Series Cart Killing Pedal Micro Switches?

[TGJR]

Trying to fix a mid-2000s series cart built for offroading.

It has an Alltrax AXE-4865 controller, 200a solenoid, HD forward/reverse contactors. It wouldn't run and I was able to track the problem down to a dead pedal box micro switch. Replaced it and all was well for the first few pedal pushes under barely any load. Then dead. Voltage wasn't passing through the new OEM pedal micro switch again. So back off comes the floormat and box cover. Switch is dead just like the other one.

Is that dumb luck that the new micro switch from the EZGO dealer broke after 10 seconds or do I need to be looking at something else causing that?

[JohnnieB]

Is there a diode connected across the solenoid coil?

If not there should be.

If there is, it may be bad or installed backwards. (The banded end should connect to the small terminal with the red wire(s) on it.

[TGJR]

The diode is there and installed correctly (white line to the + post). I tested it with a multimeter (ohms) and in one direction the reading settles around 78 k ohms and in the other direction there is no continuity at all. This is with one side of the diode disconnected from the solenoid.

So I assume the diode is still good, right?

[TGJR]

I will say when I removed the broken micro switch the first time, I briefly touched the two spade terminals together to complete the activation circuit to see if the solenoid would click and it did. However, there was a good amount of blue spark coming from the brief less-than-ideal connection of the two female spade terminals touching. After killing the new micro switch, I'm wondering if that blue spark was the result of a dead short somewhere downstream.

[JohnnieB]

It's bee so long since I checked a diode with an Ohmmeter, I don't remember what a good forward bias Ohm reading is. I use the Diode check function found on most DVMs and look at the voltage drop across the junction. (About 0.5V forward and OL reverse)

The diode on the coil of a 200A solenoid out to be rated for 3A or more.

When the solenoid de-activates a huge voltage spike is generated by the collapsing magnetic field and it zaps the contacts of whichever switch that opened the circuit. The pedal switch is usually the on that opens the circuit, so it is the one that gets zapped by the solenoid the most when the diode isn't installed. However, even without a diode installed and a 200A solenoid, the pedal microswitch ought to last years, or at least months.

The spark you got when you connected the pedal switch wires together might be normal. The initial amps on the coil of a 200A solenoid is probably in the 3A to 5A range, so you could get a pretty health spark.

Might be an idea to check the solenoid coil resistance. You can probably find a spec sheet for it on-line, but if it is a SW-180, it should be 102Ω for a 36V coil or 150Ω for a 48V coil.

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Personally, I'd put in a new 1N5408 (or higher rated) diode in the coil and new pedal switch if the solenoid coil resistance was in the ballpark.

[TGJR]

I broke out another multimeter with a diode function and I am getting .5 measuring the voltage drop. No reading with the probes reversed.

Can a bad diode on either of the forward/reverse contactors cause the pedal micro to short out like a bad diode on the solenoid can?

[JohnnieB]

That diode ought to be good.

Maybe, the voltage to the toggle switch type F/R probable goes through the the pedal switch.

[TGJR]

Assuming the diodes on the F/R contactors are good, what else could kill the brand new pedal micro so fast? I did a good once over on the activation circuit wiring and could not find anything obvious that could be causing a problem.

[TGJR]

Both F/R contactor diodes also read .5 or so in one direction and nothing in the other. I guess all the diodes are good.

The owner says the cart started acting up and/or died after it was rinsed off. Being an offroad cart, I would imagine a good amount of water was used to get the dirt off.

[DanRoss]

A thought from a golf cart novice. Can you post some pictures of the switch installed and out? Maybe there is something wrong with the way it's installed and the pedal is pressing it too much causing physical damage?