I've mentioned before that I've been working on an auxiliary relay center for my car off and on the past few years, and have kicked it in higher gear this year. I posted on my main images thread, but over here it should be more visible to those who might be interested.
Why would someone want to add an additional relay center? This practice is somewhat common in the offroad community, where 4x4s get additional accessory lights, winches, air compressors, etc and require a clean and tidy way of adding these accessories with a control switch in the cabin. Otherwise you wind up with a rats nest of power and ground wires, fuses, relays, cluttering up the engine bay and passing dozens of wires inside the vehicle for a bunch of random switches.
On my car I have added a number of circuits, including one outside the car, and wanted to get ahead of it before I got that same rats nest condition going on.
In 2019 I did some searching for small solutions to add as many as 5 circuits, and came across an extremely detailed how-to on Tacoma World. This how-to was of course tailored to current model Tacomas with the aforementioned goal of adding circuits for lights and winches, but the principle is the same so long as the busbars, relays, fuses, and wires used are suitable for the circuits intended. Given I will only be using RGBW LED bluetooth controllers, my needs are small.
From that Tacoma World how-to I settled on the Bussmann RTMR 5-relay setup. It's capable of having 5 fused relay circuits, as well as 5 fused non-relay circuits (total 10). I will only be using relays as I want the circuits to be powered from the battery and switched on only when I push a button inside the car, so I have spare fuses in the empty slots.
The switch bank was custom built in 2019, and I followed Keith's lead by adding them below the steering wheel. The result is a very clean installation that would normally not be noticed by the average person. They are blue LED lit switches, get indicator light power from the car's interior light circuit (lit only when the cars lights are on), and they only get power from the accessory circuit to pass to the relays. They only pass power when the ignition is on, eliminating any possibility of leaving something on and walking out to a dead battery.
They're wired to a molex connecter behind the knee bolster, so the bolster can be easily removed if needed (came in handy when I had to do the evap a few months later). Then a separate harness passes through the firewall, containing only one wire per circuit, up to the relay center. Power for the circuits does not pass through the switches, they only supply a small 3-5A signal when pushed to the relevant relay. The relay passes power from the battery and fuse to the circuit, hence only small wires are needed and the bundle thickness passing through the firewall is minimal.
Next, the Tacoma thread went into spectacular detail on building the RMTR, pinning it and making jumper wires, using the right pins and the right weatherpack seals. I finally got around to building it last year once we settled into our house and I had built a custom workbench in the basement for my tinkering.
I neglected to grab a picture of the unit itself, will add one later.
Now, I could simply fab up a mounting bracket and install it in the car at this point. But, I don't like things that look like they don't belong. The only space I have available is the space between the passenger strut tower and my cone air filter, which is also somewhat protected from direct engine heat. I took measurements of the area and then hit the yard, opening the hoods of a dozen different models before coming across a recent Stratus R/T sedan. I believe it was a 4-cyl, not sure, but the relay center service the entire car was the perfect size. I snipped all the wires and removed the relays and fuses (yard charges extra for loaded relay boxes) and took it home.
First order of business was to take it apart (3 sections, the base, the midsection containing the busbars relays and fuses, and the cover) and get out my multi-tool to gut it.
Here it is separated and gutted, busbars and relay socket section cut out:
Then I traced out the bussmann, ground busbar, and the Stratus relay box on a sheet of plastic that I had used in 2018 to make a new heatshield, and cut out a new platform for the bussman and ground busbar to attach to.
Here is the new plate, bussmann unit, sitting inside the Stratus box(nothing attached yet):
Cover installed. In addition to the KnuKonceptz fuse holder for my audio system being attached at the front below the air filter, this is really all anyone will see. I have since cut out the harness guide since it was interfering with the strut tower, and removed the mounting structure near the battery + input (the stratus' jump point) to make it fit better. The plan is for the battery input to enter at the Stratus' jump point, and for the switch harness, accessory circuit wires, and ground pass through the original Stratus harness point, where it will all be kept neat beneath the fender.
Mockup fitment in the car, you can see on the left where I am using the factory fender attachment point for the original air cleaner resonator assembly. That bit is plastic-welded to the base of the relay box. Next I need to work on a second attachment point, and add some foam to restrict vibrations against the strut tower:
Once all attachments are finalized, I will clean up the individual pieces, and paint the bottom and midsection flat black. The cover I am undecided on. My factory relay center cover is currently sanded smooth and painted body color with my Luna logo, with 2K clear. Leaving this one factory might be misleading with the note about the jump point (I'd rather continue using the factory LH jump point) and it wouldn't match the original relay cover and the plenum. I may belt-sand the lettering away, paint DSB and clear it, and add a Special badge to it. I would likely plastidip the red jump point cover. We'll see.
Then I would only need to finish pinning the switch harness, install the base on the car, make all my connections, and snap it together. Plan is to have this done for Carlisle. Maybe even have it ready to mount to the car for the CEMA show on 6/10 (not necessarily functional yet).
Why would someone want to add an additional relay center? This practice is somewhat common in the offroad community, where 4x4s get additional accessory lights, winches, air compressors, etc and require a clean and tidy way of adding these accessories with a control switch in the cabin. Otherwise you wind up with a rats nest of power and ground wires, fuses, relays, cluttering up the engine bay and passing dozens of wires inside the vehicle for a bunch of random switches.
On my car I have added a number of circuits, including one outside the car, and wanted to get ahead of it before I got that same rats nest condition going on.
In 2019 I did some searching for small solutions to add as many as 5 circuits, and came across an extremely detailed how-to on Tacoma World. This how-to was of course tailored to current model Tacomas with the aforementioned goal of adding circuits for lights and winches, but the principle is the same so long as the busbars, relays, fuses, and wires used are suitable for the circuits intended. Given I will only be using RGBW LED bluetooth controllers, my needs are small.
From that Tacoma World how-to I settled on the Bussmann RTMR 5-relay setup. It's capable of having 5 fused relay circuits, as well as 5 fused non-relay circuits (total 10). I will only be using relays as I want the circuits to be powered from the battery and switched on only when I push a button inside the car, so I have spare fuses in the empty slots.
The switch bank was custom built in 2019, and I followed Keith's lead by adding them below the steering wheel. The result is a very clean installation that would normally not be noticed by the average person. They are blue LED lit switches, get indicator light power from the car's interior light circuit (lit only when the cars lights are on), and they only get power from the accessory circuit to pass to the relays. They only pass power when the ignition is on, eliminating any possibility of leaving something on and walking out to a dead battery.
They're wired to a molex connecter behind the knee bolster, so the bolster can be easily removed if needed (came in handy when I had to do the evap a few months later). Then a separate harness passes through the firewall, containing only one wire per circuit, up to the relay center. Power for the circuits does not pass through the switches, they only supply a small 3-5A signal when pushed to the relevant relay. The relay passes power from the battery and fuse to the circuit, hence only small wires are needed and the bundle thickness passing through the firewall is minimal.
Next, the Tacoma thread went into spectacular detail on building the RMTR, pinning it and making jumper wires, using the right pins and the right weatherpack seals. I finally got around to building it last year once we settled into our house and I had built a custom workbench in the basement for my tinkering.
I neglected to grab a picture of the unit itself, will add one later.
Now, I could simply fab up a mounting bracket and install it in the car at this point. But, I don't like things that look like they don't belong. The only space I have available is the space between the passenger strut tower and my cone air filter, which is also somewhat protected from direct engine heat. I took measurements of the area and then hit the yard, opening the hoods of a dozen different models before coming across a recent Stratus R/T sedan. I believe it was a 4-cyl, not sure, but the relay center service the entire car was the perfect size. I snipped all the wires and removed the relays and fuses (yard charges extra for loaded relay boxes) and took it home.
First order of business was to take it apart (3 sections, the base, the midsection containing the busbars relays and fuses, and the cover) and get out my multi-tool to gut it.
Here it is separated and gutted, busbars and relay socket section cut out:
Then I traced out the bussmann, ground busbar, and the Stratus relay box on a sheet of plastic that I had used in 2018 to make a new heatshield, and cut out a new platform for the bussman and ground busbar to attach to.
Here is the new plate, bussmann unit, sitting inside the Stratus box(nothing attached yet):
Cover installed. In addition to the KnuKonceptz fuse holder for my audio system being attached at the front below the air filter, this is really all anyone will see. I have since cut out the harness guide since it was interfering with the strut tower, and removed the mounting structure near the battery + input (the stratus' jump point) to make it fit better. The plan is for the battery input to enter at the Stratus' jump point, and for the switch harness, accessory circuit wires, and ground pass through the original Stratus harness point, where it will all be kept neat beneath the fender.
Mockup fitment in the car, you can see on the left where I am using the factory fender attachment point for the original air cleaner resonator assembly. That bit is plastic-welded to the base of the relay box. Next I need to work on a second attachment point, and add some foam to restrict vibrations against the strut tower:
Once all attachments are finalized, I will clean up the individual pieces, and paint the bottom and midsection flat black. The cover I am undecided on. My factory relay center cover is currently sanded smooth and painted body color with my Luna logo, with 2K clear. Leaving this one factory might be misleading with the note about the jump point (I'd rather continue using the factory LH jump point) and it wouldn't match the original relay cover and the plenum. I may belt-sand the lettering away, paint DSB and clear it, and add a Special badge to it. I would likely plastidip the red jump point cover. We'll see.
Then I would only need to finish pinning the switch harness, install the base on the car, make all my connections, and snap it together. Plan is to have this done for Carlisle. Maybe even have it ready to mount to the car for the CEMA show on 6/10 (not necessarily functional yet).
LUNA
2002 Chrysler 300M Special - Deep Sapphire Blue/Storm Gray Metallic - 142,000 miles
The fleet
2016 Jeep Wrangler Unlimited Sahara | 2020 Dodge Durango R/T AWD | 1929 Ford Model A Tudor
