This will be my first time wiring lights but I think I understand the idea behind relays. Steal an amp from one of the other circuits already inside the truck without putting a strain on the circuit you are drawing from. Since these relays don't draw much can I use one tap for multiple switches? For example can I run one tap to a distribution block and run 4 out without stressing the system? I know how to figure the size of fuse needed but how do I figure the necessary gauge wire, will 14 gauge cover all my needs other than the line from the battery to the distribution block.

 

Depends on what you are wiring in. I just did a boat for a buddy last weekend and wired in a switch panel and ran eight different devices off of it. I ran 8 gauge to the common at the panel and for some things I was able to run as thin as 22 gauge while some things I installed like the bilge pump got 12 gauge wire.


This will pretty much tell you what gauge wire to run based off amp draw or wattage:

https://dodgeforum.com/forum/3rd-gen...nd-relays.html

 

Thanks Hammer that helps. I find a lot of Bosch style relays but none actually are the Bosch brand is this the type of thing you want to buy name brand.

 

Nah, that's just the common name for them. I don't think I've held an actual Bosch one in my hand in probably ten years. Should run you about $5 at the auto parts stores...

 

I dont really get what you are trying to do... There's no point in "tapping" any fuse/circuit to install a relay and then fuse that relay. Makes no sense unless your tapping an ignition controlled wire for key-on/lights on kind of thing?
'06+ are a new ballgame for wire tapping because Dodge uses Multiplexed wires that are all can bussed.
Find the wire you want to trigger the relays on, whether it be the lowbeam wire/highbeam wire...etc. If you want to manually switch it yourself, you don't want to tap into any existing wire in the truck! If you decide to tap into a wire for ease of On/OFF with the key, you'll want to install a diode to isolate the circuit your adding to prevent any kind of voltage spikes that could feed back into the stock wiring. That will go betwen your relay signal tab and the grounded tab. Usually across pins 85 and 86. The diode must face the proper way, gray band towards ground side. This directs voltage spikes to ground rather than into your stock wiring. 1n4005 at Radioshack will be sufficient up to 30A.
Now, the powered wire(fused) should go directly to the battery. Ground from the relay should go directly to frame ground, NOT a grounded wire you find inside the truck as those are can bus controlled too.
I'd really stay away from tapping any wires unless it's the cigar wires that are used to run accessories off of. Otherwise, your tipm and cluster won't like it very much when you over draw current. Relays draw current on their signaled wires. Generally about 250mV. Doesn't seem like much but it could be problematic in time.

You can use 1-relay to support as many devices as you want that are within the relay's current capaibilities. Most are 30A or 40A. If your unsure, PM me details about what the wattage is and how many and I can guide you better.

 

TIPM can be a bit of a PIA, but it really just means you gotta do a little more testing with a meter before just going in and tapping a wire or relay.

What exactly are you attempting to do?

 

If what I'm saying doesnt make sense it's because i don't really know what I'm doing I'm still figuring it out. I have two sets of Hella 500ffs for the front and also some led spot lights for my trailer, I pull it most days during the week and have to back it in my long drive at night. I don't use the cig lighter so can I get power from it into a switch then to the relay with 14ga stranded and the other side of the relay will get power straight from the battery with an in line fuse and 12ga wire then from the relay to the lights with the 12ga wire. If this works can I use the lighter to power all 3 switches to 3 seperate relays? Don't get to complicated I am new to this, you lost me before dog.

 

ok. The whole reason to use a Relay is for the relay to carry the current load. Current is rated in Amps. You can have a 12v-1A circuit or 12v-40A circuit. It all depends on your light source needs. Relay's need to draw ~250mA of current to activate it's internal solonoid. Upon activation, it transfers power from the battery to your headlights. Using the cigar wire(pink/yw) is only to supply the 250mA to the Relay for it to work when you turn the key to acc/run/start position. I imagine you would not want constant activation of the relay/lights because of this. What you can do is install a toggle switch between the cigar wire and the relay. OR, to completely eliminate tapping the electrical system, you can do this which is the same thing and even allows you to turn the lights on without the key in the ignition;
Bring ONE 12ga wire from the batery into the cabin and attach it to pin 30 on your relay. This 12ga wire will be fused near the battery. You'll thentake a smaller 14 or even 16ga wire and T-tap the power wire, run the thinner wire to one side of your toggle switch and then the other side of the toggle switch will go to pin 86 on the relay. Ground pin 85. Pin 87 will go to your Hella's. This method draws power ONLY from the battery and will not effect anything OEM electrical! It allows the relay to carry the current. If you basically dropped a switch in the middle of the headlight power wire to turn on/off power, the switch would be handling all the current. While this can be done, and since you use your light all the time, I would not reccomend doing this and you would need to get a beefy toggle switch rated above 20A.

My signature has DIY Hella install with pics and fuse/wire specs. Since I rarely use my lights I went the direct switch route and bypassed the relay idea. Again, a relay is the safest way to go!

Now for your rear LED's, I installed back-up lights myself and used two relays to toggle the back-up lights automatically. I believe the wiring chematic is in MY Light Pics link. I think it's a link where my back-up pics are? I basically set it up so they only turn on....When I have my headlights on and when I put the truck in reverse. No need for the without headlights on as it would be daytime and you can already see.

 

I'm not a fan of running high amperage into the cab. Many a cab fire has been started by doing so. I use relays to keep all the high voltage (comparatively speaking - of course) in the engine bay where it's supposed to be and just running 1/3 of an amp (which is what I always thought it took to "trip" a relay, 'dog says even less at 1/4 A or 250 mA).

Take you a good gander at the pic in that DIY of mine I gave you the link to...

 

How close does the fuse have to be to the battery, everyone says put it close but is 36" just as good as 6". I was looking around the engine bay and the area around the battery is packed full of stuff for my snowplow, but there is plenty of space by the passenger side wheel well since the factory air box has been removed.