DIY - Build and install a Bussmann RTMR Fuse/Relay Block

My Viair draws 30 amps, so it could go through a bussman.

I don't know how much current a dual ARB compressor draws - would not be surprised if it pulls more than 30 Amps.

 

https://www.arb.com.au/assets/air-lockers/6-07.pdf

The twin can pull 50-69A under load. The single maxes out at 32A.

 

The original series of post are very in depth and cover a lot of background on proper crimping, it IS a lot to digest if not familiar with the process. but it is broken down very well, take as much time as needed to read and reread. don't be in a rush to jump in...

To this day I use his information as a reference guide from time to time, It took me almost year of reading and rereading, buying tools little by little by little, until I built the bussman set up which To this day I have not installed. changed from an offroad to an sr5 and the mounting tray In bought no longer works. but I do not regret for a moment building my own.

 

First - it's not really all that complicated.
Second - it's just a simple RTMR waterproof Fuse Relay box. Thats all.
Third - most of it is highly detailed, but Ive built about 20 of them for my friends now. I can bang one of these puppies out pretty fast now. But - its a pretty good starter for people who might want to build a Bussman RTMR.
Lastly - don't kill yourself - Toyota still needs more of your money...

 

Yes, its quite well documented - especially with the crimping and soldering.

 

so im looking to do an RTMR to condense stuff in my tundra.. i have ground switched headlights and run a beefier harness for the 100w halogens in it. plan on putting the headlight stuff all in the RTMR too. Providing 12v to the relay bus should allow me to use the ground switch for controlling the relays yes? then i'd just be all ground switched for my accessories too then which, no big deal.


im thinking it out without making a diagram right now. which is making me wonder if its even doable.. so yes.. im probably asking an obvious easy question. kind of a spur of the moment thing..

 

ok so it seems the fuse bussed with a non bussed relay side RTMR would be ideal for my needs. but it seems 15305-5-2-4 is not available anywhere currently.. anyone know of a place with them instock?

 

https://m.delcity.net/store/ISO-280-Combo-Panel-!-Partially-Bussed/p_804298.h_804299
It’s the 303-5-2-4, just means the mounting holes are standard rather than metric. Probably why you can’t find the 305.

 

Hmm. That should work. Hopefully they have it in stock just says call. I’ll order it when I get home. That number on mouser says “obsolete”

 

I tried loading it into a cart and it added so I thought it might be available. If you’re just activating the relays by switching the coils to ground you can use the fully bussed version. In that instance you build it with the relays right side up as described by Tacozord.

 

Yea the tRicky part is when I try to control the Cadillac horns from this thing too.. that would need to be power switched. Short of me grabbing the trigger from the spiral cable switch. I placed the order. We’ll see if it shows up. My wires behind schedule anyway.

 

You can use a ground switched relay to trigger a power switched relay and vice versa.

 

I know. Just trying to keep the clutter down. It’s easy enough for me to pin some extra pins. I’ll just make a small harness to power the coils of the relays off the buss stud for the fuse

for the headlights I’m just going to give the relay ground and power from the headlight socket itself. Like it is with the current setup.


Hindsight is now telling me I should have just ground switched the horns by just modifying the trigger point I use. Lol

 

I was able to buy 15305-2-2-4 at Del city a few weeks ago, granted I haven't gotten a shipping notification yet.

I think that's the newest edition as a search for the number in this thread turned up a lot of deprecated/replaced by/out of stock results.

 

I ended up with a few extra fuses and relays anyway since my compressor draws more than the 30A per circuit max. Even so the rtmr’s are so compact the tray plus extras takes minimal space.

 

eh everything is ordered. we'll see how i make use of this mess. either it'll come out pretty good looking like my radio harness i did (that was fun sourcing all the toyota micro pins without pigtails) or im going to regret not just doing the dual bussed. LOL
for a little bit it'll just be the headlights and horns while i devise how i want to mount my lights. can never go back to non 80/100 halogens though.. its life changing seeing that well at night.

 

There’s ways to make any panel work so it’s not as if you’re sol with one or the other. I look forward to seeing it.

 

MY recommendation is: Know what you are going to connect to, diagram it all out. Find out what amps each item draws, this determines the wire gauge to use - then buy the RTMR supplies, then build it out - including the harness to/from the RTMR, then each accessory cable - test them out BEFORE you install it into the car - then - LABEL EVERYTHING TO DEATH. THEN pull it all apart and put it into the car. THIS saved me so much time and trouble - especially when I switched wires accidentally (it happens) and other stuff like loose connectors, bad solder joint, etc.

Then its cake walk after that.

 

OK. I'm late to the game here but....

I bought a Bussmann 15303-5 from a TW'er. (I forget who). It came assembled with a main switch/circuit breaker and color-coded wiring for each relay; a heavier gauge wire and a lighter gauge wire. I'm trying to connect it.

It was my impression that I should connect one pole of a switch to the lighter wire, and the other pole of the switch to ground.

Then I would connect the heavier wire to the Plus (+) side of the device and the Negative (-) side of the device to ground.

OK. I did that. And it's not working. What am I doing wrong?

 

According to the OP the 15303-5 has one buss for the fuses so there should be a jumper over to the relay side (one for each fuse & relay) that supplies device power. If your switches connect each coil to ground then the other side of each coil will need power. There are a varieties ways to do this. One would be to daisy chain the coils to one of the 10 fuse slots. A different arrangement would be to daisy chain the coils to ground and supply power to your switches from an add-a-fuse inside the cab. Without more info I can only guess.