2004 Suburban/Chevy truck wiring info

[Silvertwinkie]

Ok, to hear the GM folks tell it, there is suppose to be a pigtail connection (for the brake control) under the left driver's side well (under the dash). I have found one thing that looks taped up not really looking like the thing that connects to the pigtail and then I found a junction box under there. There are several connections in this junction box. One says trailer 6 way (brown). This looks like the place to connect it which is different than the diagram (as I had to remove a panel,flimsy plastic door to get to the junction box. The issue here is that all the labels for the other plugs (white, brown, black, beige) all match. The pigtail connector is white (junction box connection is labeled brown).....and yes, the truck does have the tow package.

Anyone out there point me in the right direction of where the heck GM put the brake control pigtail connection under the dash.

Thanks.

[Pahaska]

To the right of my parking brake and left of the brake pedal, on the firewall, there is a bulging black cover that is held on by a long plastic nut. Behind that cover, the brake controller plugs in at the top center of the panel behind that cover.

When I first plugged in the cable that I had used on my 2000 Silverado, the brake controller didn't work. A little checking showed that Chevy had switched two of the pins in the connector between 2000 and 2004. When I mentioned ythis to the dealer, he got a sheepiish grin and allowed as to how they get a lot of questions and gripes about the change.

[Silvertwinkie]

Thanks John. The diagram they show has it looking like a somewhat loose connector, without any mention of the junction box.

Also, thanks for purging that other duplicate thread (if it was you). I hit the stop button by mistake mid way through.

[john hd]

eric

john has it right, center connector top of the junction box.

when you wire your brake controller make sure you leave enough wire to tuck it well up and out of the way. otherwise you may catch it on your shoes when getting in and out.

also, directly under the center of the dash there are pre punched holes that make a nice spot to mount the controller.

use good quality connectors or solder the pigtails together and you should be good to go!

p.s. don't forget to install the mega fuse that is taped on the factory pig tail into the B-2 slot in your under hood fuse block! don't panic if you don't have one, i have heard that some trucks have it already installed from the factory.

john

[Silvertwinkie]

Originally Posted by john hd

eric

john has it right, center connector top of the junction box.

when you wire your brake controller make sure you leave enough wire to tuck it well up and out of the way. otherwise you may catch it on your shoes when getting in and out.

also, directly under the center of the dash there are pre punched holes that make a nice spot to mount the controller.

use good quality connectors or solder the pigtails together and you should be good to go!

p.s. don't forget to install the mega fuse that is taped on the factory pig tail into the B-2 slot in your under hood fuse block! don't panic if you don't have one, i have heard that some trucks have it already installed from the factory.

john

Hey John,

Thanks for the tip. I sent you a PM, but later found that the pigtail does have a 40a fuse taped to it. Also, I found that the fuse box in our truck (underhood) labels the fuse location as "Stud-1". Stud 2 looks like the actual fuse for the trailer brakes and is already populated. The Stud-1 is currently just a red cap waiting for the factory supplied fuse to be installed from the pigtail.

Interesting that the pigtail has a note on it that if you have dual batteries, you blow off the fuse since it's not needed. If you don't have the dual batts (as I don't), you must populate the Stud-1 with the supplied 40a fuse.

This all lead me to an important find. These are different type fuses than anything else I have ever used. It might not be a bad idea to add a few of these to the ol' toolbox.

[john hd]

eric

here is a pic of it.

it is the green one on the left. be aware that mine may be different than yours since GM changed the layout of the under hood fuse center after 2001.



john

[Silvertwinkie]

You the man John! Thanks for the pic. Helps a bunch just seeing it to help understand the logic GM used with this.

GM has changed the config quite a bit from that pic, but the pic is still helpful. The fuses are now very small and square. The junction box is still the same under the dash, but the underhood is night and day. I'll post a pic here at some point to show the diffs.