No headlights and odd electrical behavior

FoothillTom

Howdy folks, I have a 1993 Club Car DS that I've owned for 6 years (I'm the 2nd owner). It's completely unmodified. I have a little electrical mystery here that I'm hoping you folks can assist me with.

Over the past year or so, on a few occasions, we noted the headlamp switch did NOT activate the lights. Being the brilliant diagnostic technician that I am, I pressed the "brights" foot switch and whammo! the lights came on. This behavior was intermittent and the lights operated correctly more often than not with just the basic operation of the headlamp switch. In fact, the lights were fine just yesterday.

I was not aware of any other electrical oddity until last night.

Fast forward to last night, the lights would not come on at all, despite the little game with the bright switch. I'm pretty comfortable with my multi-meter (I restore old cars as a hobby) and started measuring voltage on various switches.

I started with the headlamp switch itself. There are 2 wires (brown and orange if memory serves) on one side of the switch and a yellow on the other.

I measured 12V on each of those 2 wires to a good ground. Oddly, I measured 12V across the switch itself in the OFF position, and 0V in the ON position. As my mama raised no dummy, I suspected the switch and removed it. I then tested for continuity across the switch. There was continuity in the OFF position, and there was no continuity at all in the ON position (totally backwards)! I thought I had my suspect but this is where things get weird for me.

To prove the bogus switch theory, I connected the 2 12V headlamp wires with the yellow (what I suspected was ground) wire to see if the lights would operate. To my layman's way of thinking, I was essentially removing the switch with this little exercise. But no lights! Not even a spark. I was baffled.

I re-installed the switch and measured voltage on other things and this is what I found:

* 12V measured on each of the 2 fuse links in the OFF position
* 24V measured on each of the 2 fuse links in the ON position (weird!)
* Clock operates fine in OFF position
* Clock stops in ON position (I was anticipating some kind of time travel at this point)

I started to suspect the brights foot switch since it was part of my odd work-around a year ago. I measured 12V on each of the 3 wires going to that switch (blue, orange, and yellow). What the heck? I removed the switch and checked for continuity across each of the 3 terminals and found no continuity across any combination. I then thought perhaps this switch was bad but then gave up for the night as there were just too many mysteries here.

I've never worked on an electric vehicle before and this one already seems to defy what I thought I knew about 12V circuits and switches.

Oh, and final thoughts:

* The horn (another foot switch) is also not working...have no idea if this is coincident with lights, but am assuming so.

* Brake lights not working...I'm pretty certain they worked yesterday.

* Both fuses are good

* Cart charges and drives just dandy otherwise

Sorry for the long post, but I figured I'd err on the side of detailed.

Thanks!
Tom

BGW

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DOOmsman

Not a sparkler man but a lot of what you describe points to a weak ground connection.

shadowman

ok you have a 36 volt cart i only understand that because its a 1993.......as for your problem i didn,t understand a word you typed, lift the seat and find the 2 batteries the lights are hooked to and make sure all is good.....clean,tight didn,t break than check power and ground right at the lights where they are connected if you have power to the lights themselves than it has to be from there to switch or switch but if horn works from different switch i think your problem is gonna be a broken wire somewheres along the line unless somehow they are all hooked to the same switch........if this is a basic 36 volt cart it shouldn,t be real hard to find the problem.............

FoothillTom

Ok, I shall consider my first post to be total non-sense as hard as I tried to make sense of all this.

I would really appreciate it if you could stick with me on this as things are looking up, but there's still one lingering mystery.

Recall that I had some intermittent issues with the headlights long ago that seemed to go away by clicking the foot-switch for the brights. At that time, all other circuits were just fine...until last night when lots of stuff went out, including the horn, tail/brake lights, and my clock.

Following shadowmans advice, I looked under the bench and DANG if there wasn't a broken wire (looks like acid wore through it) from one of the batteries connecting 2 black wires that disappear into a wiring harness. Huzzah. So i repaired that connection and the horn and tail lights are now operational! So that definitely rules out the headlamp switch as a problem since the tail lights come on with the switch. However, the headlights still do not work and now I fully suspect my foot-switch since it was involved in the intermittent behavior I described earlier.

So here's my (hopefully more sensible question):

How does one test if the brights-foot-switch is working? There are 3 connections to it. A yellow wire (let's say the left side of the switch) has 12V on it. An orange (middle of the switch) has 24V. The right-most blue wire has 12V on it.

What's so strange for me is these switches are apparently designed to result in 0V in the "activated" position. Is this making any sense? Am I smoking crack here? I thought a switch resulting in voltage across its poles when closed/activated, yet these cart switches seem to work the opposite (resulting in 0V across the poles when pressed). I verified this with my working horn switch: there is 12V across those poles when the switch is "open". When pressing the horn, the voltage across the poles drops to 0V and the horn sounds.

Anyway, if somebody could please weigh in on a diagnostic for the foot-switch, I'd be most grateful. And any validation/explanation on what I'm observing with my volt-meter on these switches would also be most appreciated.

Hoping at least one word of this made sense.

Tom

shadowman

i wonder if the switch has an internal short??? the voltages make no sense the 24 volts anyways.............its a 12 volt switch and should be powered off of 2 six volt batteries giving you 12 volts but 24 volts????? i,m not an elec. guru and i,m not one for really just swapping parts but since the switch should be cheap enough i think i would grab one to at least try...................someone with more knowledge about it should be around here soon............................

FoothillTom

Agreed...the part is only $12 and I decided to order one online just now. I'll keep you posted. And yes indeed, I was surprised to see 24V on that switch, but I'm finding that this cart is nothing like the simple 12V systems on my old cars.

Thanks again for your help.

Stevegrmich

simple man

Your switches should measure " 0 " volts across the terminals when they are on. There is now a complete circuit and you are measuring 0 voltage drop ( a good thing ) The only reason I can think of for a 24V reading is that you put your negative probe on a different battery negative, than the 12V light tap is running from. All your lights should be hooked to two 6V batteries in series. The + for the 12V on one battery and the - for the 12V on another battery. These two batteries will be connected in series ( + to - ) There will be several small ( 12 - 10ga ) wires for a negative connection for your 12V accessories. You probably have another one that has broken also. I'd check around where you found the first bad wire and you'll probably find more!

I forgot to mention, the dimmer switches do go bad, as they get dirt and water over time. It wouldn't hurt to replace it and the connectors, if they look at all corroded! :)

quikbike

Volt meter measures differences in circuits. So when the switch is closed(off) you will see 12V across the poles. When the switch is open(on) you will see no voltage differential across the poles hence the 0 voltage reading.

DOOmsman

That reads wrong to me???