About two weeks ago, my turn signals blinked really fast and very dim. So I replaced the flasher with the one from the emergency lights and that fixed the problem. Ordered a new flasher (EFL552) online and used that for the emergency lights. Now, two days later, the emergency lights have develop the exact same problems as my turn signals earlier. So blinking fast and very dim.

So what could be causing the flashers to fail?

Not a broken flasher, more likely a short somewhere.
Take out and check all the signal/side marker bulbs and sockets one by one.

Ogre will probably post his link on "sneak path" to check.
http://web.archive.org/web/...rocave/sneakpath.htm


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[This message has been edited by fierosound (edited 06-17-2020).]

Sneak Path is mainly iffy/bad grounds anywhere.
Like Often for turn/brake lights is front, back or both bulbs w/ iffy connection w/ ground in the sockets.
Most times this cause no or slow blinking.
Most times 1 or more bulbs light Both filaments when only 1 should be on. Just pop the sockets out to look at the bulbs. (Front turn/park sockets twist and pull out from rear but need HL up to get access.)

Fast blinking w/ old cars is often a Short somewhere. Thermal Flasher blink faster as load is at max bulb count or higher then design spec.
Can be anywhere but does it happen for both sides?
If true should reduce the short to common areas...
Examples:
Flash can to column switch wiring.
Column switch is bad or crap in it shorting out.

Unplug C500 and see if still fast blinks. it shouldn't blink at all because too low amps to blink even w/ many new "solid state" flashers.
Unplug C100 to front and try again. (low & inboard of brake MC & booster) Leave C500 unplug. If still fast blinks the short is in cabin wiring.

Dash bulbs, their sockets, and dash "Board" on back of gauge set can short out.
LED "bulbs" can short internally if you have "upgraded" to them.
But both of these only short one side most times.

Note: Often harder to impossible to find thermal flasher in many stores now. Flasher Makers have stopped making most numbers and new "electronic" replacement handle 2 to 20 standard bulbs.
Fiero and most cars has 2 numbers for flashers from the car factory because turn light less bulbs then hazard does. Now you often only need 1 number to replace them.

Could be old flashers died but need to check for shorts and iffy grounds in sneak path page.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Cliff, Do you have LED's in the turn signals. If so, you may need ballast resistors to get the flasher to work correctly. Alternatively, you can try the non-load sensitive electronic flashers if you have LEDs.

If you don't have LEDs, try the flashers from NARVA. I think you can find them in Europe. They are more expensive than the TRIDONs in Australia but I've had good experience with them. Also, When you replace the flasher, be mindful of where it's mounted. Until I relocated them, I used to catch the flasher with a shoe or shoelace getting out of the car. (Yeah, I know it's hard to believe but at my age, I kinda have to roll out of the car or pivot in the seat to get my arthritic knees out.) I messed up a couple of cheap flashers until I changed to the more expensive NARVA units and relocated the mounting point.

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Mike in Sydney

Perhaps I needed to clarify that my turn signals work perfectly. If I switch the flashers, then turn signals don't work but emergency lights do work. So it's definitely the flasher that's broken.

My bad. Try the flashers from NARVA. I think you can find them in Europe. I've had good experience with them. When you replace the flasher, be mindful of where it's mounted.

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Mike in Sydney