Trailer brake controller and junction box

[JustinJ94FSB]

Pulling a single axle trailer 1,900lbs dry and 3,000lbs gwvr with my 1994 k1500 blazer 5.7 tbi. Wiring the brake controller. Can the 12v aux power wire that runs back to the hitch be connected to the junction block on the firewall? Also, the power wire for the brake controller itself, can i also connect that at the junction block? I dont know how much power this junction block can handle. The 12v aux wire is already pre-installed from the factory and it just happens to reach the junction block like it was designed to be attached there. I dont want to melt wires trying to overload this thing though. Any pointers?

 

[Supercharged111]

Not sure how a 94 differs, but my 97+ have 2 30A fused aux power sources. I've hooked the orange and blue wire to a single fuse on my trucks and never popped a fuse. Been towing since 2010 with the 1500 that way.

 

[JustinJ94FSB]

Not sure how a 94 differs, but my 97+ have 2 30A fused aux power sources. I've hooked the orange and blue wire to a single fuse on my trucks and never popped a fuse. Been towing since 2010 with the 1500 that way.

thats good info. thank u. So i think the difference is on the 94's we dont have a fuse box under the hood. The closest thing i have to one is a junction box on the firewall with like 5 studs with various wires/ring terminals attached to it. according to the black plastic cover thing one of the terminals is optional. but everything has stuff attached and there are less things on the cover than there are studs, so not exactly sure which is which. So in this case, i'll need to attach some sort of inline fuse, or circuit breaker which is recommended by everywhere i look. My wire which looks red, but maybe its too dirty to really tell, has an inline fuse and ring terminal already attached, and it reaches the junction block like it was intended to be there. The blue wire i have ran through my firewall and its going to be connected to the blue wire coming from my brake controller. (the blue wires are different gauge which im not sure about)(blue from brake controller is 12awg, and blue from my factory installed trailer wire has got to be 10awg) The red wire runs to the hitch. Do you mean you are running the power wire from the brake controller (mine is black) directly to the same location as your 12v red (orange) wire and both are doing fine on 30A? i dont see in any instructions mentioning any fuse on the blue wire. sounds like that one just connects on one end to brake controller, and on other end is the 7pin plug on the hitch.

 

[Supercharged111]

Yes, both the power wire to the trailer and brake controller draw off a single 30A fused without any issue. I'm not sure how robust the power supply to your stud is? It sounds like it's close to your charge/brake wire though.

 

[JustinJ94FSB]

It sounds like those fused aux slots on your fuse block are open and available for connecting things such as trailer wires and nothing else runs on them otherwise. On my junction panel I'm struggling to figure out what type of wire is supplying the power to it and if that is fused somewhere, or is it just a beefy wire running from the battery directly to it. I dont see any significant wire running to it with my brief examination. I imagine it must be pretty stout just to handle the amount of things connected to it. I am certainly no electrician. If i connect these 2 wires to the same 'always hot' terminal on this junction block, even with fuses/breakers, im trying to determine the potential for damage/fire somewhere before my breakers would trip just because of the amount of juice flowing out through that junction panel. This fear comes from a lack of knowledge so hopefully if its irrational someone can chime in and steer me straight. This might be the configuration from maybe 1988-1994 specifically and at some point, maybe 95, they added an actual fuse box with 30a aux fused slots to make it easier.

 

[JustinJ94FSB]

So this is what I am looking at. Circled in orange is my junction panel. Mainly what I am wondering is if I can connect my Red wire (battery to 7pin trailer connector, with unknown fuse size, likely 20-30a) and my black wire (12v power from battery to electronic brake controller with 20a inline fuse)

I want to connect the 2 ring terminals circled in blue, to the stud with the blue arrow pointing to it. any thoughts on this?

the only reason I am thinking so much about this, is I don't know where the power for the junction box is coming from, and if it is capable of less output than directly connecting to the battery. Or if these junction blocks are an extension of the battery connections and i should not be worried about using it.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

 

[termite]

Have you checked the FSM that is available in the engines as a sticky thread for your model's wiring diagrams or what it has to say about connecting a brake controller?
Thread '88-98 Service Manuals' https://www.gmt400.com/threads/88-98-service-manuals.43575/

If you're too concerned, extend the leads and connect them to your battery directly since it appears you have fuses in line already.

 

[name]

On My '94 Suburban witch the previous owner used to tow a 23' camper, he had wired in a brake controler and an inverter into the power block on the firewall. The controler has an inline fuse but I am not sure how big it is .

Here are some pictures that show the markings on the power block cover and if you look closely enough, some of the wires themself are tagged.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach