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MG MGB Technical - No turn signals?

Well, I got lot's of great help that got me through fixing my clutch problem so I guess I'll swing my newest ailment out for suggestions.
I don't have turn signals. All of the lights involved are fine just no blinkie when I flip the lever. Where should I start? Any help is greatly appreciated.
Thanks,
Scott
S J Kelly

Probably the hazard switch. The turn signal circuit runs thru it. Typically what happens is that the hazard switch is never switched, then finally one day it is (usually by accident). After that, it doesn't want to make good contact in its normal (off) position and your turn signal circuit is broken.
John Hubbard

Thank you John. I guess I'll start there and see how it goes. I can always just use hand signals too until I get it pinned down. Again, thank you.
Scott
S J Kelly

Scott,

Try snapping your hazard switch on and off about 30-40 times. Some times that will clean up the switch contacts and get your turn signals working again.
Dan Masters

I have this problem when other switches are on, heater, window heater ect... Have sought advice but have been told unless I rewire the electrics I have to live with it. The switches get grimmey and dirty, therefore slows the current. Sorry cant help anymore!
Jim

In additon to the hazard switch, which can keep the turn signals from functioning, I have the problem that they don't blink unless the engine is revved enough to bring the system voltage up. If the car is idling or off, they don't blink. Probably replacing the blinker would fix this.
John Hubbard

Scott,

If the lights come on but don't blink, a quick and dirty "fix" is to replace your stock flasher with a type 552 from your local auto parts store (around $2-$3). This is NOT a fix, but it will bypass the symptoms until you can get around to a real cure.

As Jim said, the ony cure is to go through all the wiring involved and clean/replace all connections, including the turn signal and hazard switches.

The stock flasher is current sensitive, so any bad connections in the wiring all the way from the battery to the turn signal lamp grounds will reduce the current. In your case, the current is reduced enough that the flasher no longer will flash, but just stays on.

As John says, revving the engine causes the alternator voltage output to increase, causing an increase in the current, making the flasher work again.

Download the wiring diagrams at http://www.advanceautowire.com/mgb.pdf and you can see how the wiring is routed and where you need to work to clean up the connesctions.
Dan Masters

Replacing a flasher unit where they only flash when the engine revs may well fix it, only for them to apparently 'fail' again a few weeks later. This is because new units tend to be less sensitive originally, then burn in and stop flashing on lower voltage.

As Dan says the 552 is a quick and dirty fix, it doesn't give any indication of bulb failure and so is a safety hazard. Also be aware that it probably only lights the lamps about 1 second or so after you move the switch, instead of lighting the lamps instantly as it should. Judging by how many people turn the wheel *before* they start flashing others around them need *more* advance warning of an intention to change lanes, not less. But I'm sure none of us do that ...

Another alternative, permanent if you must, is a modern 3-wire turn flasher (the 3rd wire goues to ground) which *does* give bulb failure indication by flashing at double-speed. But I'd rather find and fix the real problem of bad connections as these will be causing dim bulbs with *any* of the units.

If you bypass the turn flasher and measure the voltage through brown, white, green, light-green/brown, turn switch, green/red and green/white circuits, bulb holders and grounds you can see voltage differences between adjacent points which will be due to bad connections. As well as the hazard flasher switch affecting both sides equally the ground for the front lights on rubber bumper cars is wired and common to both sides, as well as the headlights. The grounds for the fronts on chrome bumper cars and the rears on all cars is through the mechanical fixings and so is a cause of lighting but non-flashing on one side only.
Paul Hunt

This thread was discussed between 01/05/2005 and 08/05/2005

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