Hey guys I'm a new 1989 Toyota owner and have a question about some lights that are mounted on my truck. I have 2 lights on my roll bar that were installed before I bought the truck. These lights never worked and the past owner said that the wiring went bad. I followed the wiring into the cab and it led to a switch in the dash. The wire then led through the firewall and straight to the positive terminal with only a 20 amp fuse (not blown) in between the switch and terminal. My question. Shouldn't there be a relay somewhere? Also the switch in the dash lights up. Does this mean I can assume the short is somewhere between the switch and lights? Thanks for your help

 

Do a continuity test of the wire from the switch to the lights. then switch to batt. If the wires are intact then the switch could be faulty. a relay isnt always necessary but if your pulling alot of amps i would recomend one.

 

So it sounds like the lights just went from the Battery to the switch to the lights. The correct way to wire it would be to put in a relay and have the switch control the lower amperage side of the system to operate the higher amperage light circuit. I agree with rollem, check the switch, it has most likely gone bad, it might light up but the contacts inside that send the current might be burned up. I would think, depending on the size of the lights that a 20 amp fuse might be low and would blow in this circuit. Watts/Volts=Amps so if you have 2 120 watt lights, you are good 240 Watts / 12 Volts = 20 Amps.

 

have you checked your ground wire yet? it sounds about like the same problem i had with mine, they didnt get grounded properly so the little switch light worked, but the 2 daylighters didnt.

 

Alright thanks for the input. I'll do a continuity test first thing in the morning and let you know how it goes.

 

id rip it all out start over it should be wired to a relay

 

I think I'm going to redo the wiring entirely and wire it through the brights when payday comes around. Anyone got a Good wiring diagram. I think KC lights have one on their website i'll check

 

Wiring them isnt rocket science (unless James Woods is doing it) so you shouldnt need a wiring diagram. If you want to drive them with your high beams (not really recommended but it is your truck) all you need to do is tap off the headlight feed up front by the lights (battery side preferably) and use that to activate a simple relay (terminal 85) and give the other side of that coil (terminal 86) a ground. Pickup power from the battery, through a 20amp fuse and route it to one side of the relay (terminal 87) and feed the other side out to your lights (terminal 30).

 

Depending on the lights, and if you don't plan on adding any more you may not need to bother with a relay..
As long as the switch, fuse, and wire are sufficient, why not keep things simple?

 

Well I'm thinkin about incorporating a 3way switch offering on/brights/off. I live in pretty rural area so I will be fine using them with my brights most of the time. For now though the roll bar that they are wired through is not budging. I PB'd the bolts and will keep trying till they break free. Definitely time for some new bolts back there. Until then I wont have access to the wiring. I'll keep you'll posted. Thanks for the Help!

 

all he did was show Ohm's law

OP-if you tap the headlight wiring for power..solder it, don't use one of those crimping taps..it will cause issues down the road.

 

It may be simple but the more amps that you run through the switch will shorten its life, when you have 2 copper contacts that switch power, it is going to arc and burn a little off, kinda like the electrode on spark plugs gets shorter. So to prolong the life of the switch, you would install it on the low amperage side.

Its not rocket science, just engineering, figures since I am going to school for it. Also to make the relay last extra long, you could also install it onto the ground side of the lights instead of the power side, so all it does it provide the ground for the lights, but you can just wire it up just like quoted above, not hard at all Google how relays work and it will all make sense. Then draw out your own wiring diagram.