Quick question on wiring up lights.

Ok so i just installed my front bumper and starting the wiring process for my lights. I'm using this to go off of. http://www.classictruckshop.com/clubs/earlyburbs/projects/bosch/foglites.htm

Now There is a power source coming from the Batt to relay and also one from the fuse box to switch? I have eveything wired up to my relay just like the diagram. Pin 85 would be load side of my switch correct?

What does load side mean?

Do you have a seperate indicator that is not on the switch? Do you have this wired up yet?

I'm not a wiring guru, but I have set up auxilary lights, rock lights and Aurora back-up lights with minimal instruction

No seperate indicator. Indicator is built in the switch. (LED light) There are 3 pongs on the back side of the switch. Ground, load, power. I'm no lighting guru either is why i'm asking. I have everything wired to my relay just as it says in the diagram.

Ground prong = ground to body somewhere.
Load prong = comes for relay/85
Power prong = connection either to fuse box or splice into another wire.

Whats the problem?

Guess I never really understood how a relay work is all.
So the relay is powered as well as the switch. Power from the switch opens or closes the relay?

If you are not worried about a light on the switch you can wire it safer this way...It will keep the power run outside of the cab area so you do not have to worry about it shorting out if the wire gets chaffed through going through a hole in the fire wall or where ever you will have it run through to get tho the relay. And when power is run through a switch long enough if can/will get warm/hot. I have burnt/melted quite a few good quality switches before I now wire them all this way. Atleast this way if it does short out it is just the Negative(like the rest of the chassis already is) so it will not burn things up. What you are mainly doing here is controlling the Neg. side of the switch in the relay instead of the Pos. side.

and of course DO NOT forget to fuse your power wire correctly depending on lights amp draw and wire size choice. As amps are what will heat a smaller wire up if trying to feed more amps through to small a wire than it can handle.

So if the wire grounds out, the accessory kicks on? I think I'd rather stick to wiring them normally and using fused and switched power, but that's just me.
If it's wired correctly, you won't cook switches with a relay anyway.

CaliXJ said:

Now There is a power source coming from the Batt to relay and also one from the fuse box to switch?

Click to expand...

Yes. They are seperate. The + from the battery goes thru the relay and to the lights when you flip the switch. The + from the switch simply triggers the relay.

CaliXJ said:

I have eveything wired up to my relay just like the diagram. Pin 85 would be load side of my switch correct?

Click to expand...

Not sure what you mean by "load side", but yes I think you are looking at it correctly.


If you ever get a chance, open up an old relay and you will instantly understand how it works.

There are actually two circuits inside the realy. The first is an elctromagnet that is grounded through pin #86 and energized through pin #85 from your switch (which gets + from the fuse block).

The second is a set of points that are actuated by the elctromagnet. Once you flip the switch, the electromagnet pulls the contact points together and power flows directly from the battery into pin #30 through the points and out pin #87 to your lights.

HTH.... As long as you followed the schematic properly and you have fuses before the switch and before pin #30, you will have no problems.

hubs97xj said:

So if the wire grounds out, the accessory kicks on? I think I'd rather stick to wiring them normally and using fused and switched power, but that's just me.
If it's wired correctly, you won't cook switches with a relay anyway.

Click to expand...

Yes it will come on. But unlike having the pos. wire short out and spark everywhere till it pops a fuse if wired with one, the neg. wire will not heat up and melt the insulation off and have the chance of burning the Jeep to the ground. But having the switch control the neg. wire if it does chaff through it will not short anything else out. Since the chassis is neg. ground already. Keep in mind this is just to control the switch inside the relay. It also cuts down on the pos. wires running everywhere.

If it is correctly wired in a perfect world with the amp draw and wire span and wire sized right for said info, you should be ok. But any time a pos. wire is interrupted by a switch the amps that go through that particular wire do as well. Amps are what heat up the wires and or switches not the voltage that goes through it. So to be safe I have always recommended running any accessory no matter what amperage it draws, with in the limits of the relay of course, to be run this way.

I am just saying this works for me and has never let me down,ever. Doing it the other way has. I have had melted switch, wires, connectors, etc. I almost lost a whole vehicle because of it, not mine but the one I was working on(snagged a sharp piece of metal under the dash) before I did it this way.

I am not debating that anyone is right or wrong here as we all are entitled to our opinions. This is just the way that I do it. Some will agree some will not that is our choice as human beings. Just take it as another possibility to use.

Wow! Lots of great info here guys. Thanks!

One thing I would suggest is using a circuit breaker instead of a fuse. They don't cost much, will reset and can be gotten for higher amperages for some of those more powerful lights.