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

Mad props to OP, by far the best DIY thread I think I've ever seen. Attention to detail is unreal.

If anyone is buying and needs to split an order, let me know. Looking into options now myself....

 

@dcsbtaco okay man everything about this is perfect haha, what can I start buying besides switches?

 

the ones used in this? Ill look at the links and also the connectors that go to the clear plug things too. ill check it out and see the cost and do a break down of what I can buy when

 

subd for a beast of a write up.

 

@Shmellmopwho lol your pic of the messy wiring as the example

 

Hahaha yep! Clean now

 

@Shmellmopwho was very gracious to let me use the photo. Thanks again! I'm glad you've cleaned things up.

 

It was my pleasure! And yes things are no longer a rats nest under the hood hahaha

 

Thank you for the walk through. Made the process very easy.

 

Thank you @tacozord for the in-depth instructions!

Finally got my large bussman mounted and installed last night. Biggest hurdle for me wasn't the wiring but rather finding a good way to mount the bussman in my engine bay. I mounted it in the same location you identified but since I have a s/c, most of the pre-made mount options would not fit. Ended up getting some angle iron and that worked well. I'll update later when I can take some pictures.

 

Wow. What an excellent DIY guide. I wish they were all this detailed! Although this has taken me nearly 3 days to read and re-read in it's entirety, I think I am going to at least price out this exact same set-up to determine if it's within my budget as I am now confident enough to tackle this job.

I have a question though and this is coming from someone who has nearly as little knowledge about electrical systems as possible: Following the guide, there are five accessories that are using relays, and five that are fused-only accessories. The five relayed accessories should be accessories that use a higher amount of power, such as larger light bars etc. Therefore, these are the accessories that were chosen to be on switches. However, there was no wiring done to make it so the fused-only accessories are able to be connected to switches? Forgive my lack of knowledge, but I am just trying to understand why we would want all ten accessories to be connected to a physical switch, or at least have the option.

My scenario is this: I want to build this for two accessory lights at this time, as well as plan for future accessories. Right now, they are a simple LED bedlight kit and LED Halos (XSB 2.0 from The Retrofit Source). Both of these are very low power (unsure if that is the correct term), and it would seem to me that I would want these on the fused-only accessories to save the relays for accessories that require more power. But, I want both of these to be switched inside the cab (using the IggyCorp switch panel and OTRATTW Contura V switches). I plan on re-reading the tutorial another couple of times to make sure I really know what I am doing and not just following step by step directions....but this problem has me confused.

As a side note, I only have two of the physical switches and they are both ONLY dependent upper LEDs, meaning I likely won't be tapping into the dimming circuit or having those addition wire harnesses. Is there a downside to including these in the main harness that will go though the firewall and just leaving them unconnected, in the off-chance that I will decide to swap the switches all out for ones that have independent lights?

 

Sub'd!

 

I'll take a stab at the answers but note I'm not an electrician nor am I well versed enough to be an expert but this is what I've found in my own research.

With the way the system @tacozord described, the bussman is always powered on since power is always being fed to it UNLESS you flip the breaker. If you connected a switch to the fused only leads, the switch can be used to power your devices regardless of if the truck is on or not. It will always be powered. For me, I like using the relay so that I can't accidentally leave any of my accessories on without the keys in the truck in the on-position.

You could easily wire a switch to power devices which are fused only (no relay). You would just need to run a switch inline with either the power or ground cable. Personally, I'd put the switch in line with the ground so I'd avoid having the hot 12v come into the cab and the switch would still work as expected.

In terms of the extra wiring, I don't think it would hurt to have the extra wires running in the harness. I'd just put some electrical tape over the ends so they can't accidentally connect to anything,

hope that helps.

 

Yes this is very helpful, as I do want those fused-only accessories to be able to be turned on and off when desired, and whether the truck is on or not doesn't matter to me in this case.

Doesn't that mean whatever accessories connected to the fuse-only slots will always be powered and on if not connected to a switch? (Assuming that the accessory is turned on if power is going to it, such as an led strip light, and doesn't have some sort of external switch such as a remote or something). I guess I am just trying to determine the function of wiring for those five fused-only accessories.

 

Yup, thats correct. Anything connected to the fused slots will always be powered on. Theres plenty of cases where you might want to consider using them.

For me:
1) hood LED strip
2) CB / HAM radio
3) usb/12v outlet in the truck bed
4) bed lights

All of the items above I'll be putting a switch on them (2 switches for the hood LED strip and bed lights probably: 1 regular on-off switch and a pin switch so that if i close the hood, even if i left the switch on, it will turn off the lights). Just really depends on what you plan to install. At the very least, it opens possibilities for you in the future.

 

Great thread. Just stumbled on this product line and then found your tutorial.

 

Pics of the installed product (still need to finish adding a few more wires to the box, running some additional wires in the cab, trim the power cables in the engine bay, not to mention bolting the box to my home made mount ... its zip tied right now, haha)

 

So how much did this whole system cost you to build? I'm curious if it would still be cheaper to build one for someone like me who doesn't have all the crimpers/pin tools/etc than just buying one premade?

 

@mountainmonkey
There's a group buy going on right now. I think it is about $120 with all the relays and wiring. It is definitely more expensive to do yourself because of the minimum order quantities from the distributor. I think you have to buy like 4 or 5 complete kits to make it pay off.

 

So I added another switch to my fuse box and after installing it, none of my factory or add on switches illuminated when the headlights are turned on. Also, the factory entune unit stopped dimming as well. After a little bit of googling, I found the problem was a blown fuse (which I suspected but wasn't sure where to find it). It ended up being the 10A "TAIL" fuse in the fuse panel under the dash. Once I replaced it after making sure all my wiring was correct, the switches illuminated again.