DIY switch and relay install

There isn’t a lot of information regarding DIY installs of switches and relays, usually it is the pre built ones so I thought I would share my experience and hopefully help anyone else who attempts to do this.




The first step was to choose a location, I decided on the holder for sunglasses. Cut it out with a Dremel and it was a snug fit, but I got it work fit eventually.



The relays I chose were already pre wired and in a bundle, making everything a lot easier. I mounted them about two inches above the normal location everyone puts them in.





If anyone needed clarification on wiring a relay, here is a basic diagram for the ones I received. Almost any automotive relay will be like this or very similar. I used all wires except for the blue one. The blue wire is a NC (normally closed) contact. So if you are having issues with your switch being reversed, swap your blue wire for your green wire.




Mounting the switches where I put them wasn’t as challenging as I assumed it would be, the only issue that I have ran into was the plastic board with the dome light and switches being loose in general because when I cut out the plastic so the switch board could fit, it removed the screw hole that allows you to tighten it to the roof. I’m planning on finding a remedy to this but I’m kind of burnt out from wiring for the last couple hours. I used a add-a-fuse from the 7.5A ACC that is under the drivers fuse panel, I didn’t care about the switches engaging with the dimmer switch, just wanted them to turn on when the key was engaged, and off when I turned the truck off.




I wired up all switches, even though currently I am only using one. This will help me save time later when I want to add more lights or anything else. To save myself from confusion I used my meter to do a continuity test on all the wires, then marked them with electrical tape on the relay and also on the switch side.

another important thing to pay attention to is your amperage draw from your lights. I am using HELLA Rocklume 280’s, they draw a substantial amount of power. Running both of them as ditch lights pulls almost 30A, make sure your relay is rated for it and your fuse that you’re using as well.

any questions or criticism is welcome

 

Nice right up, thanks. Do you put the fuse between the battery ( or wherever you draw the power) and the relay, or between the relay and the light you are powering?
Thanks in advance.

 

It really depends on your setup. If you aren't using a relay (you would only do this if whatever you are powering doesn't draw a lot of current, things such as interior LED's or something small) then you would put your fuse before the switch. If using a relay like I did, then you would put your inline fuse before the black wire (#30 on the diagram).

On my setup I have 3 safety nets. The fuse on the Add-a-fuse, the fuse on the switches, and the fuse before the relay. This is really overkill but I would rather have that then burning up my switches or anything else. Also when doing this make sure you have the correct fuse for your amperage draw and also the correct order. For example, I would want the fuse on my add-a-fuse to be lower amperage then the fuse on my switch because it is before it. If i had it vise-versa, it would blow the larger fuse, then the smaller fuse, then most likely burn up the switch. In my situation the lights I am using draw a good amount of current (30A), so I went did a lot of safety measures.

 

Thanks for the info. I must of been tired when I looked last night. I see on the diagram this morning the black wire says fused right on the diagram
Thanks again

 

Nice write up.

If folks want a deeper dive, this is like taking a three credit college course on the subject:

https://www.tacomaworld.com/threads/diy-build-and-install-a-bussmann-rtmr-fuse-relay-block.399454/

 

I saw that write up as well, I just didn't want to spend the time and money on it so I went the mediocre route, ill post more pics when my ditch mounts arrive.

 

Always always always fuse what's feeding the relay/ load AND the feed to the switches. Keep the fuses as close as practical to the battery as well. Fuses are there to protect the wires themselves moreso than whatever it feeds. The relays themselves draw very little to energize. An add a fuse behind the cubby will work perfect

87a is live when the relay is off. Cap that wire or remove it and put an empty crimp connector on the terminal to avoid shorting it out by mistake. I typically wire the fused feed to 87 if I don't need 87a

@skedrc damn you've been busy. Nice job.
I hope everything is wired to the relays to the point of just plugging in whatever you're going to switch.

As for fuses, each relay should have it's own fuse, sized for the load, not the relay. The relays are typically rated 30 amps. You don't want all the toys turning off when one goes bad...

If I'm reading this correctly; each switch has it's own fuse, fed from the add a fuse as well. If that's the case, then those fuses should be sized for the coil load. The add a fuse, sized for all of the relay coils load.

Let's see front.... The finished product.

Ya, I know that's for broken links. You get the idea..
lol