headlight relays for h4 harness upgrade

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Feb 17, 2016 | 12:38 PM
  #16  
Quote: The picture I linked is of my exact harness and it uses standard sized bosch relays, so if one fails I can replace it. The relays in the harness he linked are the same size/style, so if they fail he can replace both with a standard 5 pin 87/87a relay and it will work exactly the same because pin 5 (87a) on relay A (4pin relay) is not wired to anything. But, you can buy both 4 and 5 pin relays at any parts store, just check the diagrams on the relays themselves and reference this:

http://www.accessconnect.com/car_relays.htm
My point was that with the Putco harness that uses two identical relays, if the low beam relay goes out at night, I can swap the high beam relay into the low beam spot and then I have headlights again. And relays are only stout if they don't get moisture in them. That's where the cheap Chinese relays differ from the ones you get at a parts store.
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Feb 17, 2016 | 12:48 PM
  #17  
Quote: I read everything, thanks a bunch guys. I'll wait till I receive the harness to figure out the actual setup. Relays are rated 12v/40A so I'm guessing I shouldn't go above 40A. As suggested I'll just install everything and then see what my next move is. I would probably still order some spare relays in case one (or both) fail. The purpose of this thread was basically so I could be prepared in the event I lose power to my lights while it's dark outside.
Depending on what is stamped on the relay the 40A could be for the ratings on the contacts basically stating that you should not run more than 40A through the contacts or the 40A could be for the coil on the relay this is what makes the contacts move internally. Just keep it simple and don't over fuse anything and it should be fine.
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Feb 17, 2016 | 02:05 PM
  #18  
Quote: My point was that with the Putco harness that uses two identical relays, if the low beam relay goes out at night, I can swap the high beam relay into the low beam spot and then I have headlights again. And relays are only stout if they don't get moisture in them. That's where the cheap Chinese relays differ from the ones you get at a parts store.
Ya but the putco harness is wired differently than the others, its using a different style of relay and if you notice it's basically 2 circuits, one for lows, one for highs. The other style is wired as basically a 3 way switch, so yes if one relay goes out I will have no lights.
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Feb 17, 2016 | 02:10 PM
  #19  
Quote: Ya but the putco harness is wired differently than the others, its using a different style of relay and if you notice it's basically 2 circuits, one for lows, one for highs. The other style is wired as basically a 3 way switch, so yes if one relay goes out I will have no lights.
...I know, that's exactly what I was saying.
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Feb 17, 2016 | 02:24 PM
  #20  
I see what you mean, I could pretty easily rewire mine, but the odds of a relay failing are pretty slim, unless I dunk my Jeep in a river, and I'm comfortable with those odds.
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