1999 GMC Sierra rear brake lights out(3rd works) I have searched..

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by mohamie, Sep 28, 2011.

  1. mohamie

    mohamie New Member


    New to the forum, thanks for having me [​IMG]

    I have performed a forum search for my problem. But could use a little more guidance if someone would lend a hand, I would appreciate it.

    In addition to what the title says I should add that I have aftermarket LED rear lights. The lights work up front, the back parking lights, turn signals and hazards all work. Just not the brake lights on the tail lights. Turn signals use the same LED's that the brakes do. No blown fuse. Got the test light out and started poking around. The wires coming off of the switch on the brake pedal all made the test light light up. All had power without pressing the brake, except for one, it had power when the brake was pressed. Then I got under the bed where the buss is, unplugged the one coming from the cab. Test light never went off when the brakes were pressed.

    After searching the forum I read a reply from crabtruck that mentioned a relay. He said when you press the pedal you should hear the relay click. I don't hear that. That combined with the previous testing I have done would point to that. Problem is I can't find it anywhere. Following the wires quickly went into a rabbit hole. And my searching for this relay has gone for naught.

    Could someone help me find this or tell me I'm looking in the wrong place?

  2. silveradotrailblazer

    silveradotrailblazer Epic Member 5+ Years ROTM Winner 5000 Posts

    Welcome to the club. Sorry I can't help you but I'm sure someone on the site can.
  3. mohamie

    mohamie New Member

    hey, thanks anyway
  4. drm223

    drm223 New Member

    I had the same problem on my 2000 silverado. My solution was pulling off the bed (it was easier) and just where the cab and bed meet up should be a plug setup for your rear lights. i bypassed the entire thing and hardwired it all. didnt have a problem after that
  5. sstoner911

    sstoner911 Epic Member 5+ Years 1000 Posts

    You say the 3rd brake light works? Did the LED brake lights work at one time or did this start with the addition of the LED tails? I have seen some after market tails not have load resistors and this causes issues.

    If these lights have worked before I would double check your fuses..not sure if the 99's have fuses under the hood but the fuse should be labled STP LAMP or something like that.
  6. mohamie

    mohamie New Member

    I have had them working for 6 months or so. I will check, thanks!
  7. Jeff Demme

    Jeff Demme New Member

    Newbie here... did you ever resolve this problem? I have same problem. Third brake light works, the other two do not. All bulkbs and fuses OK. Turn signals and running lights work. Is there a relay?
  8. j cat

    j cat Epic Member 5+ Years 1000 Posts

    if this is NBS the brake tail lights do not work but the high center brake light does. this means that the brake switch is good and all that area. my guess is the feed at the rear under bed is screwed up. there is a circuit board and connectors under that get corroded up and burned up...use a stick hold pedal down then use a meter NOT TEST LIGHT.. The meter will show any voltage drops..also check the ground wire..
  9. RAV52202

    RAV52202 Rockstar 100 Posts

    I second on jcat. I had problems with my tail lights and it was the circuit board under the bed in the back. I had one side that was all corroded. Replaced board and all worked after.
  10. redvett

    redvett Rockstar 100 Posts

    There are two separate circuits one for the CHMSIL and the other for the rear brake lights. The brake switch has several outputs and the rear brake lights go first to the turn signal switch for Lh & Rh and four ways.

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