Hey guys,
I'm working on wiring a trailer braking controller in the Jim Jim. I've read on other posts that the wiring is already present beneath the air box next to the fuse box. I can't find the $@&© things. From what I understand, they're blue and red, red for power, blue for braking signal. I took some pictures of the wiring in the area they're supposed to be located. These pictures are attached. A few other things I've got going on with it are I'm thinking of replacing the shocks soon, any recommendations are welcome. I'm thinking of going with the special spring assist shocks in the rear for when I pull the pop-up, but that'll probably only happen a few times a year, so maybe it's not worth it?
The other thing is I'm sick of my ABS and airbag light being on. ABS shows front (can't remember what side) wheel speed sensor is bad/erratic signal. I pulled and replaced, no change. The airbag I have no code for. I MIGHT buy a reader for it depending on cost for the local shop to read it.
OOOH! AND I'M 203,000 miles old now!
~DC

 

I just did this very same thing on my 2000 Jimmy (2dr-2wd). It seems that the wires you are looking for are only there if you have the Heavy Duty trailer wiring package(or whatever it is called). Mine had the basic towing option. The one used for non-electric brake trailers. Those wires are found behind the rear bumper.

I had to run my own brake controller wiring. If you need help in how I ran those, let me know.

 

Hey rxJimmy, I know what you are speaking of regarding the wires behind the rear bumper. I have already located those. There were more wires present there than the basic four, there was also a blue one. So I suppose I could trace it back up, but that would be a pain and a mess. Did you locate yours under the airbox?
~DC

 

I think there were 6 wires back there. I think one was for reverse lights, Maybe the other for a dedicated brake light (not integrated with the turn signal). I didn't use them. All of those wires at the rear were fairly thin wires. not heavy enough for brakes. There were no heavy 14 or 16AWG wires were in the engine compartment on my Jimmy. Had to provide my own along with the recommended auto-reset circuit breaker. I also had to drill holes in the firewall and alongside the seat in the floor for the wires to the rear. I ran 2 wires, one for the brakes and the other for auxiliary 12V power to the trailer. The rest of the wires necessary for the brake controller were tapped into other wires within the cabin.

 

rxjimmy you are correct. the stock non heavy duty trailer wires are a six wire configuration for basic trailer wiring. The heavy duty package was an 8 wire configuration with heavier gauge wires for brakes and aux. power. I found an add on two wire system on a salvage yard blazer when looking for other parts. What luck ! P.S. there is a trailer wire section in the owners manual that identifies the wire colors and function.

 

Terrific, writing this all again because my government laptop signed me off :-P

Good input, 2004 Blazer. What I have done thus far is switched from a 4-pin to a 7-pin. I cut off the 4 and wired all those into my 7. The wires present near the bumper were: yellow, brown, white, light green, dark green, and blue. I wired all of those into their respective places on the 7-pin. The only one that didn't have a "home" was the light green, which is still disconnected. The blue wire from the blazer was wired into the blue "e-brake" wire on the 7-pin connector. I figured that was the blazer's e-brake wire. What else would it be? Anyway, the problem in a nutshell is that I can't find where that blue wire "comes out." Here is where I got the idea that it makes its appearance right under the airbox.
2000 Chevy Trail Blazer Braker Controller Install
Regarding auxillary power, my trailer does not have a battery, so I do not see a need to wire a power wire to the back of the blazer. I don't THINK that the trailer brakes would require the auxillary power. Am I wrong?

Anyway, I think that's everything I had written before I got logged off. :-p

 

Any advice for running the brake controller wiring would be more than appreciated. Looks like I have to do power, ground, wire back to the harness, and wire from the brake wiring to the controller?

 

I mounted the circuit breaker on the bracket for the ABS. One wire comes from the 6mm terminal in the corner of the fuse block and out to the CB. From there, I ran 2 wires (trailer brake wires, Trailer Electric Brake Wire High Temp 14 2 15 Amp 10' | eBay) thru the firewall. Wiring is sleeved under the hood and gets routed behind the ABS.From there, it goes thru the firewall between the Power Brake assembly and the main power connector. Don't forget the rubber grommet. The available space is minimal. I was able to drill this without removing any other items from under the dash. Once under the dash,I routed one of the wires to the brake controller. The other just continues on to the rear of the car. The output of the brake controller (and the aux power wire) get routed behind the driver's kick panel and under the carpet. There is a rise in the floor, along side the seat, where the surface is more vertical. I drilled and grommeted for the wire to pass thru to the underside of the vehicle. Form there, it is a fairly simple issue to rout the wire to the back of the vehicle.


My use of the aux power wire is just in case. I may add an external battery, or I may add some loading lights on the trailer. It uses the same fuse and circuit breaker as the electric brakes as I do not think I'll ever be using loading lights on the trailer at the same time I am applying the brakes. I can always add a 2nd breaker if I find this to be not the case. The separate wiring is already there now.

The electric brakes on the trailer do not require Aux Power. Just the variable voltage on the "electric brake" wire. The brake controller up in the cabin varies this voltage based on the required need.

Running a separate ground wire to the rear for the electric brakes was not required for my installation the White wire in the factory harness is heavier than the rest of the wires and goes directly to chassis ground (somewhere). Seems to work just fine. YMMV. I hope this helps.

 

Most electric brake systems have a back up power source for emergency braking in case of detachment from tow vehicle. This is usually a small 12 volt battery attached to the safety lanyard and it requires a power source (Red 14 gauge or larger) or The trailer brake wire (Dark blue 14 gauge or larger). The light blue wire (aux, stop lamp ) and light green (reverse lamps) are not used in the seven pin connector. Hope this helps. brown-tail/park, yellow- driver turn/stop,dark green-passenger turn/stop white-ground