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MG MGA - Flasher relay woes! Need help!

Well, I thought I had it fixed, but I am now on my 6th signal flasher ('60 MGA)....All have burned out in less than a week , after working....
I had added a voltmeter to the dash, so I could tell what the car's generator was putting out, and it runs at about 12.5 volts with the lights on, and around 13 with the lights off....Not enough voltage to fry a flasher....
When a new flasher is installed , it will work perfectly for a few drives, and then just quit....
I have tried three different brands of flashers, including the high-priced one , sold by Moss, but they all fail....They short internally.
Running lights and headlights are fine, as are the wipers, and other circuits....
With only two fuses in the car, with both good, I just don't see what is burning out the flashers.....
So positive suggestions are needed.
Edward Wesson 60MGA

Bulb wattage correct?
Were they all the same brand / model?
Can you check the amperage vs flasher rated?
Does it get too hot?
Art Pearse

Maybe you have an intermittent short in the flasher circuit. I think I would short out the flasher with an ammeter and check the current in both turn directions. Should be 3.5A with normal bulbs? Do you have an alternator not a dynamo? Maybe it's generating high voltage spikes (know nothing about this)

If you've blown six flashers try opening one up and doing a bit of failure analysis. Do the flashers fail when turning one particular direction? I think you need more clues..........................Mike
m.j. moore

PS To reduce your consumption of flashers put a 5 amp fuse in series until you've solved the problem. Cheaper to replace a fuse!
m.j. moore

I had this problem and I think it's just because the units that are currently supplied are of a very poor quality. I got a heavy duty unit from Vehicle Wiring Products here in UK - product code RFL5. This is a 4 terminal unit which is wired as follows -
Terminal C light green wire to dash lamp
31 black earth
49 dark green supply
49A green/brown switch
Hope this helps

p parmenter

Stop buying replacement units from Moss, etc. and go down the local breakers yard and pull an electronic unit with 3 terminals out of any modern motor, they wire in to the car easily with just one extra wire to ground.
Chris at Octarine Services

I had same problem. Barney suggested buying one from local parts store. (common item). Problem solved. I put new flasher inards in old canister to look original.
Good Luck

Just a few additional notes....
I did take one of the flashers apart, and there was no visible damage....That means to me , that either the transistor failed, or the diode failed...
I thought at first that the problem was the "Lucas" style flasher that came with the car, when I bought it in the Spring...I didn't want to send off just for a flasher, so I went to the local "Parts City", who had one that said it was for MG's....It was the first one to quit...So I went to the NAPA store, and got another, and it quit....So I went back to Parts City...etc...
Anyway, the last one, was the high-priced Moss unit, made in China (as most are), and it quit within a week.
What is weird, is that I set the regulator down, because I thought it might be sending too much voltage to the flasher...With my new, dash mounted , gauge (a high quality one), I'm only getting between 12.2 and 13.5 volts, depending on what's running.
No dead short can send more than that to the flasher, because that's all the voltage coming out of the regulator....
These flashers are not directly grounded, and have only three wires...power, indicator, and switch...
When first tested, 12v is only on one leg....When it burns out, 12v is available on two legs.
Someone suggested going to a three wire flasher used on the 18 wheeler "big rigs"...But this will only treat the symptom not the cause...
More help please.
Edward Wesson 60MGA

I had the same problem when I fitted a new Moss flasher unit. I went threw 2 flasher units. Then I remembered I had an old wiring loom in the garage. I removed the 50 some odd years old unit and placed it in my car. Works perfectly now!

Moss units being supplied are definately junk! They are a great supplier but I hate being used as their Experimental lab rat for quality control. Still its hard to be good at everything and overall they are the best for suppling parts for a car thats running 40 years after its throw away time!
Steven Devine

Went to Loew's yesterday, and bought a DC ammeter....
I'm going to see if I can find out how much amperage is going through the flasher....I'm not sure how I can do this with the bulbs not working, but It's a start.
I am also going to find out what the correct turn-signal-bulb replacement numbers are...I want the numbers that I can buy locally...
I'm then going to replace all four bulbs, and the bad flasher....
Finally, I'm going to make sure all four sockets show a good ground.
Edward Wesson 60MGA

Problem solved! See my thread on bulb numbers....
Thanks everyone.
Edward Wesson 60MGA

This thread was discussed between 05/10/2013 and 09/10/2013

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