Convenient spots for relays and grounds in engine compartment

[Jhuff]

So I've been working on some power modifications for my RSE stepslides, to make them more integrated with the vehicle and give more control to deployment.

My first experiement failed, but I did find a few handy spots for relays and/or grounds that might assist other projects:

While I prefer building a plate to keep all my aux-wiring organized and in one spot, these single points were very helpful for quick experiments.

Inside the engine compartment, along the seam between the cowl and the firewall, there are body grounds screwed into welded nuts on each side of the compartment. There are also several unused weld nuts that would be ideal for grounds and/or relays.

Unfortunately, the unused weld-nuts are not yet tapped. I thought my project was over until I bought the correct taps, but realized the the bolt used for the existing ground is very hard and tapered. I believe this screw is designed to self tap into the softer weld-nuts.

The existing bolt worked fine when used to tap the two unused weld-nuts beside it (as pictured above), but I can't guarantee this is what it was designed for. A tap would be safer if you have any hesitation, or don't have a replacement metric bolt on hand to replace this one, if broken or stuck.

This was my end result:

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[Broncovt]

Hello,

Stumbled across this as I too would like to use one of those bolt holes for a ground. The main ground appears (??) to be an M6 but the appropriate nut seems rather loose. What size tap did you buy/use for these unused locations?

 

[Jhuff]

I didn't have to buy anything for this particular project.​

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The "nuts" on those unused holes (at least on my 2022 bronco) seemed to be a soft metal or other material. I assumed they were designed to be tapped by the OEM bolt, and thus I tapped them by borrowing the neighboring ground screw.​

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The picture shows me using an 8mm socket, so I'm thinking mine were M5 bolts. Maybe your bronco is a little different, or you are working on a different hole?​

 

[Broncovt]

My Bronco is a 2023. Using the exact hole you show working on. A verified M5 bolt drops straight through and it does appear to be non-threaded. The bolt you used to, from the existing ground, thread this hole is different than mine. No taper on mine at all. Odd, yes? Guess I’ll try an M6 tap and see how it goes. I hate to stack ground stuff.

 

[Jhuff]

My Bronco is a 2023. Using the exact hole you show working on. A verified M5 bolt drops straight through and it does appear to be non-threaded. The bolt you used to, from the existing ground, thread this hole is different than mine. No taper on mine at all. Odd, yes? Guess I’ll try an M6 tap and see how it goes. I hate to stack ground stuff.

Darn. Looks like I may have to edit the OP, which is unfortunate. This little discovery on my 2022 saved a lot of time.

I guess we will have to wait and see which of our situations is more common?

 

[mntlimg]

What did you use as the power supply for the switch for the relay? I have a set of driving lights I am installing in my 2023 base bronco delivery May 2023 and I like the relay mounting location. I will check my mounting nuts.

 

[da_jokker]

For me, I just mounted some stuff on the inner fender side wall in your picture, using whatever sheet metal screws I wanted. It's a nice spot especially since that is where all the Aux Switch wires are.

Maybe some aftermarket vendor can come up with a generic mounting plate that uses your weld nuts, but makes that while inner fender section available for mounting things...then they can charge $200 for a peice of metal.

 

[BroncoFrog]

Here is where I put my relay for my backlights.

 

[Jhuff]

What did you use as the power supply for the switch for the relay? I have a set of driving lights I am installing in my 2023 base bronco delivery May 2023 and I like the relay mounting location. I will check my mounting nuts.

Edited: I was trying to use an aux switche to keep the relay normally closed (on) all the time while the aux switch was in it's normal position of being "off". Hoping I could turn the steps off by turning the aux switch on.

If I recall correctly, I used the positive side of that button's wiring (direct from the battery) as the intended switch loop, but also tapped into that constant power for the relay power, which goes to ground after leaving the relay.

The setup failed my intentions... Those aux switches power off completely when the bronco turns off, and don't turn on instantly when the bronco starts up. The result was some really wonky behavior by the steps on startup as they tried to "relearn" their position, usually while the door was still open.

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