1992 EZ GO Marathon

[mike71]

Good Morning Everyone. I'm new to the forum but have been lurking for a few days. Thanks in advance for the replies that I might receive concerning the troubles that I am having regarding a '92 Marathon 36vdc that doesn't go when pedal is depressed. I have performed several tests after reading through some of the posts on this site.

System voltage is: 38.06
Individual battery voltage is as follows: 6.25, 6.325, 6.3, 6.31, 6.33, 6.36
Key on pedal pressed: 36.5

With neg probe on (b-) I get 35.5v on the controller side of the solenoid(pedal pressed).

The back-up buzzer works.
I've jumpered across the 2 large posts on the solenoid, pressed the pedal with no result.
The solenoid clicks when pedal is pressed.

I'm not sure where to go from here and could use some guidance. Thanks

[72volt_ezgo]

Hello Mike!
Thanks for doing your homework and checking the basic things first!

I would next see if your controller is working or not by checking voltage between B+ and M- at the controller as you press the pedal.You should see the voltage changing to near battery pack voltage at full pedal.

If that's not happening then disconnect the 2 wires going to the potentiometer (at the controller) and check ohms from pedal off to slowly depressing it to full pedal and you are looking to see somewhere near 0 to 5k ohms! (checking pot)

Before all this take a look at all cables on the cart and make sure nothing is has fallen off/melted off any terminals including the terminals on the motor!
Barna

[mike71]

Thanks for the quick response!! I will check the voltage between B+ and M- when I get home this evening. I will also raise the cart on jack stands and check the voltage at the motor.

[mike71]

This evening when I got home I checked the controller by testing between B+ and what I believe to be M- (I tested between the 2 with the diode). The voltage matched the battery pack voltage with the pedal half pressed but actually lost 2volts at full press. The controller is a Curtis PMC 275amp 24-36volt(if that helps).

I'm not sure which wires to check on the motor but did check between A1 and S2 and got 1.8v-5.5v(increasing as I pressed the pedal farther)--wires seemed to be in good shape and tightly connected.

I appreciate the help that I have been given so far but could use some more.

Still a little confused about how to check the potentiometer(if that's the next step).

Thanks

[fishb8]

Mike, as 72volts said, check the potentiometer. I believe there are 3 wires from the pots to the controller. take the black and white wire(i think those are the right colors) off the controller and put your ohm meter on them. press the accelerator and it should move slowely between 0 ohms and 5000 omhs.

I hope I'm not leading you astray, I'm going off memory.

[72volt_ezgo]

Mike,by your description of voltage increase it sounds like your potentiometer is working good but to make sure it does, you would disconnect pin 2 and 3 ( 1 is close to the edge of the curtis),put your meter leads in those two wires and look for close to zero ohms at no pedal and close to 5000 ohms at full bore. (even controller sounds like it's good so far but not sure yet. The fact that you matched pack voltage indicates to me that there is absolutely no load on the system= open circuit passed the controller)

I am now suspecting that the current can't make it to through the loop due to an open either at F&R switch or in motor.
To check the motor put cart on jack stands.
I would put the F&R to neutral to avoid shorting things out in the next steps!

If you have battery pack + at A1 then jump A2 to S1 and put battery pack negative to S2 OR ( + at A1) and jump A2 to S2 and give it battery negative to S1! (rotates in the other direction)

It would be safer with the actual main battery pack connections disconnected even the motor connections and then you would use your own separate 12V power source (2 - 6V batteries in series or a 12V car battery )

Depending on how brave you are Jumping the whole battery pack power and voltage might be a good spark and some rather violent motor acceleration so with the rear jacked up either way I would probably go with 12V option!

If you decide to disconnect cables LABEL THEM! Believe it or not you will not know where they were despite how easy it looks before removal!

Disconnecting motor connections will require two wrenches or you risk spinning the stud in the motor and braking the wires inside if you don't hold the stud under the nut and cable with another wrench!

(Oh and I wouldn't worry about the 2 volt drop from half to full pedal,I think all it means is your cart would do full speed at what seems to be half pedal and then no more power beyond that)

Give that a try!
Barna

[mike71]

You Guys have been very helpful. Is there a good method to checking the F-N-R lever or a way to bypass it in order to see if that might be the problem? The only thing that I know about it thus far is that the back-up buzzer works. Should I remove the handle(not sure if there is a set screw or handle just pries off) and inspect the switch itself. I don't see any disconnected wires but may need to remove it in order to have a closer look.

I will check the potentiometer this evening by the method that is described above. I have the cart on stands but will have to check the motor tomorrow.

[72volt_ezgo]

Find screw in handle (on mine it used to be at end of shaft/middle of handle straight back but my screw is missing),remove and pull/wiggle handle. Depending on how much rust holds it on shaft you may need to use two flat screwdrivers on opposite sides to wiggle/pry off.

The problem with electrically checking the f&r is that you would need to know which sets of two wires are being connected in what position of the switch so you will have to look in at the sides of the switch and you will see the contact pads(4) and the connecting buss bars(2), inspect them,make sure they are touching with pressure,and that you see copper and not burned surface. Once you see what wires connect,you could do your own continouity test.Which I would do with at least a light bulb load and not just an ohm meter.
Take a look at it first though!

Barna

[mike71]

Retest and Update.

Batt. Pack voltage= 37.9

Batt. Pack voltage with pedal pressed= 35.9

Ind. Batteries = 6.25, 6.33, 6.26, 6.32, 6.24, 6.3

Jumped Solenoid and no cart movement.

Tested Controller between B+ and M- with pedal pressed = 7vdc (?)

Checked Potentiometer between blk and white and Ohms increased up to 6,500 at 3/4 pedal press then it drops as you continue to press pedal farther.(?)

Solenoid clicks when pedal is pressed.

Buzzer works when lever is in reverse.

Tested Controller with red probe on the Solenoid post that leads to the Controller and black probe on Battery Pack negative and = 35.9(pedal pressed) and = 32.4(no press).

I removed the F-N-R switch and there were no loose or burned wires(visual inspection).

I don't understand the 6,500ohms or the 7vdc. Any ideas.

Thanks again!

[72volt_ezgo]

Sounds like your controller is bad!

Don't worry about the 6.5K ohms. The controller probably doesn't care for anything below 300 ohms and anything above 4500 ohms. (just guessing).
Went outside and checked my pot,it sits at 1 ohm and goes to 6.89K.

I would still check the motor!
Barna