Fast Flashing Turn Signal

Discussion in '2005+ Mustang GT 4.6L Tech' started by Terry, Jan 11, 2019.

  1. Terry

    Terry Junior Member

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    Hi Guys,

    My right hand turn signal has started flashing quickly. To be clear it flashes quickly most of the time but occasionally will revert back to normal. But mostly it flashes quickly with small intermittent normal flashes, enough to think it might be fixed...until it starts again.

    I have checked all the bulbs and they are working fine but in any case have swapped them out with the left hand bulbs to be sure one of them wasn't faulty in same way. No cigar. I also checked for loose wiring in case an earth issue was present. Have checked for thrown codes. Nothing thrown. Have checked that the bulb to housing connection is good on all right hand turn signal lights and not causing resistance. (Note I have the European lighting with amber front turn, amber rear turn, and amber fender mounted turn). I have sprayed all three bulb/housing connectors with contact cleaner. No improvement. I have checked all the fuses in the engine fuse box and the SJB. All fuses are good. Have swapped out the relay in the SJB with one from the engine fuse box. Still no cigar.

    Now I understand that the SJB controls the turn signal rather than a separate flasher unit, so I'm guessing I am left with the possibility of a faulty SJB or a dodgy earth somewhere in the labyrinth of wiring. Any thoughts/suggestions?

    Cheers

    Terry
     
  2. Juice

    Juice forum member

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    SJB is detecting a bulb out. Check when it is flashing fast. Bulbs can have a broken filament that intermittently "reconnects" after hitring a bump/closing the trunk, etc.
     
  3. nbk13nw

    nbk13nw forum member

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    Same issue here as well. 2005 GT. Drivers side rear blinker hit and miss. Works fine then acts up. Switched bulbs with the passenger side same issues. New bulbs same issues. Been working fine for the last week or so.
     
  4. 01yellerCobra

    01yellerCobra forum member

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    Does weather affect it? My truck had a light that would act up when it was wet outside. It finally blew out, but it would work fine for a while then blink fast randomly.
     
  5. Juice

    Juice forum member

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    When it is blinking fast, do NOT turn off turn signal. Pull over, get out, and walk around to see which bulb is not lit/flashing.
     
  6. skwerl

    skwerl tree hugger

    15,226
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    It probably isn't applicable here, but I recently had a similar issue with my 2002 F150. RR tail light went out and it wasn't the bulb. After a few months it started working again. Worked for a year and went out again. Worked sporadically for a few months then quit altogether. Checked the wiring as far forward as the trailer pigtail under the bed, no juice to the RR turn/brake light. Had my mechanic check it out and he traced it to the turn signal switch on the steering column. Replaced the universal switch and everything is perfect again.
     
  7. Terry

    Terry Junior Member

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    Thanks guys. The car is only taken out on sunny days and spends the rest of its life in a closed garage. Apart from when it is washed, there is no opportunity for water to get in and the carpets are certainly dry. I do understand however, that water ingress has been an issue for some and lighting and other erratic issues have been associated with the SJB getting drenched and corrosion setting in. But in my case, moisture doesn't seem to be the case.

    The bulb going bad theory (partially broken filament etc) I think I might have discounted by swapping out the bulbs with known good ones from the left hand side.

    There is no problems with all the bulbs working. I have walked around the car a hundred times with the turn signal fast flashing to see if I can detect a faulty bulb or one that only intermittently works but no luck. They're all working fine.

    Here's something odd to add though. On one walk around with the turn signal flashing fast I took a bulb out just to see what would happen. Nothing happened. It continued flashing fast and then intermittently flashing normally, then fast again. So it didn't seem to recognise a bulb had been removed!!!

    Actually skwerl, the multi-function switch may be something I should look at. I hadn't even thought about that since it works as expected that is you turn it on and the indicator flashes, usually fast. But maybe there's some dust or dirt that that's messing with the terminal resistance? If terminal resistance is a trigger. I'm not sure how this computer controlled flasher works really. The old separate flasher relays were quite simple to diagnose in comparison.

    Thanks for your suggestions guys.

    Terry