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Re-wiring with relays

TjCool

New Member
Joined
Oct 19, 2018
Messages
7
Location
Los Angeles, CA
Hi Guys! Finally posting my first thread (I know... I don't have a good answer on why). Any way, I've done a few DIY projects on my 2003 Jeep 2-door and now I'm moving to the wiring aspect of it. Looking for the right way or proper way installing the proper relays and gauge wire for my winch, lights (fog and addt'l ones) with a 2.4l engine. And other extras I can use relay setup for or should use. This will also be a DIY re-wiring attempt. (I'm also a beginner at this). Thanks!
 

Necro

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Jun 22, 2022
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87
Location
Norfolk Virginia
Hi Guys! Finally posting my first thread (I know... I don't have a good answer on why). Any way, I've done a few DIY projects on my 2003 Jeep 2-door and now I'm moving to the wiring aspect of it. Looking for the right way or proper way installing the proper relays and gauge wire for my winch, lights (fog and addt'l ones) with a 2.4l engine. And other extras I can use relay setup for or should use. This will also be a DIY re-wiring attempt. (I'm also a beginner at this). Thanks!

Most winches come with the wiring that they should be used with. Use the wiring they come with or larger. Always use the same size wire or larger whenever hooking up anything electrical, the longer the run the thicker the wire. Be careful of the cheap wire brands because they will try to pass skinny wire off as thicker wire by increasing the insulation and not the wire itself. Fog lights should be wired with a relay that turns them off when you turn on your high beams. If your Jeep has factory fog light wiring it's already set up like that. If not you can wire up without doing that, but some states will fail your safety inspection because of it. Fog lights should also be below the headlights to be legal. Relay hook up is post 30 is the input. Post 87 and 87a are the output but one is at rest and the other is switched. If all you want to do is turn something on, use the switched not the at rest, if you want to turn something off wire to at rest and when switched it will go off. 85 and 86 are the coil. 1 should be hot, the other negative. I perfer to run the negative side through the firewall to a switch then the other side of the switch to ground, that way if the wire ever shorts out going through the firewall the worst case is something turns on instead of possibly burning up a wire. It doesn't matter which you use for hot or negative on 85/86 as long as you use the opposite on the other side. This is super basic info, to get you started. Google search will pull up wiring diagrams for relays. Use the search Bosh 12 volt 15 amp relay wiring.
 
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TNHEADDUCK

TJ Enthusiast
Joined
Dec 3, 2015
Messages
216
Location
Music City USA
If you google DC relay wiring there is a lot of good information that will tell you about the different styles of relays and their applications, also tells about amp draw, circuit breakers and fuses. This will help you understand the basics.
 

C.J. Roberts

TJ Enthusiast
Joined
Jan 26, 2017
Messages
775
Location
Tucson, AZ, United States
If I'd have seen this, I would have used it when I wired my lights. Fuses and relays in one location.
1659314105524.png

https://www.amazon.com/dp/B08KHVHLL5/?tag=wranglerorg-20
If you don't need that many, or want them in different locations, these relays have a fuse already mounted in them. I used these when adding lights to my truck and my wifes Durango.
1659314165705.png

https://www.amazon.com/dp/B01NBAO1SA/?tag=wranglerorg-20
 

SSTJ

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Supporting Member
Joined
Aug 24, 2019
Messages
2,271
Location
South Carolina
I think that @Zorba will have helpful input on wiring the winch. That should be done directly to the battery, separate from any fuse blocks you install.

For everything else, there are some good threads on here about fuse block options, like the Amazon ones linked above.

Here is the thread in which I was first trying to get my mind around relays for my fog lights:

https://wranglertjforum.com/threads/rookie-fog-light-relay-question.41294/
 
OP
TjCool

TjCool

New Member
Joined
Oct 19, 2018
Messages
7
Location
Los Angeles, CA
I forgot to mention - One of the main reasons I'm doing this DIY is I had my battery tested at Autozone (since that's where I bought my last battery) and it read 12.4V. I read that a good battery is between 12.6 - 12.8 but it also said between 12.4 - 12.8 is also a good battery. Any way, I tested my battery again the next day at O'Reilly's auto parts and it also read the same and I asked the guy if that's good and he said not really and that it's probably your generator. So he tested my generator and he said it read 13.— something volts which he said is good. So I started to get a little confused how to address this potential issue. Should I buy a battery charger (and which one is a good one), and charge my battery and that will solve it. Or pursue this further and figure out how to address it.
 

mrblaine

Crew Member
Supporting Member
Joined
Nov 20, 2015
Messages
23,912
Location
Quail Valley, CA
Most winches come with the wiring that they should be used with. Use the wiring they come with or larger. Always use the same size wire or larger whenever hooking up anything electrical, the longer the run the thicker the wire. Be careful of the cheap wire brands because they will try to pass skinny wire off as thicker wire by increasing the insulation and not the wire itself. Fog lights should be wired with a relay that turns them off when you turn on your high beams. If your Jeep has factory fog light wiring it's already set up like that. If not you can wire up without doing that, but some states will fail your safety inspection because of it. Fog lights should also be below the headlights to be legal. Relay hook up is post 30 is the input. Post 87 and 87a are the output but one is at rest and the other is switched. If all you want to do is turn something on, use the switched not the at rest, if you want to turn something off wire to at rest and when switched it will go off. 85 and 86 are the coil. 1 should be hot, the other negative. I perfer to run the negative side through the firewall to a switch then the other side of the switch to ground, that way if the wire ever shorts out going through the firewall the worst case is something turns on instead of possibly burning up a wire. It doesn't matter which you use for hot or negative on 85/86 as long as you use the opposite on the other side. This is super basic info, to get you started. Google search will pull up wiring diagrams for relays. Use the search Bosh 12 volt 15 amp relay wiring.

I prefer the Hella style dual 87 outputs for stuff like headlights and foglights that are typically run in pairs. Much less wiring that way or at least cleaner wiring when you don't have to double up a pair in a single spade or butt connector if you're using a relay plug.
 

hear

TJ Addict
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Joined
Oct 18, 2020
Messages
1,330
Location
Prosper, TX
If I'd have seen this, I would have used it when I wired my lights. Fuses and relays in one location.
View attachment 347392
https://www.amazon.com/dp/B08KHVHLL5/?tag=wranglerorg-20
If you don't need that many, or want them in different locations, these relays have a fuse already mounted in them. I used these when adding lights to my truck and my wifes Durango.
View attachment 347393
https://www.amazon.com/dp/B01NBAO1SA/?tag=wranglerorg-20

I used a relay box exactly like what you posted first, and it ended up being kind of a pain, since you really have to pre-wire the whole thing, except you might not know how long your wires need to be ahead of time, etc. If I had it to do again, I think I would use the individual relays you posted second.

Edit to be clear that I'm just talking about relays in general, not for winch wiring.
 
Last edited:

Jerry Bransford

TJ Guru Moderator
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Nov 9, 2015
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24,842
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Fleming Island Florida
Don't use a relay in your main winch power connections, those must be connected directly to the battery. And there's no need for a relay if you're wiring a remote control for the winch, that circuit only draws a very small amount of current which does not require a relay, just a simple momentary action SPDT switch is fine there.
 
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Gilaguy23

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Joined
Sep 21, 2021
Messages
387
Location
A'holeville
I forgot to mention - One of the main reasons I'm doing this DIY is I had my battery tested at Autozone (since that's where I bought my last battery) and it read 12.4V. I read that a good battery is between 12.6 - 12.8 but it also said between 12.4 - 12.8 is also a good battery. Any way, I tested my battery again the next day at O'Reilly's auto parts and it also read the same and I asked the guy if that's good and he said not really and that it's probably your generator. So he tested my generator and he said it read 13.— something volts which he said is good. So I started to get a little confused how to address this potential issue. Should I buy a battery charger (and which one is a good one), and charge my battery and that will solve it. Or pursue this further and figure out how to address it.

A normal battery sitting without a parasitic draw from the likes of stereo memories, clocks will typically sit at 12.6+ - volts. Your charging system, and our jeeps use alternators, not generators, will provide a voltage reading across the battery when running of 13.8 to 14.3 volts normally. When I let my jeep sit or other vehicles for a week or more then yes, the battery voltage drops a tad to under 12.6 from those parasitic draws. If you feel so motivated go get yourself a digital volt meter from a auto parts or hardware store and you'd be amazed at what you can discover with one. A hugely useful tool no doubt. Keep this formula in mind when adding accessories. Most lights are sold listed undera "watts" rating. Like old school KC daylighters were 100 watt each. so take the 100 watt rating and divide by your 12 volt system of the jeep and you get 8.3 amps draw from each light. Consider whatyour A/C might draw, the OEM lights, big stereo and you can potentially out run the chargings systems output and kill it. Just some things to learn about as you dig into things.
 
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TjCool

TjCool

New Member
Joined
Oct 19, 2018
Messages
7
Location
Los Angeles, CA
Thanks for the insight. I had bought a Fluke 87 V last year for the purpose of using it for auto use. Well it must be that time to start using it. Just gonna go on YouTube to learn how to use it on my vehicle. I've worked in an office environment just about all my life (accounting), but not afraid to get my hands dirty. So everything I try to do on my Jeep will be a first. I've already have done a few projects on my Jeep thanks to YouTube (like installing a new radiator successfully).
 
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