Is it the speed control?

[Spanky21]

Hello all, newbie here. I was cruising around in my cart the other night and when I let off the gas to turn a corner, the cart just stopped working. (It was fun pushing it with the wife and dog a half mile back home!) I did notice when I first pulled it out of the garage when I pushed the gas pedal it seemed really sluggish like it didn't want to go. Also I noticed the other night that when I would let off the gas and push it again, it acted like it didn't want to go. But after pushing the peddle a couple of times, it would pick back up and go. Lastly, while my pops and I were troubleshooting it, it would sometimes work in both forward and reverse. I took it down the driveway but it didn't make it back. The volts are good going to the solenoid and if I remember correctly, the volts going into the speed control box are good but go to zero coming out of it when you give it gas.

I'm pretty sure the cart is a 2004 EZ-GO Series TXT, 36 volt.

Any opinions? Any would be greatly appreciated.

[JohnnieB]

Jack rear tires off ground and put on jackstands so the half ton cart doesn't take off unexpectedly and run over someone of something.

Connect your voltmeter between the main negative terminal on the battery pack an the M- terminal on the controller.

Push pedal just far enough for the solenoid to click.
You should read Full battery pack voltage.
If you don't have it, troubleshoot the red and blue cables and their connection and the contacts and components associated with them.

If you do have full battery pack voltage, slowly push the pedal to the floor.
The voltage should smoothly decrease to Zero, or close to Zero.

If it doesn't, check the ITS (throttle) input to the controller.

If it does, and the motor isn't turning, you should see smoke or something ought to be getting mighty hot.

Let us know what you find.

[Spanky21]

Of all people to answer my thread, I'm happy it was you! Thanks for the info! My pops is a retired engineer and is convinced it's the speed control because the voltage dropped to zero. I read somewhere else it was supposed to. I'll get on those diagnostics as soon as I can! Thanks again!

[Spanky21]

Also, what is the "its"? Is it the little black sensor in the floor board? We did check it, but what should the readings be like? (If that's what your talking about)

[Great white north]

That module in floor board is indeed the IT'S there should be a micro -switch with the module check continuity of the switch and or wires
Check stickeys on electric Ezgo on site
Note when you press on gas and hear solenoid click ? Do you have pack voltage ?
Then when you press gas all the way down it should go to zero like Johnny said

[yurtle]

Links:

Owner's, Parts, and Service Manuals:
http://www.buggiesgonewild.com/elect...g-manuals.html

[JohnnieB]

Originally Posted by Spanky21

Of all people to answer my thread, I'm happy it was you! Thanks for the info! My pops is a retired engineer and is convinced it's the speed control because the voltage dropped to zero. I read somewhere else it was supposed to. I'll get on those diagnostics as soon as I can! Thanks again!

Tell your pops that the control element (about a dozen MOSFETs connected in parallel) of the controller is located between the B- and M- terminals on the controller.
The control element is switched on and off at about 15kHz producing PWM (Pulse Width Modulated) DC and the duty cycle determines the Amperage the motor is allowed to draw.
When the pedal is up, the Duty Cycle is 0% and the voltage drop across the control element is 100% of applied voltage.
When the pedal is down, the Duty Cycle is 100% and the voltage drop across the control element is 0% of the applied voltage, plus about 300 Milli-volts per 100A of current flow through the control element.

However, your pops isn't wrong, just looking for the right thing in the wrong place.
If the voltage was measured between the controller's M- and B+ terminals, then you are measuring across the motor and the voltage would be Zero with pedal up and full battery pack voltage with pedal down.

Here is a block diagram of a series controller, that shows the differences in what the two voltage measurements mentioned above are looking at.
(You have a Curtis 1206 controller rather than a 1204/1205, but it works the same.)

And another attachment that shows what the wave-shape actually looks like.

[JohnnieB]

Originally Posted by Spanky21

Also, what is the "its"? Is it the little black sensor in the floor board? We did check it, but what should the readings be like? (If that's what your talking about)

ITS = Inductive Throttle System

Three parts to the system, constant voltage source in the controller, sensor coil in the pedal box under the floor mat and a throttle position translator in the controller.

Basically, when you press down on the pedal, an iron slug is inserted in the the sensor coil in the pedal box, changing the inductance of the coil, which in turn tells the controller to pass more current to the motor

The voltage at Pin-2 (Black wire) should be 9.0V to 11.5V
At Pin-1 (White wire), with pedal just pushed until the solenoid clicks should read 0.4V - 0.6V.
With pedal on floor, it should read 1.5V - 1.7V

Download the manuals yurtle linked to.

[Spanky21]

Turned out to be a simple problem. Replaced solenoid and now the cart goes. Encountered another problem however... When you punch the accelerator, it jumps like it's supposed to, but then suddenly slows down, almost feeling like it "drags", but eventually gets up to full speed. I'll start another thread reference this problem.