem. The motor seems to run extremely strong. On the gravel driveway the wheels will spin gravel all over the place. At my wits end! Don't know what to do next. Please advise!
Expert:  Curtis B. replied 2 years ago.
Did you run a motor test and test it for grounds? I'm not sure you don't have a motor that has internal winding problem. Another thought I just had, was on the later model Ezgo's they put a resistor on the solenoid just to keep it from having voltage spikes. I don't see one on this diagram, but it could be added. Ezgo part # ***** Look at the solenoid test , talks about the resistor?
Customer: replied 2 years ago.
Hi Curtis,
I'm not sure if we are both on the same Service Manual. My manual is 19968-G1 Issued 8/1/85. I'm not finding anything about a resistor on the solenoid. Furthermore, I need help understanding where a resistor would be wired in and how does it work and what does it do?
I am having a terrible time understanding where this voltage is coming from for the high energy arc. Is this voltage actually jumping from the wiper arm brush forward to the number 1 terminal on accelerator plate? If so, there must be something that keeps the voltage flowing, but what?
Expert:  Curtis B. replied 2 years ago.
Here is site that has the solenoid test for the newer carts. It mentions the resistor. It has to be on the newer carts. Scroll down the opening page and find the tests. I'm not well versed on electrical problems, I just always figure it's something simple and not high tech. That's what I liked about my old Ezgo with the resistor pack! -------------------------------------------------------------------------------------------------------------------------------
Customer: replied 2 years ago.
Thanks for your help, but at this point I looked at the site you recommended but my cart does not have electronic speed sensors in it. Nothing that I'm reading there indicates it can help my problem. I need to move on and try to find someone who can help me solve this problem one way or the other.
Expert:  Curtis B. replied 2 years ago.
Motor test is the same, have you ran the motor ground test?