EZ-GO 14v On Controller Solenoid

[mauimark]

I have an old 1991 EZ-GO Cart that I have been doing a lot of work on. It all started with a spun hub, but this baby who owed me nothing, is now getting payback with failure after failure in the repair stage! (Blame the mechanic...)

So here we are today:

Wheels will spin when jacked up on stands. Will not move on ground.

In testing, I have full pack voltage at the battery-side of solenoid. 14 or so v at the controller side without touching throttle (voltage variation on pack SOC). Full pack less a fraction of a volt when solenoid engages from throttle.

Resistor tests .250 when off or on the solenoid on meter.

What do you guys think?

[JohnnieB]

Originally Posted by mauimark

I have an old 1991 EZ-GO Cart that I have been doing a lot of work on. It all started with a spun hub, but this baby who owed me nothing, is now getting payback with failure after failure in the repair stage! (Blame the mechanic...)

So here we are today:

Wheels will spin when jacked up on stands. Will not move on ground.

In testing, I have full pack voltage at the battery-side of solenoid. 14 or so v at the controller side without touching throttle (voltage variation on pack SOC). Full pack less a fraction of a volt when solenoid engages from throttle.

Resistor tests .250 when off or on the solenoid on meter.

What do you guys think?

When the solenoid contacts are open, you should get about 3V to 5V less than full pack voltage, so getting only 14V means the filter capacitors inside the controller are drawing more current than they should be, or something else is.

The nominal value for the pre-charge resistor is 250Ω. Perhaps you are reading 0.250 Kilo-ohms.

Leave the resistor off for the time being. It isn't needed to run or troubleshoot the cart. (Its purpose it to prolong the solenoid contact's lifespan)

[mauimark]

Thanks for that info. So, it isn't the resistor, because the cart actually ran for the first time in 14 months; I drove it a mile yesterday.

Today, however it wouldn't start without many tries - but once it got going - after a few false jerky starts - again, once it ran, it ran without any problem, start and stop plenty. I believe that was the same issue yesterday that had me looking at the resistor, because same thing - when messing with resistor for a while it finally lurched a few times, then started running without issue.

So, where should I be looking for the getting going issue? I did have the motor apart twice in the past two months and gave it a very simple cleaning (brushed out accumulated brush carbon...brushes are 80% worn...) the first time, and replaced a set of insulators since I broke one on one post. I saw nothing inside there that would indicate it should stick, it looked incredible for a 1991 motor after the carbon was removed.

Unrelated - what kind of oil should I have in the differential? I had gear oil for about a mile, but drained it and put in regular engine oil after reading. Just want to make sure I have the right oil in it now.

Thanks for the help!

[JohnnieB]

Sorta sounds like some corroded contacts in the solenoid or F/R switch, but might be dirty contacts in the pot box and could be other things also.
(Setting for an extended period of time in salty sea air isn't good for contacts. )

Just to be sure I'm looking at the right schematic, you have a 1991 Marathon with a speed controller?

If so, connect your DVM between the B- and B+ terminals on the controller and measure the voltage when the cart tries to move.

What does voltage drop to?

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For some mysterious reason, EZGO uses oil formulated to lubricate internal combustion engines to lubricate gears, which have different lubrication needs. The closest my electric cart ever gets to an internal combustion engine is when I park in next to my riding lawnmower in the garage, so I use gear oil to lubricate its gears.

As you see on the attached chart, SAE-85W gear oil has about the same viscosity as SAE-30 motor oil.

Bottom line is that if the cart is relatively stock, it probably doesn't matter very much if you use motor oil or gear oil, as long as you change it periodically. (IE: about every 5 years.)

[mauimark]

It's and XT-500 Turf Cart.

I cleaned all exposed (external) contacts very thoroughly. Batteries, post connections to motor, 4 posts of F/R switch, solenoid, pot box. Shiny clean, and Noalox too.

Are you thinking internal contacts? Can the solenoid be disassembled?

[JohnnieB]

Basically, it is a Marathon with a diamond plate body and a dump bed.

Is it a Resistor drive, or does it have an electronic speed controller?

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Did you disassemble the F/R switch and clean the stationary and movable contacts?

The solenoid probably cannot be taken apart.

[mauimark]

Electronic speed controller. I'm in the middle of cleaning the internal F/R switch. Taking it all the way down and cleaning every last bit, including nuts and washers (which I did with all external contacts - mostly new nuts and washers.)

Also, in testing the microswitches (they look good) it appears to me that one microswitch is solely for the reverse buzzer, is that correct?

[cgtech]

That low reading through the resistor only is concerning (like a possible failing controller). But the "solenoid output" voltage dropping to almost nothing sure looks like a bad solenoid to me. The "small silver can" solenoids are known for their ability to fail. That you can "mess with" the resistor to get it to work reinforces my beilef that the solenoid is failed.

[mauimark]

OK, so I cleaned the F/R switch like it has never been cleaned before! I answered my question myself about the second mircroswitch (yeah, just for reverse buzzer.)

So I still had the problem when I started her up right after cleaning F/R - maybe solenoid?

I just got a later model EZ-GO DCS today - it needs batteries, and possibly a controller - I think it's late 90's if the serial number first two digits is right - can I swap solenoid out of that guy to see if it works in the older cart, are they interchangeable?

[cgtech]

Yes, try that. They are the same. If the new solenoid has a diode on the small posts, leave it off for testing 'till you are sure which way to put it (silver band to + post).