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'91 CV no taillights during breaking

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    '91 CV no taillights during breaking

    So, the taillights work for turn signals, hazards, however when I step on the break only the high mount/3rd brake light illuminates. Fuses/bulbs appear intact, id assume its not the break light switch as the 3rd brake light illuminates. Any ideas ? Thanks for any tips.

    #2
    This is most likely a problem with your turn signal switch (multifunction switch), and more specifically, probably the hazard function of the switch.

    Because the turn signals and brake lights share the same bulb, the turn signal switch (or hazard switch) has to interrupt the brake light voltage to enable the voltage to be cut on and off by the flasher. Since your problem is both sides, I suspect the hazard switch.

    Aggressively pull out and push in the hazard switch a few times, and re-test. If the problem is gone, now it may be fixed for a while, or maybe forever. If it does not work, my next step would be to inspect the wiring at the turn signal switch, and consider replacing it.

    If it did work, I'd then try to make it break again by doing things like wiggling the hazard button or smacking the bottom of the steering column. If the lights stop working again, I'd replace the switch even if you can wiggle it into working again.

    Panthers: 83 GM 2dr | 84 TC | 85 CS | 88 TC | 91 GM
    Not Panthers: 85 Ranger | Ranger trailer | 91 Acclaim | 92 Jaaag | 05 Focus
    Gone: 97 CV | 83 TC | 04 Focus | 86 GM
    | Junkyards

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      #3
      Originally posted by kishy View Post
      This is most likely a problem with your turn signal switch (multifunction switch), and more specifically, probably the hazard function of the switch.

      Because the turn signals and brake lights share the same bulb, the turn signal switch (or hazard switch) has to interrupt the brake light voltage to enable the voltage to be cut on and off by the flasher. Since your problem is both sides, I suspect the hazard switch.

      Aggressively pull out and push in the hazard switch a few times, and re-test. If the problem is gone, now it may be fixed for a while, or maybe forever. If it does not work, my next step would be to inspect the wiring at the turn signal switch, and consider replacing it.

      If it did work, I'd then try to make it break again by doing things like wiggling the hazard button or smacking the bottom of the steering column. If the lights stop working again, I'd replace the switch even if you can wiggle it into working again.
      QFT. This. Known issue with all vehicles with this type of setup (Re: American vehicles).

      Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
      rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)

      Originally posted by gadget73
      ... and it should all work like magic and unicorns and stuff.

      Originally posted by dmccaig
      Overhead, some poor bastards are flying in airplanes.

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        #4
        I was just dealing with a similar issue on my '78 LTD wagon. I second the multifunction switch. You can see how the brake light feeds through the switch on the wiring diagram. The switch isn't setup the same as on my LTD, but the circuitry is pretty similar still.
        1978 Ford LTD wagon, 351M
        1979 Mercury Marquis, 351W
        1987 Ford F-250 HD 4x4, 460, 4-speed, reg cab full bed
        2003 Mercury Marauder, 4.6L DOHC, JLT CAI, 4.10 gears, J-mod, custom tune

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          #5
          It’s funny because I Just replaced that multifunction switch twice lol. The original was cosmetically not great. Purchased an NOS one via eBay however that one acted funky. Headlights only worked on high beam. So got an aftermarket multi switch, and this is the issue I’m getting from the 2nd new switch…lol

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            #6
            Originally posted by Hill185 View Post
            It’s funny because I Just replaced that multifunction switch twice lol. The original was cosmetically not great. Purchased an NOS one via eBay however that one acted funky. Headlights only worked on high beam. So got an aftermarket multi switch, and this is the issue I’m getting from the 2nd new switch…lol
            Can you find an OEM switch?
            What I Own: 1993 Mercury Grand Marquis GS
            What I Help Maintain: 1996 CV / 1988 CV / 1988 Tempo

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              #7
              Originally posted by Hill185 View Post
              It’s funny because I Just replaced that multifunction switch twice lol. The original was cosmetically not great. Purchased an NOS one via eBay however that one acted funky. Headlights only worked on high beam. So got an aftermarket multi switch, and this is the issue I’m getting from the 2nd new switch…lol
              Can you find an OEM switch? May or may not be at a reasonable cost but may be the best move as opposed to buying several aftermarket ones.
              What I Own: 1993 Mercury Grand Marquis GS
              What I Help Maintain: 1996 CV / 1988 CV / 1988 Tempo

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                #8
                It’s funny, the first replacement switch was NOS OEM Ford part. But I may try and find another and see what happens.

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                  #9
                  Was the OEM you bought new or used?
                  What I Own: 1993 Mercury Grand Marquis GS
                  What I Help Maintain: 1996 CV / 1988 CV / 1988 Tempo

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                    #10
                    check the connections, maybe something is loose. Since the third light works, the brake light switch itself must be OK, and the signal is failing between the brake light switch and the output from the multifunction. I don't know if there is a connection between the brake light switch and the multifunction switch to check.
                    86 Lincoln Town Car (Galactica).
                    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                    91 Lincoln Mark VII LSC grandpa spec white and cranberry

                    1984 Lincoln Continental TurboDiesel - rolls coal

                    Originally posted by phayzer5
                    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

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                      #11
                      This was the issue thank you! Popped the the steering column cover off, checked and reinstalled, taillights now operate and intended. Thanks again

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