# light wiring problems



## bristolturf (Dec 20, 2008)

ok so I took these lights that were on my salt spreader that plugged into the trailer hookup off the spreader and ran them so they would have a switch and not plug into the trailer harness. These are mounted under the rear bumper for extra lighting in back. 

I went to walmart and just bought a cheap switch, and some extra wire. I first ran the switch, one to the positive terminal and then grounded the switch to a piece of metal under the dash. Next I mounted the lights and grounded them each individually to a piece of steel under the truck. Next I ran the left side light to the switch in front of the truck, I then ran the right side wire to the leftsides wire connected the two. Went to the truck flipped the switch and nothing. I thought maybe i had a bad ground tried 3 different spots and still nothing. Any ideas on what could be wrong?


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## 20Silverado05 (Jan 16, 2008)

Did you use a fuse for the wire to the battery before the switch? 

If you have a multimeter then check to see if you have source battery voltage at the lights power wire with the positive lead at the lights power wire and the negative lead at the battery negative. If you read 12volts or near then try to see if your ground is good by moving the lead from the negative terminal to the lights grounds.


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## bristolturf (Dec 20, 2008)

what i also tried doing just to see was running a wire directly to the battery and seeing if the lights powered up but nothing .


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## 20Silverado05 (Jan 16, 2008)

bristolturf;934850 said:


> what i also tried doing just to see was running a wire directly to the battery and seeing if the lights powered up but nothing .


did you run just a power wire or both power and ground to see if it would power up?


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## SafetyLighting (Jul 23, 2005)

bristolturf;934819 said:


> Any ideas on what could be wrong?


So as previously asked, did you fuse the power feed at the battery? What size wire are you using and what type of switch and what is it's power rating? Start at the battery and work your way towards the lights with a meter. What type of lights are they?


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## bristolturf (Dec 20, 2008)

yes there is a fuse on the power wire (wire from the switch to the battery). Wire size is 16 or 14, i cant remember off the top of my head. And i will have to get back to you on switch type and rating, it was just some plain switch from walmart that i picked up, nothing fancy.


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## SafetyLighting (Jul 23, 2005)

ok, just be be clear, where exactly is the fuse? Is it right at the battery?


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## bristolturf (Dec 20, 2008)

its connected to the terminal then about a foot of wire then the fuse then its ran to the switch


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## SafetyLighting (Jul 23, 2005)

Ok good, just wanted to make sure. You really need a multimeter or at least a test light. How many terminals are on the switch?


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## bristolturf (Dec 20, 2008)

three, one connects the ground wire, another connects the power wire, and the other connects the accessory


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## SafetyLighting (Jul 23, 2005)

ok, well, when you turn the switch on, does it light up?


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## festerw (Sep 25, 2003)

Sounds to me like the ground you've got on the lights is the problem, did you clean a spot on the steel where you grounded or just run a screw in?


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## bristolturf (Dec 20, 2008)

then i have a multimeter, but i really dont know much about using it. where do i connect each end to so that i get a reading. I am really no expert in electric so I dont know how to do these things nor do i know how to actually even read a multimeter so if you could better explain that would be great.


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## bristolturf (Dec 20, 2008)

yup i took a screw driver and cleaned the rust off the steel for the ground.


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## bristolturf (Dec 20, 2008)

and no the light on the switch doesnt light up when i turn it on


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## festerw (Sep 25, 2003)

On the multi tester, turn it on to the ohm setting, touch the leads together to check you've got it on the right setting and it should go to 0
Connect one lead to one wire of your lights
Touch the other to your ground, if it goes to 0 your all set if it doesn't you've got a bad light or a bad ground I'm guessing a bad ground the metal where you've grounded it to should be clean and shiny sandpaper works well.

Now switch the meter to the DC volts setting something above 12 if your meter has different ranges. Connect the red lead to the + battery post and black to the - to test you should get 12.xx volts on the screen.
Go under the dash and connect the red lead to the wire you've got coming from the battery and black to your ground, you should see the 12.xx volts again
If you don't see 12.xx volts you have a bad connection between the battery and switch check the fuse first and verify you have the wire hooked to the 'supply' terminal of the switch and the wire going to the lights hooked to the 'load' terminal.


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## SafetyLighting (Jul 23, 2005)

well, if the switch isn't working, then the lights probably won't work either.


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## bristolturf (Dec 20, 2008)

ya i know that, but what was weird was when i ran a wire straight to the bat from the lights just to test them they didnt work either. So i dont really know whats going on with them. I will try that. My multimeter is old tho haha, its not digital its got the pointer and like 100000 things on the screen.


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## festerw (Sep 25, 2003)

The power straight from the batter to the lights is why I suggested you clean up the grounds a little more. FWIW you can get a digital meter from wally world or harbor freight for under $10 that will do what you need it to.


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## Too Stroked (Jan 1, 2010)

A simple test light would probably be all you need here instead of buying a multi-meter. What you're trying to find out is if and where you have power. A test light simply needs a good ground to help you find power - if it's there at all. 

Another problem you might have is incorrectly wiring the switch - if it happens to be a lighted switch. Does your swithch have two or three connections on it? (If it has just two, disregard this whole paragraph.) If it has three, it should have a legend either molded into the case or on a sticker on the side. On lug should be from your fused / hot lead. Another should go to your lights and the third should be a ground. Get this mixed up and you won't get power where you need it. 

Another silly thought. Did you fuse blow along the way due to a problem? Your wire diameter sounds a little light and we don't even know how many amps your lights are drawing yet. If it blew right away, that would explain a few things and I've seen far stranger things happen. 

And finally, remember the advice a wise Service Manager taught me many years ago: "Almost all weird electrical problems are a bad ground."


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## Pirsch (Jun 1, 2007)

I see a couple problems... Your switch can't handle the draw... Go to an auto parts store and buy a push pull switch like in the old headlights. Get something that will last. Since your using Walmart parts/pieces... Those connectors are trash. You need to make sure that your main grounds... are all connecting to the body. Even if it's a newer truck you still have some coating that you have to go through to get good contact. My suggestion...on your main grounds drill a new hole and put a steel bolt and then silcone the top of the bolt/connector. Biggest problem is the switch by far!

Good Luck


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## festerw (Sep 25, 2003)

Pirsch;936776 said:


> I see a couple problems... Your switch can't handle the draw... Go to an auto parts store and buy a push pull switch like in the old headlights. Get something that will last. Since your using Walmart parts/pieces... Those connectors are trash. You need to make sure that your main grounds... are all connecting to the body. Even if it's a newer truck you still have some coating that you have to go through to get good contact. My suggestion...on your main grounds drill a new hole and put a steel bolt and then silcone the top of the bolt/connector. Biggest problem is the switch by far!
> 
> Good Luck


I'll agree but disagree, the switch is a problem running as it's currently hooked up, it would be fine if run with a relay. That is the way I prefer since you can run any switch you like. The connectors he's using are probably fine since they're probably using crimp connectors and not the scotch lok's.

IMO here's what you need to do bristol. Get a roll of 12 gauge black and red, a relay, a package of female spade connectors, a package of ring terminals to fit the battery connector, package of butt connectors and a can of liquid electrical tape. 
Run red 12 gauge with a fuse from the + battery to pin 30 on the relay
Run red 12 gauge from pin 87 to the lights
Run black 12 gauge from pin 85 to the - battery
Run some of your 16 gauge wiring from the 'load' terminal of the switch to pin 86
Run 16 gauge from the 'supply' terminal to a switched 12v source under the dash
Run 16 gauge from the ground terminal to a clean source under the dash.
Connect both lights to the red 12 gauge at the back
Clean up your light grounds and reconnect them
Seal all of the connectors with the liquid electrical tape.

That way you take all of the load off of the switch, you can't accidentally leave the lights on and you'll get plenty of power to the lights.


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## SafetyLighting (Jul 23, 2005)

> Get a roll of 12 gauge black and red.


So then you must know what the current draw of the lights are.


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## festerw (Sep 25, 2003)

SafetyLighting;936865 said:


> festerw;936823 said:
> 
> 
> > Get a roll of 12 gauge black and red.
> ...


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## SafetyLighting (Jul 23, 2005)

Oh ok, I am still waiting to hear from the OP on what type of lights, so we can figure out exaclt what the electrical ratings are. Tough to lay out the whole system properly without all the info.


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## bristolturf (Dec 20, 2008)

not exactaly sure on the type of lights, they are off of my buyers tailgate salt spreader, they came on the unit when i purchased it. And they are just the standard round lights


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## festerw (Sep 25, 2003)

That what I figured amp draw should be between 3-5 amps per light, depending on 35 or 55 watt.


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## SafetyLighting (Jul 23, 2005)

Ok, so then each light will draw about 5 amps a piece. 14 gauge wire will handle the current just fine. Your switch would need to be able to handle 10 amps or you will need to use a relay. The fuse at the battery should be a 10 amp fuse. For the best possible ground, use a factory ground locations.


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## bristolturf (Dec 20, 2008)

ok is the fuse in the right spot near the battery or should it be near the switch? I would assume it wouldnt matter really, but I just want to double check. I probably will use a relay, and rewire it that way. I had my friend look at it and he messed around with a bunch of wires and now has like 100 splices in the thing so I will rewire it with either 12 or 14g and use a relay. Just a 12v 4 way relay correct?


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## festerw (Sep 25, 2003)

Fuse should be as close to the battery as possible, just a standard relay will work doesn't matter if it has 4 or 5 terminals. Good idea to use the relay and heavier wiring as it will make it easier if you want to add more or brighter lights in the future.

Something like this
http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_RELAY-LITE-30-AMP-HD-Night-Blaster_6250513-P_N3443_A%7CGRP2044____


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## SafetyLighting (Jul 23, 2005)

It definitely needs to be at the battery. A fuse ony protects what is downline. So if the fuse was at the switch, it wouldn't protect the wiring from the battery to the switch. If there was a short, you would have some serious issues.

I'm going to draw you a schematic. A picture is worth a thousand words.


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## bristolturf (Dec 20, 2008)

a picture would be very helpful. I am just having trouble understanding a few things n this, such as running from 87 to the lights then running from the supply to a switch 12v source under the dash. So if those are answered i think i will be good.


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## SafetyLighting (Jul 23, 2005)

Here is a basic CAD drawing.

http://www.safetylightingandequipment.com/Public Uploads/Light Schematic.pdf

It's not to scale obviously, LOLOL.


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## bristolturf (Dec 20, 2008)

Ok so i want to make sure i understand this correct both the load and the supply go to the relay from the switch? I connect both the supply and the battery + cable to the 30 on the relay. Should i connect the wires together and have only one wire on the relay or connect each individually?


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## SafetyLighting (Jul 23, 2005)

Both the relay and the switch need to have a positive battery feed. You can run two seperate wires from the battery if you want, or use the same wire. It doesn't matter either way.


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## festerw (Sep 25, 2003)

That's a great diagram, I may have to borrow that one.

bristol on the bottom of the relay all the terminals will be numbered and the numbers don't change across brand names so you get 
30 is the 12v+
85 is the 12v+ to activate the relay
86 is the ground
87 goes 12v+ when the relay is activated
87a is 12v+ when the relay is inactive.
Pins 85 and 86 can be reversed with no harm since they are just a coil.

On your switch there will be 3 terminals, one will be the ground, one is the 12v+ supply(power input) and one is the 12v+ load (power output


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## SafetyLighting (Jul 23, 2005)

You can use it freely. I'm definitely a beginner, but ACAD is awesome.


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## festerw (Sep 25, 2003)

bristolturf;937273 said:


> Ok so i want to make sure i understand this correct both the load and the supply go to the relay from the switch? I connect both the supply and the battery + cable to the 30 on the relay. Should i connect the wires together and have only one wire on the relay or connect each individually?


The load from the switch will go to pin 85, the supply on the switch can get power from pin 30 or the battery if you want to be able to turn the lights on whether the truck is running or not.

You can also connect the supply from the switch to a wire inside the cab if you want the lights to only be powered when the truck is running.


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## festerw (Sep 25, 2003)

SafetyLighting;937297 said:


> You can use it freely. I'm definitely a beginner, but ACAD is awesome.


It looks great compared to some of the diagrams I've made in MS paint, maybe I'd do better with finger paint


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## Too Stroked (Jan 1, 2010)

SafetyLighting;937282 said:


> Both the relay and the switch need to have a positive battery feed. You can run two seperate wires from the battery if you want, or use the same wire. It doesn't matter either way.


Isn't it true that although you need two positive leads to the realy, one is a high current draw (generally hooked to the battery) and the other one is a lower current draw (what I sometimes call the "trigger" side) and can come from a properly selected fuse in the interior?


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## festerw (Sep 25, 2003)

That is correct, no way is wrong as long as it's fused.


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