Electric parking brake - need wiring advice

[Littlebeefy]

1984 Bronco. Stock wiring and fuse box.

I’m terrible at electrical. I really need some advice. I need to wire in my new electric parking brake actuator. It needs two connections. The first is an “always on” power source that I can draw ten amps from. The second is a safety wire that connects to the ignition wiring. That second wire is to ensure that you cannot engage the brake while the engine is running.

There is an “ideal” way to do this and a “good enough” way to do it. The ideal way would be to take an empty spot on my fuse box. I don’t know which spot to use and I don’t know how to do that. I have a spare fuse box that I could pull a wire pigtail from. I just don’t know what I’m doing. Alternately, the good enough way is to use a fuse tap and come off an always on circuit that can supply the 10 amps. If I do that, what is the best fuse to tap?

I can theoretically do the same thing with the ignition safety wire. I could use an unused switched circuit in my fuse block, or I can fuse tap a switched fuse (that’s effectively ignition wiring right?). Same questions as above. Which spot or which fuse?

Thanks!

[Gary Lewis]

Lots of ways to do that, Chad.

First on the always-on connection, the fuse box only currently has one, and that is Fuse 1 for the speed control & stop/turn/hazard lights.  It is rated for 15 amps, but you might need the hazards while you have the e-brake on, so that might not be a good idea.  And not having looked at the fuse box lately I don't remember if there are any un-used slots that could be always hot.  Having said that, both Scott/krammtocs and I've added fuses to the fusebox so maybe we did add an always-hot circuit?  I can look later if you want.

But, under the hood near the brake booster should be a big yellow wire that is always hot.  And if you don't have the aux battery or trailer package then it isn't being used.  So add a fuse and you have your always-hot circuit.  You can see that wire at the top of the schematic below.

As for switched power, you can see in the schematic what your options are.  But #6 might be an option as you shouldn't be using the e-brake and speed control at the same time.  And, if you don't want any of those search in Big Blue's Transformation thread for what I did on adding fuses.  I think it is somewhere near this post, but I can look later if you don't find it.

[Gary Lewis]

WRONG!  That last guy didn't know what he is talking about.  The schematic he included shows that fuses 4, 8, 12, & 16 are always hot.  

This post explains how I did it.  Hope that helps, but if it isn't clear then don't hesitate to ask.

[Littlebeefy]

Thank goodness for that second guy!

But the first guy had a really smart idea. I like that yellow wire. Is the fat yellow wire with the blue connector that is not connected to anything the one you are referring to? I’m assuming it’s not the one above it that could pass for light green. If not, what is that wire?

 

[Gary Lewis]

Yes, "the fat yellow wire with the blue connector that is not connected to anything" is the one.  Put your meter on it and it should be hot.

[85lebaront2]

Yes, it attaches to a stud in an insulated block. It is used for trailer lights and on a dually the fender clearance lights.