Moss Motors, Ltd

I have a 1976 MGB roadster, whenever i have the front left turnsignal on and i hit the breaks it stays on but does not flash.  That and if the lights are on it stays solid too.  I checked and cleaned all the connections.  Anyone have any advise for me? 

My guess is that there is a problem in the column switch. The contacts there should remove the brake light voltage from either side if the turn signal is on that side. Sounds like that function isn't working correctly and the brake voltage is overriding the flasher keeping the lamp on. Since the dirctional lamps work ok with the brakes off and the brake lamps are ok on their own, it's got to be the switch. They're not cheap and if you're careful they can be disassembled and cleaned which may restore the function. If you do try to repair it be warned that there are springs and detent balls inside so watch carefully when you remove the cover and work in an area where you can find anything that flies out.

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'73 Midget (V6)
'59 MGA (I6) under construction
'73 Lotus Europa

"There is a fine line between a hobby and mental illness"

The turnsignal and brake lamp circuits are completely independent, so it's not a turnsignal switch problem. I'm thinking that what may be happening is that there is a problem with the tail lamp grounding, which is causing the stop lamp to ground through the turn signal bulb.

 The tail lamp assembly is grounded through special mounting nuts that have sharp edges designed to cut through the paint. If you car has been repainted recently these nuts may not have done their job.

If the rear lamp assembly does lose it's ground, the stop lamp current can find a path to ground by backfeeding through the turn signal lamp, or side marker lamp filaments, then through the harness to the front lamp ground, which is hard wired. 

It's always worth checking the rear lamps any time there is a strangeness occuring in the TS or stop lamp circuits.

good luck 

 

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Kelvin Dodd
Global Sourcing Engineer
Moss Motors, Ltd.
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Disclaimer: Working on automobiles is inherently dangerous. Moss Motors, Ltd. is not liable for injury or damage due to incorrect installation or use of their products. All products are sold with the understanding that the safe and proper installation and use of the products is the customer’s responsibility. Follow factory workshop manual procedures and instructions, but use current shop safety standards and common sense. Some tasks will require professional advice or services which Moss Motors cannot provide.

This may not be the best place for my posting but what the heck!  Ever since I have owned our 76B roadster the left turn signal has blinked slower than the right one and it is even slower (to the point of stopping and just staying steady) when even more loads (lights, heater fan, brakes) are all on at once.  It does not do so with the right blinker engaged under the same conditions.  I am pretty sure it is a ground problem and just wanted some reassurance before going through the whole system cleaning and checking connections.  After reading the above posting I think I will concentrate on the rear grounds since I did have the B painted in 2007.  I remember having some wierd lighting malfunctions with the blinkers when I put it all together but I finally sorted them out with the exception of the slow left blinker.  I also seem to remember our past two MGBs (71 and 77) acting the same way but it has been too long ago to say for sure.  Any ideas will be most helpful.  Thanks.  

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"I was gonna do it!"

1976 MGB
2010 Boxster

Well, I hate to respond to my own posting but I have experienced further developments.  I checked and cleaned all of the electrical connections on the tail lights, head lights and turn signals and even changed out a few of the bullet receptacles.  After doing so nothing changed.  Then, about a week later I was on the way home from work and my alternator light started flickering.  It continued to flicker and then went solid bright.  I checked and rechecked and cleaned the alternator plug and wiring and it was ok.  Also performed some of the alternator/charging system checks listed in the Moss catalogue and was not getting much, if any, voltage.  I then queried a local European car repairer for advice and he recommended just changing out the alternator and if it didn't do the trick to give him a call for putting it in his shop.  I picked up another alternator under warranty and darn if it didn't fix the problem.  All is well and the left side blinkers are much faster than before but still not quite up to the speed of the right but they do fine.  End result - I think it was a combination of electrical connections and the alternator.  Siddle III (our B) is now happy and enjoying the work commute and an occasional drive.  MG60

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"I was gonna do it!"

1976 MGB
2010 Boxster