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Intermittent Brake Light Issue

Discussion in 'Early CJ5 and CJ6 Tech' started by Cj5dale, Sep 25, 2021.

  1. Sep 25, 2021
    Cj5dale

    Cj5dale Member

    East Tn
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    I am experiencing an intermittent issue with my drivers side brake light on my 1970 Cj5.

    Sometimes it just doesn’t work. Other times it does.

    I know that wiring circuit runs through the spartan turn signal switch. So one time when it had stopped working, I operated the turn signal switch very rapidly for several times. After doing that, the brake light started working again. That lasted for a while then it stopped working again.

    This morning I took the light switch apart expecting to find a loose connection. However, all the connections are solid. I was afraid to open up the actual internal switch mechanism so I haven’t done that.

    Any suggestions?

    Thanks again for your help.
     
    Last edited: Sep 25, 2021
  2. Sep 25, 2021
    Twin2

    Twin2 not him 2021 Sponsor 2020 Sponsor

    Virginia Beach, VA
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    a test light will tell if the light is getting power
    grounds seem to be a issue with lights
     
  3. Sep 25, 2021
    colojeepguy

    colojeepguy Colorado Springs

    At the foot of...
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    That was my 1st thought as well.
     
  4. Sep 25, 2021
    Cj5dale

    Cj5dale Member

    East Tn
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    I’ll do the test light the next time it fails. That’s probably what’s going on.

    I was thinking that since it seems to get corrected when I operate the turn signal switch repeatedly that it might be something going on there.

    Thanks for your suggestions.
     
  5. Sep 25, 2021
    55_Willys_CJ5

    55_Willys_CJ5 Nephews Visit 2017 2020 Sponsor

    Southern California
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    As Twin2 stated and colojeepguy endorsed - check the ground.

    Most electrical issues with our jeeps are usually the result of a grounding issue (Bad, broken, or intermittent).

    Recommendation

    1. Check ground - Test light or ohm meter
    2. Check all connections for looseness (Hardware, connectors, bulbs, etc...)
    3. Check wiring condition - Intact, no crumbling or deteriorating of insulation (Possibly exposing wire and causing a short in the run)

    If the above steps don't resolve the issue then consider taking the turn signal switch apart. Decent write-up here: Jeep Trucks: Rebuild Guide (jeep-trucks.com) If the switch has been on the jeep since new then you could have 50+ years of build up inside and could be the issue.

    I had a front turn signal not operating correctly and took the spartan switch completely apart and checked everything. After reassembly and install, the turn signal issue wasn't fixed. The last step, which should have been my first, was a test light on the battery ground post to turn signal light housing, when I did this the light worked as required. Fix - grounded the housing and works as required. I spent hours checking connections, wire routes, connectors, hardware, etc..) If I would have checked the grounding first, I would have fixed the problem in 30 minutes.
     
  6. Sep 25, 2021
    Fireball

    Fireball Well-Known Member 2021 Sponsor 2020 Sponsor

    Pullman, WA
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    The internal switch is pretty easy to take apart. You can see it on this posting in my build thread: Old Red Maintenance Thread

    Mine needed the contacts cleaned and one of the springs keeping pressure on the contacts had collapsed. Probably because the dirty contact got hot.
     
  7. Sep 25, 2021
    Cj5dale

    Cj5dale Member

    East Tn
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    I have a multi-meter I can use. I’ll confirm the wiring/connections/ground before I attempt messing with the internal switch.

    Thanks again for sharing your experience and lessons learned with these jeeps. Much appreciated.
     
    Fireball likes this.
  8. Sep 25, 2021
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2021 Sponsor 2020 Sponsor

    Hills of NH
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    I would check and and ensure all the connections and grounds at the tailight - bulb, socket, contacts, housing to body - before you go nuts pulling the switch apart
     
  9. Sep 25, 2021
    Cj5dale

    Cj5dale Member

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    I’m assuming the ground at the housing is done through the bolts attaching it to the tub. The housing is completely painted.
     
  10. Sep 25, 2021
    Cj5dale

    Cj5dale Member

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    This is an awesome thread!
     
    Fireball likes this.
  11. Sep 25, 2021
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2021 Sponsor 2020 Sponsor

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    ...and you can assume it may be corroded.
     
  12. Sep 25, 2021
    Cj5dale

    Cj5dale Member

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    Good point. I’ll clean up those too while I’m checking the connections
     
  13. Sep 25, 2021
    Fireball

    Fireball Well-Known Member 2021 Sponsor 2020 Sponsor

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    Thanks! It's been fun documenting it and I use the thread often to go back and remember what I did.
     
    Cj5dale likes this.
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