Resurrecting the dead 1991 Marathon

[ksmillie@yahoo.com]

So, its been about 5 years since the 1991 Mararthon last ran...no problems to recall.....went and got 6 new batteries, charged overnight...first problem solenoid is bad...no rattle at all.., get new solenoid,,clicking like a hammer!

Engage pedal, cart lurchs to full power at touch of pedal (not right)...runs about 20 feet and stops.....let it sit for 15 minutes....runs like banshee, again top speed at slightest touch of pedal..stops after 20 feet....do this over and over again....plug charger in (old trusty always worked) will not click and turn on...hmmm?
try a second different charger, it clicks hums....seems to be charging but no indication on meter....Cart is still taking off at full speed at slightest touch of pedal...but stops in 20 feet.......all battery connections spotless, brushed and tight, cables all good....(connections to motor and controller not checked, but look good)....all small wires look good and no changes or mods to wiring since last known good configuration....

I have repaired this cart many times over the years and always comes around with a solenoid but this time Im concerned it may be controller....any ideas?

[bronsonj]

Could be the throttle.

Is your cart a resistor cart or a controller cart? If it's a resistor cart it wouldn't be the throttle.

[ksmillie@yahoo.com]

controller....I checked the model number today, it is actually a 1992 ezgo marathon.....when it sits for a while, it will go, but it launches into highest speed immediately and drives for a few seconds then it quits....like it has a thermal cutout or something....there is no "sneaking up" on the pedal...it lurches and goes full speed at the slightest touch of the pedal. But definitely a controller with B- and B+ on two of the four posts.....the controller has never been disconnected as far as I know and I have had it for twenty years...It has a full charge but I am charging it again until it stops and will do it again but I am certain that the batteries are charged,,,they show almost 43 volts when charging and 38 plus when not charging...another indicator is when I touch the pedal, the headlights or stereo do not even dim or blink, batteries are charged!

I will start diagnostics tomorrow but the simple truth is, that there is no changes other than the batteries have been replaced. I am an electrician and am savvy as to how to change batteries out one at a time and one wire at a time...

[cgtech]

That's odd. Unplug controller pins 2 & 3 & ohm out the wires. Should read near zero when at rest, and near 5000 ohms at full throttle. Be sure to do this test with the F&R in neutral, key off, (and one battery cable disconnected if you wanna feel super safe).

[ksmillie@yahoo.com]

I checked the Ohm on the Pedal, pins 2 & 3, 0 to 5 ohms as expected, you can see the resistance increase with the pedal depressing....next step please?
Thanks for the help!

[ksmillie@yahoo.com]

something else I cannot figure out....I have looked and looked and looked for ANY diagram that shows this yellow (i guess its a resistor) thing on my controller...connected between B+ and B- terminals, obviously it is broken and I really dont think it would make much difference on the controller working....does anyone know what it is?
Pardon the old ugly wiring....and the pins 2 &3 wires are removed in this photo for testing the pedal resistance

[kernal]

Called a varister. Similar to a diode and performs the same function. Controller should operate normally without it. Offers some protection for internal components over time. Modern carts use a diode and some Alltrax controllers have it built in internally I believe. Prolly depends on model and/or application.

[ksmillie@yahoo.com]

Ok....update, Pack voltage at 38 volts....confirmed 38 volts both side of solenoid when engaged...
38 volts to B+ and M- (grounded at pack negative)
Have cart off the ground with no load on axle, press pedal, wheels spin for a few seconds and slowly drop off, while doing this I watched the pack voltage maybe drop a .5 volt but still over 36.

[ksmillie@yahoo.com]

and another. update....pulled every cable from Batteries, FNR, and Controller and CLEANED them all and replaced.....same story, motor engages for a second and then quits.....Im almost convinced that I have a bad controller...
I swear it acts like it has a thermal cut out or something..
I placed the tester at the controller side of solenoid, voltage is 37 volts when engaged

[ksmillie@yahoo.com]

ok, finally received Alltrax 48400.....It came with a wiring diagram...I am an electronics / Electrician so, no worries there.....does the two A2 wires from the old controller (terminal A2) simply bypass the new controller and go straight to FNR switch? it looks like it on the diagram but no narrative or video to be found...