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Brake light won't come on when headlights are on

Discussion in 'Cherokee' started by JEFASOLD, Aug 18, 2017.

  1. Aug 18, 2017 at 9:12 PM
    #1
    JEFASOLD

    JEFASOLD [OP] Member

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    Ok, here is my problem. My left rear brake light works when my lights are not on, ie: daytime but when my lights are on, it goes out when I apply the brakes. I tried changing the brake light switch to no avail. Any ideas?
     
  2. Aug 18, 2017 at 10:14 PM
    #2
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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    Sounds like a bad ground.
     
    JKBob 25, aggrex and Bob like this.
  3. Aug 19, 2017 at 6:23 AM
    #3
    OFFGRID

    OFFGRID Well-Known Member

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    I have been thinking about this sense you first posted a while back. I am thinking that your light switch is shorting out. You may need a new switch. Dead horse jeeps a vendor on eBay that specializes in used parts will probably have one. Also check this page from Morris4x4center. If you have a wiring diagram of the light switch I would try to test the switch with a test light before spending $85 on a new switch. Dead horse guarantees their parts buy sending you another one if the one you got is bad.


    https://www.morris4x4center.com/search/?q=Light+switch
     
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  4. Aug 19, 2017 at 7:41 AM
    #4
    JEFASOLD

    JEFASOLD [OP] Member

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    What light switch are you talking about? Location?
     
  5. Aug 19, 2017 at 8:42 PM
    #5
    JEFASOLD

    JEFASOLD [OP] Member

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    Correction on the brake light, it does not work when the lights are off, only the low level stage 1. So the brake light does not work. I think I'll try a replacement switch, $33 on Ebay.
     
  6. Aug 19, 2017 at 8:46 PM
    #6
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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    If that's the case, I would try a different bulb. Its not uncommon for the brake light filament to break, while the regular light filament remains intact.
     
  7. Aug 19, 2017 at 10:06 PM
    #7
    OFFGRID

    OFFGRID Well-Known Member

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    Lets get back to basics.

    1. You should have both break lights (bright) and running lights (Dim) in the back.
    2. Your say your break lights do not work when all lights are off.
    3.. You say that when the lights are on the running lights come on but the break lights don't work (is this what you are saying).

    Do your Blinkers work in the back?
    First the cheapest thing to do is replace all light bulbs in the rear of the car. Will cost you maybe $15. you will then know that everything is good there. A clean slate.

    Break lights may not work if:

    Fuse is blown.
    Relay (if you have one) is blown
    Break pedal switch is malfunctioning
    Head light switch is malfunctioning
    Turn signal switch is malfunctioning (Very rarely happens)
    There are other things, but also not likely.

    I would follow my list above in order. You can test all of these things with a test light and a wire diagram. Have patience and look for power coming from each switch going to the bulbs. If you find you are not getting power from a switch then it is likely the culprit.

    Also check to make sure your rear lights are grounded or they wont work.
     
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  8. Aug 19, 2017 at 10:08 PM
    #8
    OFFGRID

    OFFGRID Well-Known Member

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    In light of your correction hold off on purchasing that switch. follow the above post.
     
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  9. Aug 20, 2017 at 7:16 PM
    #9
    JKBob 25

    JKBob 25 Well-Known Member

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    I am in no way an expert in electrical issues. But I do follow issues posted here. Just looking to learn. And OFFGRID is probably our best here with electrical issues.

    Subbed.
     
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  10. Aug 21, 2017 at 10:54 AM
    #10
    JEFASOLD

    JEFASOLD [OP] Member

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    The brake light works on the right side, so a fuse or relay would not be the problem. Bulbs have been changed several times. So, probably a ground or the switch, right?
     
  11. Aug 21, 2017 at 10:56 AM
    #11
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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    Take the bulb that works, and swap it in to rule it out for certain.
     
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  12. Aug 21, 2017 at 11:14 AM
    #12
    OFFGRID

    OFFGRID Well-Known Member

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    What Chris said. If your break light is working on the right then it's not a switch. Bad bulb or ground would be the likely culprit. Possibly the bulb is not making contact. Bulbs are grounded to the housing and the housing is either grounded to a common ground or to the frame.

    Does your left blinker work? The left blinker and left brake I think are the same.
     
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  13. Aug 21, 2017 at 11:41 AM
    #13
    JEFASOLD

    JEFASOLD [OP] Member

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    The left turn signal works. Driving light works. Backup light works.
     
  14. Aug 21, 2017 at 5:53 PM
    #14
    OFFGRID

    OFFGRID Well-Known Member

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    I just looked at some pictures of some 2002 GC. It looks like your year has seperate blinker and brake lights. Try putting a known good bulb in their and see if that fixes your problem.
     
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  15. Aug 27, 2017 at 7:30 PM
    #15
    JEFASOLD

    JEFASOLD [OP] Member

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    I have tried a brake light switch, a headlight/turn signal switch and changed bulbs multiple times. Leftn rear brake light still doesn
    t work. Does this forum have a service manual to download?
     
    JKBob 25 likes this.
  16. Aug 27, 2017 at 7:41 PM
    #16
    JKBob 25

    JKBob 25 Well-Known Member

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    Sorry dude. We don't have service manuals to download. Your going to have search manuals in the Chrysler, Fiat, Jeep, websites. I know...a pain in the ass. That's how I got my Manufactures Manual. Sorry.
     
  17. Aug 27, 2017 at 7:45 PM
    #17
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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  18. Aug 27, 2017 at 8:11 PM
    #18
    JKBob 25

    JKBob 25 Well-Known Member

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    Sorry Chris4x4. But I clicked the link. And it turned out to be a link for a fair act forum for farm equipment repairs and such. Before I take this any further. Have you been "amusing" yourself, and just got distracted?. Then all is good. Just checking. You ok.....:drool:
     
  19. Aug 27, 2017 at 8:12 PM
    #19
    chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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    What? Link goes directly to the WJ Service manual .
     
  20. Aug 27, 2017 at 8:15 PM
    #20
    JKBob 25

    JKBob 25 Well-Known Member

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    Not the link I hit up. It's a link if you want to file a complaint. And sue.
     
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