I recently purchased a used 01 Blazer with ~83.000 miles on it. The previous owner(s), apparently, did not use the trailer wiring harness as I found it coiled and straped to the frame under the rear bumper. I peeled the tape off and found seven wires in the harness. Two of them were heavier gauge, they were red and blue. The red wire is the hot one, the blue is the trailer brakes. There were five smaller gauge wires, they were brown, yellow, dark green, light green, and light blue. The brown is taillamps/parking lamps, yellow is left stoplamp/turnsignal, the dark green is right stoplamp/turn signal, the light green is back-up lamps, and the light blue is the auxiliary stoplamp (according to the owner's manual).

Based on this information, it seems to me I should be able to hook up a brake controller and wire a 7-pin RV plug to the harness. However, the chevy dealership I called and asked said that it was not possible. I'm sure it is possible, so could someone tell me where I would wire the brake controller into? Is there a place I can plug a harness into to wire my brake controller to, or do I have to tap into the fuse box, the brake lights, and the brake wire individually? If I do have to do it individually, where does the brake wire from the harness come into the vehicle? In short, I'm sure someone out there has wired it up before, so could they please tell me how? Any help is greatly appreciated in advance. Thanks!

 

You're owners manual should have the wiring diagram in it. I'm not sure of where the wires for the brake controller go to from the back of the vehicle, but I have a 7pin connector on my Bravada (actually, a 4pin and 7pin connector). At this time, I do not have a brake controller. The manual also does not state anything about how to install a controller.

A manual for your '01 can be found here:
2001 Chevy Blazer Owner's Manual

You will need to look in section 4 to find the towing section. Here's the page of interest:
If the trailer harness goes up into the passenger compartment like it should, there should be atleast one wire under the dash on the driver's side to use as the main power wire to the trailer. Good luck.

 

It is possible to wire a seven pin connector. The large blue wire is the hot line out from the brake controller to the connector. You should find the other end under the dash on the drivers side or above the tranny hump, they keep changing locations, so you may have to search a little. Brake controllers have there own individual plug designs, so there is not a plug on your blazer that will plug into the brake controler.

A brake controller is normally wired as follows. The hot wire would come off the battery to a fuseable link then from the fuseable link to the brake controller. The ground, well can be attached anywhere but preferably a direct line to the battery (so the controller does not share power with anything else). The last line will be wired to the brake pedal switch. Note; the hot and ground should use 12 or 10ga wire.

I have heard that some vehicles already have the hot "in", the ground, brake switch, and the hot "out" already connected in a bundle under the dash, which would make things real easy for you and you would just have to splice into the harness from the brake controller.

When you are making any sort of wire connection you should always solder the wires together, put some dielectric grease on,and heat shrink the connection (this includes the inside and connections of the plugs. Many times people will use taps, butt connectors etc. these can work them selves loose and are prone to corrosion.

Don't forget a heavy duty flasher for your turn signals.
Just some extra info trailer wiring codes are not the same as veh. wire codes. Here are the trailer side codes.

1) white - ground
2) blue - brake
3) green - tail/running
4) black - power/batt. charge
5) red - stop/left turn
6) brown - stop/right turn
7) yellow - aux.circuit/backuplights