Hey guys I'm relatively new to this forum so please bare with me please. I tried to search before I started a new post but i didn't find anything with my exact problem so here it goes... My truck is a 1998 GMC Sierra K2500 4x4. All the turn signals, reverse lights, tail lights and license plate lights work fine, no issues there. However, the brake lights do not work all the time. If you're driving down the road and you barely tap the brake pedal then they work fine, but if you push the pedal anymore than a light push then they don't work. I have replaced the brake light switch 2 times with the same results. I've looked at the ground which isn't terrible looking either. I have no idea why the brake lights don't work all the time. Please read all of the info before suggesting anything. I've tried help groups on Facebook but all they have been suggesting is replacing the brake light switch even after I have told them I've replaced it 2 different times. I'm at a loss, my only other idea is in the wiring somewhere but I do not have the time or really the expertise to be messing with the wiring so I would have to send it into a shop at $70/hour and I really don't have the money for that right now so I'm hoping it isn't in the wiring so if you guys have any ideas or have had this issue in your truck, please please please let me know. I'm beginning to get nervous driving my truck around when i literally have brake lights like 10% of the time.
thanks in advanced.
EDIT-- i have checked all fuses and relays pertaining to the brake lights and those are fine. also, when the brake lights do work, ALL 3 work. when they dont work, none of them come on.

 

Hate to tell you the same thing again but it's the switch. I had a new 98 back in the day and the dealership even had to put 3 on before they got one that worked. What brand are you buying? Alot of aftermarket electronics for these trucks are garbage right out of the box.

 

Also check the plug that plugs into the brake switch. It might have a loose wire or it might be making a bad connection.

 

i found my issue... the wiring is broke.. 3 out of 6 wires are broke and the other 3 have significant damage.

 

I replaced my brake switch , the relay, and the circuit board with the lights. I finally found that my truck had the same broken wire and it had the exact same symptoms the brake lights would come on for a half of a second when you tapped the brakes then go out . I can't get the other side of the wire that connects to the brake switch unplugged to save my life how did you get in there to get it out ? I can barely get my middle finger to touch it when I contort my hand up . Is there something you were able to remove to get better access? Also it feels like something is holding that connector in place but I can't see what it is to get it loose. What is the part name or number for this wire I can't find a name to know what to ask for ? I was barely able to get the wire around the front of the steering column. I can't believe I have spent hours under the dash trying to detach that thing so far and can't seem to get it.

 

Well actually after lying on my back for hours and trying with everything I had my wife said let me try and so I described what it looked like and she reached under there and in 3 seconds she pulled it out