EZGO '99 shudders, replaced batteries, solenoid and resistor

[JessiJD]

Hi all. Don't know if I posted here before, but I have come to this forum a lot to troubleshoot my problems. I appreciate all the info I have found so far!

I am getting fed up with this cart (EZGO E299, DCS, Nothing fancy). I am about to take it to a repair shop, but am trying here for one last attempt at finding the problem because the repair shop charges $100 an hour and I have already shelled out $800

I have had this cart for 4 years, batteries were getting old and a few terminals were getting really corroded, so when the cart stopped working, we just replaced the batteries and all the cables. Charge is really good and holding at 6.88v.

When the new batteries didn't work, I went through there the trouble shooting diagrams here. We lifted the rear wheels and the wheels would spin and the motor was running. It would even change speed while the rear wheels were lifted. There was some "sticking", so we pulled the wheels off and greased the axles, checked the brakes (all good) They now spin without any problem.

I tested the controller and solenoid. The controller tested out as fine. The solenoid seemed "off". It would switch between holding the battery voltage and dropping 0.01v. And at the time I noticed one of the resistors had blown. So I replaced the solenoid and the resistor.

I am now incredibly frustrated. Any other ideas? I press the pedal, I hear a click, it moves 1 inch and then just shudders. It must be coming from the same original problem because it has been doing this since it first stopped working. New batteries, cables, solenoid and resistor don't seem to change it. Should I go through all the trouble shooting again? I am so confused!

Ideas? Should I just take it in? I am getting desperate because it is our farm cart and we have a 3 year old son. It is getting very hard and unsafe to tend to the livestock without having a place to "park" our son!

Thanks,
J

[JohnnieB]

The cart will run without the resistor and diode installed, and they sometimes cause confusion while troubleshooting, so remove them until we get the cart running.

Measure your battery pack's voltage and then connect your DVM's test leads between the B- and M- terminals on the controller.
Press pedal only far enough for solenoid to click.
You should read FULL battery pack voltage.
If not, there is a problem in the high current loop, which is highlighted on attached schematic.

Let us know what you find and we'll proceed from there.

Note: be sure to put Run/Tow switch into Tow before connecting/disconnecting any electrical stuff.
Also, lift rear wheels off ground and put on jack stands so the half ton cart doesn't take off unexpectedly and run over someone or something.

[JessiJD]

Thanks for the reply! This morning I did what you said. Fully charged batteries read out at a total of 38.4v. When I first placed the DVM's leads to the B- and M- and didn't press the pedal, the DVM read 38.4v. When I pressed the pedal to the solenoid click, the voltage dropped between 3-6 volts (going back and forth). Resistor has been removed.

NEW Development: now with the rear wheels jacked up, they won't spin anymore.
Thanks!
J

[pete959]

this isnt the proper way to do it but bypass the noid and see what happins shouldnt be dropping 3 to 6 volts

[JessiJD]

Thanks for the reply, but I am going to need a little more clarification. What would be the proper way to do this and how exactly do I bypass the solenoid? And if I bypass the solenoid, what am I looking for?
Thanks,
J

[JessiJD]

Just tested the B+ to M- and the voltage is only going to 7v when I press the pedal.

[JohnnieB]

With the Resistor and diode removed, there shouldn't be any voltage between B- and M-.

Maybe there's some crud on top of the controller or between the big terminals on the solenoid.

There are two issues here.
1. Phantom current path bypassing solenoid contacts. (Getting voltage between B- and M- before solenoid contact are closed)
2. Solenoid contacts not closing. (Voltage between B- and M- should got to pack voltage when pedal is pushed only far enough to close solenoid contacts)
The fact that the voltage via the phantom current path drop to 3V-6V, simply means it is a high resistance path and the controller draws more current when it activates the solenoid.
-------
As for bypassing the solenoid contacts. You can move the cable from the B+ terminal on the battery pack to the other side, putting both input and output cables on the same terminal.

Or if you have a set of car battery jumper cables handy. Connect one of the pair to one of the big terminals and the other end of same jumper cable to the other big terminal.

No matter how you do it, be sure to have the Run/Tow switch in Tow while connecting/disconnecting anything.

[JohnnieB]

Originally Posted by JessiJD

Just tested the B+ to M- and the voltage is only going to 7v when I press the pedal.

The voltage between B+ and M- should start at -0- when the solenoid first clicks and increase to something close to full pack voltage as pedal is pushed to floor.
Conversely, the voltage between B- and M- should start at full pack voltage when the solenoid first clicks and decrease to something close to zero as pedal is pushed to floor.

You are most likely using a DVM with a meg-ohm or greater input impedance and they will read voltage when there is only a hint of conductivity.
What you are seeing probably wouldn't make the needle twitch on a old 20K-Ohm/volt analog Voltmeter.

[JessiJD]

Again, Thanks for all the advice. I pulled all the wires out to clean and test continuity, but before I even got that far, the S1 and S2 wires to the motor were rubbed to the copper and the copper was touching the metal frame. I am hoping that this could be the problem? Thinking about going ahead and replacing the A1 and A2 cables because of small cracks.

I'll report back once I have replaced them, but could someone explain what the S1 and S2 wires do?
Thanks!
J

[pete959]

s1 and s2 r ur forward and reverse i think