EZGO smoking resistor

[cartemoff]

Ok, I am new here to the forum and I appear to have quite a confusing issue. 2002 EZGO 36V with Series motor. Original issue began while driving the cart with some weight on it (280 lb buddy, myself and two nice sized hogs - the wild four legged kind...). The cart suddenly went from normal operation to the throttle was either wide open or off. In other words if I barely touch the pedal it would react with full throttle.

Got off and lifted the seat to see the resistor between the two large lugs on the Solenoid smoking and hotter than a firecracker.

Brought the cart back to the shop and pulled the solenoid, had it tested at Autozone and they found it bad. Bought a new one put it on and plugged up the charger and near-immediately the Resistor started smoking again.

Any ideas on where to start troubleshooting from here??? I am at a loss.

[cgtech]

I think your controller is history.

[scottyb]

Originally Posted by cartemoff

Ok, I am new here to the forum and I appear to have quite a confusing issue. 2002 EZGO 36V with Series motor. Original issue began while driving the cart with some weight on it (280 lb buddy, myself and two nice sized hogs - the wild four legged kind...). The cart suddenly went from normal operation to the throttle was either wide open or off. In other words if I barely touch the pedal it would react with full throttle.

Got off and lifted the seat to see the resistor between the two large lugs on the Solenoid smoking and hotter than a firecracker.

Brought the cart back to the shop and pulled the solenoid, had it tested at Autozone and they found it bad. Bought a new one put it on and plugged up the charger and near-immediately the Resistor started smoking again.

Any ideas on where to start troubleshooting from here??? I am at a loss.

I'm not sure what the problem is but I have never heard of an Automotive Store that had 36v to test a solenoid coil with oooor had a 36v constant duty golf cart replacement solenoid on the shelf? You either have the best Autozone or somethings wrong...

[radioman]

Make sure you have a solenoid with a 36 volt coil. Like scottyb mentions, most auto parts have no way of testing a 12 volt coil solenoid. The original solenoid was probably ok or cart would not have moved at all. You need to get yourself a voltmeter and avail yourself to a world of information and schematics available on this site and study them if you are going to work on electric golf carts. The resistor is getting hot because for some reason the controller drawing current when it should not. Suspect controller is bad and you may have the wrong voltage solenoid installed which get hot when energized and add to the trouble and confusion you already have. Ask you parts store what voltage they used to check the solenoid. You should get it back before they can it if you didn't bring it back with you.

[cartemoff]

Probably should clarify - Autozone tested the solenoid, seemed legit, and their findings seemed to support what I had tested based on information I had read from the site here. But I went to an EZGO dealer to pick up the new Solenoid (White Rodgers 586-117111).

One important note of concern to me: in testing from the Battery Negative (battery #6 in the series neg terminal) to the B- I get continuity, no surprise. But also when testing from Battery Neg to B+ I also get continuity, which alarms me. From all of the diagrams I have looked at, and I have looked at quite a number of them on here, I don't believe I should be seeing continuity between Battery Neg and B+, should I?

[radioman]

No. You need to disconnect the battery negative and make some resistance measurements from the wire removed form the battery negative B- to various points. Continuity can be misleading. You need accurately make some resistance measurements to determine where and to what extent you may have a low resistance or near continuity. This can get confusing. Maybe some other posters can help you too. There are a lot more knowledgeable golf cart mechanics than myself here willing to help. Don't try to second guess what may be wrong with a electric golf cart. Scientific analysis is required.

[cartemoff]

I guess the one thing that is puzzling me and keeping me from thinking that the Controller is the likely culprit, is that I can't see how plugging the charger in would invoke the "Speed Controller" and cause the Resistor to start smoking. It seems, again from my over-studying of so many wiring diagrams, that the charging system should bypass the speed controller while charging the batteries. I called one of the local EZGO dealers and spoke to one of their techs, he was eager to help me talk through the likely issue and he mentioned that he would start chasing the ITS as he feels that there is possibly a short somewhere in that mechanism or its wiring. Does this sound plausible? Just curious before I start pulling the flooring apart to get to the ITS. And is there a good script for troubleshooting the ITS by chance?

[JohnnieB]

Originally Posted by cartemoff

I guess the one thing that is puzzling me and keeping me from thinking that the Controller is the likely culprit, is that I can't see how plugging the charger in would invoke the "Speed Controller" and cause the Resistor to start smoking. It seems, again from my over-studying of so many wiring diagrams, that the charging system should bypass the speed controller while charging the batteries. I called one of the local EZGO dealers and spoke to one of their techs, he was eager to help me talk through the likely issue and he mentioned that he would start chasing the ITS as he feels that there is possibly a short somewhere in that mechanism or its wiring. Does this sound plausible? Just curious before I start pulling the flooring apart to get to the ITS. And is there a good script for troubleshooting the ITS by chance?

If anything, plugging in the charger would disable the speed controller (That is the intended purpose of the Reed switch), so I suspect the pre-charge resistor getting hot in conjunction with the charger being plugged in was either coincidental, or the charger simply upped the pack voltage enough to make the resistor smoke.

The original symptoms tells me that the solenoid is good and the MOSFETs in controller are either shorted or being told to conduct. When the solenoid's contacts are closed, the motor runs at high speed, but when the solenoid contacts are open, the resistor gets hot because the motor is trying to draw the amps it wants through the resistor instead of through the closed solenoid contacts.

Jack the rear wheels off ground and put on jackstands so cart does run over someone or something.

Disconnect battery pack from solenoid. Remove cables from B- and M- terminals on controller. Unplug molex connector on top of controller.

Wait 5 minutes for filter capacitors to discharge. Measure between B+ and B- terminals with voltmeter to be sure.
When the voltage is zero, measure the conductivity between the B- and M- terminals.
Should conduct in one direction, but not the other.
If you have conductivity in both directions, the controller is bad.

If you do get conductivity in one direction only, it might be an ITS issue.

[cartemoff]

Ok, I will try that and see what I can determine. The one question though: I don't have any Molex connectors on my Controller. I have 4 large lugs (M-, B-, B+, and A2) and then I have 4 small (1, 2, 3, and an unlabeled) photo attached of mine as wells as stock photo without any of the wires on it. I have had one heck of a time finding a stock photo, so I fear that this controller might be semi-rare or expensive to replace... My question though, is do I disconnect all but the B+ and A2 cables? In other words, in absence of a Molex connector, I assume I should disconnect all 4 of the small wires, right?

[JohnnieB]

The most common 2002 with a series motor is a TXT body style with a Curtis 1206 controller (275A), which has the four control wires bundled in a molex connector. Looks like you have the heavy-duty controller - Curtis 1205-117 (400A ITS throttle). (Might be a label on the bottom or back of unit)

Not as widespread usage as the 1206, but pricing is about the same.

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You are correct, just remove the four control wires - but mark them first, so you can put back in the right places.

Other that that, the test is the same.

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If it is bad, FSIP (One of the BGW site sponsors) sells them New and Refurbished. http://www.fsip.biz/NewGolfCurtis.html

Or you could replace it with an aftermarket one: http://www.cartsunlimited.net/Custom_Options.html