Brake light

Maelrio1 · **Joined:** Thu Oct 13, 2011 3:36 pm **Posts:** 12

Hi, today my colleague means, that on my KK only the 3rd brake light works. I check the bulbs on both side, seems to be okay, the brake switch works also, cause the 3rd light works. Are there some fuse or some known issues for the KK that both brake lights are not working? Before i bring it to the dealer, i ask you and maybe got some help.

Mario

At The Helm · **Posted:** Mon Jan 07, 2013 7:57 pm

Check your fuses.
Get a $3 12v tester, test the wiring in the pigtail coming out of the body to the tail lights. If that yields nothing, take it to the dealer.

At The Helm · **Posted:** Mon Jan 07, 2013 8:00 pm

Are you not getting any light at all? Those are dual filament bulbs, one for tail lights, one for brake lights.

Diggerfreek · **Posted:** Mon Jan 07, 2013 8:35 pm

My bets on the bulbs as well

Gageraid · **Posted:** Mon Jan 07, 2013 9:07 pm

It's amazing how popular it is these days to see someone with one or more brake lights out. From my experience, it's rarely a Jeep.

Scar0 · **Posted:** Tue Jan 08, 2013 5:20 am

Word of caution!
Don't play with the brake light switch at the pedal!
If the brake light switch comes off the pedal, or becomes maladjusted, it will have to be replace.

Further information on the brake light switch;
It has an internal ratchet/cam that adjusts out to your brake pedal location when first installed. This sets the "light off" position of the switch. From this location it has a set distance of inward travel before sending the signal to the TIPM to turn on the brake lights (turn off the cruise control, and release the shift lever when in park).

If the brake light switch comes off the brake pedal arm, the internal spring forces the switch piston to the full out position. What this does is to set the "light off" position at the full out location of the ratchet/cam, locking it there (you can not reset it). Any compression of the switch position past the "set travel" to signal the TIPM to turn on the brake lights will cause them to come on.
So, if it is reinstalled after this happens, your brake lights will be on at all times.

The third brake light is on its own circuit. The CHMSL receives battery voltage directly on the brake lamp switch output circuit when the brake lamp switch is closed by the brake pedal arm. The TIPM also receives battery voltage on the brake lamp switch output circuit, which it uses as a logic input to energize the brake lamps. The TIPM provides battery voltage to the brake lamps through two high side drivers on the tail/stop lamp rear feed circuit when it receives the proper input from the closed brake lamp switch.

So, check for power at the taillight wires when the pedal is depressed. If there is no power at the light, then the issue is most likely with the switch.
If you have power at the wires, make sure you use the exact same light bulb as the stock bulb when replacing them. The "cross-reference" bulbs will not work sometimes.
Also check inside the socket for melted like buildup of gunk.

Brake light

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