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more brake light issues

Discussion in 'Flat Fender Tech' started by 97XJ_95YJ, Dec 11, 2007.

  1. 97XJ_95YJ

    97XJ_95YJ I hate torx bolts

    Okay. I got all of my lights working except for the break lights. Now, tell me if my theory is correct:

    Theory: Just to test things, I ran a wire directly from the battery + terminal to the upper post on the break light switch, which is hooked to the master cylinder. I ran a wire from the second post on the break light switch to the test light. I ran a third wire from the test light ground to a ground on the Jeep (body mount bolt that I've used to test grounds before). When I hit the break pedal the light should light up, right?

    Well it doesn't. I tried a few different ground locations with no success. I also tried to switch posts on the stop light switch, with no success. So, does this mean that the stop light switch is bad? Any other suggestions?
     
  2. jeepfreak81

    jeepfreak81 When in Doubt, Pedal out!

    Re: more break light issues

    IIRC the switch is under $12 I would just replace it and be sure. These old jeeps only had one switch.

    But it sounds like it may be bad anyway. One side of my switch goes to 12V the other side directly to the brake light wire on the tail light, obviously the tail light is grounded to the frame/body.
     
  3. 97XJ_95YJ

    97XJ_95YJ I hate torx bolts

    Re: more break light issues

    Yeah. I'm thinking the switch is bad. How are your wires connected to the switch?

    Stupid question, but I never replaced this switch before in any vehicle, I believe it just screws on the end of the MC. When I remove it, should I expect break fluid to come gushing out at me?
     
  4. Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Re: more break light issues

    when you connect test light aligator clip to ground and touch the pointy end to the post on stop switch where you have the battery wire connected did you confirm that you had power going to the switch? if so then you continue with your sw check.
     
  5. 97XJ_95YJ

    97XJ_95YJ I hate torx bolts

    Re: more break light issues

    No. I didn't test that. I just assumed the power connection was okay. I guess I should have checked that.
     
  6. 97XJ_95YJ

    97XJ_95YJ I hate torx bolts

    Re: more break light issues


    Okay. I did that and the test light worked. I then ran the wire to the stop light switch and it didn't work. So...I'm guessing the switch is bad. Is replacing one of these as simple as unscrewing it from the master cylinder and screwing the new one on? Should I expect break fluid to come gushing out at me when I remove it?
     
  7. Glenn

    Glenn Kinda grumpy old man Staff Member

    Re: more break light issues

    A bit might run out, but it won't rapidly pour out. Just change it out quick and you should be fine. Obviously top the M/C back off. I don't think you would even have a problem with any air in the lines either.
     
  8. w3srl

    w3srl All-around swell dude Staff Member

    Re: more break light issues

    :iagree:

    If you have turn signals in the Jeep, the power lead for the brake lights comes from the TS switch instead of directly from the battery. ;)
     
  9. 97XJ_95YJ

    97XJ_95YJ I hate torx bolts

    Re: more break light issues

    Actually my turn signal switch is the Signal-Stat 902 model and it doesn't include break lights. It's strictly for turn signals. So, I have to mount a second set of lights to have all the lights I need.
     
  10. mike starck

    mike starck Member

    Re: more break light issues

    do you have turn signals or seperate lights for turn signal and brake.inquiring minds want to know.


    mike s.
     
  11. mike starck

    mike starck Member

    Re: more break light issues

    actually the 12v source for brake light switch comes from the battery.constant 12v.brake lights work allways when switch is off.turn signals use switched 12v source.clear as mud?
    mike s.
     
  12. w3srl

    w3srl All-around swell dude Staff Member

    Re: more break light issues

    That's not 100% correct Mike, if the turn signals use the same filament as the brake lights, the power for the brake lights comes from the TS switch. Otherwise, when you hit the brakes there would be no TS indication.

    As mentioned, the 4-wire TS setup requires a second separate bulb to be used for the TS indicators, a 7-wire system can use the same bulb for both. The 7-wire setup supplies power to the brake light circuit, the 4-wire does not.
     
  13. mike starck

    mike starck Member

    Re: more break light issues

    yes it is 100% correct.if you don't understand how the system works do some researchh.

    mike s.
     
  14. w3srl

    w3srl All-around swell dude Staff Member

    Re: more break light issues

    I stand corrected, the power goes TO the brake light switch, THROGH the TS switch and THEN to the TS/BRAKE lamps with the 7-wire system.

    [​IMG]
     
  15. w3srl

    w3srl All-around swell dude Staff Member

    Re: more break light issues

    A 4-wire system works completely independent from the brake lights.

    [​IMG]
     
  16. 97XJ_95YJ

    97XJ_95YJ I hate torx bolts

    Re: more break light issues

    Yup. I have the 4-wire system.
     
  17. w3srl

    w3srl All-around swell dude Staff Member

    Re: more break light issues

    The color of the wires may be off, but the second diagram should get you up and running again.
     
  18. 97XJ_95YJ

    97XJ_95YJ I hate torx bolts

    Re: more break light issues

    I'm all good on the turn signal issues now. I have all of the lights working except for the stop lights. I'm going to mount a second set of lights to act as break lights only. I'll probably just use some red marker lights or something. However, I'm pretty sure my break light switch on the master cylinder is shot and needs replaced.
     
  19. Glenn

    Glenn Kinda grumpy old man Staff Member

    Re: more break light issues

    The size of the light might be an issue, so you might consider getting normal size lights for the brakes also. If they look like a marker light people might not realize they are the brake lights.

    Whatever you use has to accept bulbs that are for brake lights, i.e. they have the brighter filaments.
     
    Last edited: Dec 12, 2007
  20. 97XJ_95YJ

    97XJ_95YJ I hate torx bolts

    So I can't just use any standard marker light for my break lights?