Questions About Factory Brake Controller Wiring

[Chevrolet1]

On a 98 Silverado model without factory tow package, are the wires included for a brake contoller?

 

I read on this forum about a blue and white wire near the underhood fuse box and another wire under the dash (for the brake switch), but need to know if these are on all 98 models or only those with factory tow package. Don't want to run all the extra wires myself unless necessary.

[Chevrolet1]

On a 98 Silverado model without factory tow package, are the wires included for a brake contoller?

 

I read on this forum about a blue and white wire near the underhood fuse box and another wire under the dash (for the brake switch), but need to know if these are on all 98 models or only those with factory tow package. Don't want to run all the extra wires myself unless necessary.

 

Finally had time to look under the rear of the truck today. Found a factory harness is plugged in near the end of the frame on the driver side (next to spare). Contains the traditional 4-plug wires minus the white (yellow, green, teal, brown) and the white appears to be grounded. Traced it to a traditional old style 4-plug connector that was tucked up above the spare (for boat or utility trailer). Looking closer at the wires next to the spare, I saw a heavier gauge red and blue wire looped back and taped up. Followed them to the front of the truck and found the same thing almost directly under the power brake booster. Unrwapped the front ones - there's a blue wire (brake controller) and a red wire with a loop terminal (12V to trailer). Tomorrow I'll unwrap what should be the other ends of these wires at the back. Looking good so far, anxious to get my brake controller and 7-way plug done.

[Chevrolet1]

On a 98 Silverado model without factory tow package, are the wires included for a brake contoller?

 

I read on this forum about a blue and white wire near the underhood fuse box and another wire under the dash (for the brake switch), but need to know if these are on all 98 models or only those with factory tow package. Don't want to run all the extra wires myself unless necessary.

 

Finally had time to look under the rear of the truck today. Found a factory harness is plugged in near the end of the frame on the driver side (next to spare). Contains the traditional 4-plug wires minus the white (yellow, green, teal, brown) and the white appears to be grounded. Traced it to a traditional old style 4-plug connector that was tucked up above the spare (for boat or utility trailer). Looking closer at the wires next to the spare, I saw a heavier gauge red and blue wire looped back and taped up. Followed them to the front of the truck and found the same thing almost directly under the power brake booster. Unrwapped the front ones - there's a blue wire (brake controller) and a red wire with a loop terminal (12V to trailer). Tomorrow I'll unwrap what should be the other ends of these wires at the back. Looking good so far, anxious to get my brake controller and 7-way plug done.

 

 

 

Sure enough, the blue and red looped wires were loose ends at the back of the truck as well.

 

Here's what else I found (at least on my 1998 and with the 1999-2007 era GM 7-way plug I installed):

 

Purpose - GM Color - Aftermarket color:

+12V to trailer - red - black (heavy gauge wire)

Ground - black - white (heavy gauge wire)

Right brake & turn - dark green - light green

Trailer reverse lights - light green - purple (rarely needed)

 

The other colors were consistent. Hope this helps or benefits someone else.

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Glad you're keeping us updated! 

[Chevrolet1]

OK, all done except the brake controller wire that goes to the brake light switch (only hot when brakes are applied). My 98 had the factory wiring for a 7-way contoller so I heard it should also have a wire under the dash for the brake switch (red wire on a Tekonsha Prodigy). Looked but can't find it. What color and guage wire is it? Whrere exactly is it located (pics would help)? Thanks!

[Chevrolet1]

Found a yellow decal that came with my Tekonsha Prodigy, says the brake light wire on Chevrolets is generally light blue. Trouble is, there are several light blue wires under the dash and you can't see the brake light switch (hidden behind steering column and multiple steel brackets. Called Tekonsha support. For my 98 (and possibly others e.g. 1996 - 1998), he said to locate the grey electrical panel/box under the dash and to the left of the brake pedal. One of the smaller open cavities is labeled "NAT" and has two small electrical prongs sticking out (a small blade terminal will fit on it). The one on the right can be used for your "brake" wire on a brake controller. This wire is hot (with full 12V) only when the brake is depressed. Hope this helps others, I'm now done installing mine.

[John L]

Thanks for all that great information! This is way more help to me than help that you got. I'm glad you were able to get it all sorted out.

 

kindest regards, -- John --

[Chevrolet1]

Thanks for all that great information! This is way more help to me than help that you got. I'm glad you were able to get it all sorted out.

 

kindest regards, -- John --

 

 

Welome John. I was rather determined to get this done and just learned on my own along the way. Documented most of it to help others.