Flasher unit

[Gmg31]

I've had three flasher units in my car this week and just cannot get every component to work.  Eventually got the indicators working but last issue is the dash board light. Although it works when powered independently I cannot get it to flash.  Wiring diagrams are useless and I'm not certain the flasher units work properly.  I'm 99% certain I know what I'm doing but Can anyone please advise which wire goes to each terminal (3wire unit) just so I can eliminate user error.

[jbcollier]

http://www.tridon.com.au/products/Tridon/35/478/flashers-and-relays/104171/flasher-relays-electro-mechanical/1770/HD13

click on the wiring diagram.

[EuropaTC]

Electrics, doncha just love 'em ?   

This is the wiring diagram for a 3 connector flasher unit as used on my Elan which should help as the terminals are clearly marked.  I know you're on a new build so everything should be clean and tight, but I'd still go around and check earthing wires to the lights/speedo/etc. I can't recall if the flasher unit itself is earthed without going and looking at the car but as it's bolted to the steering column I suspect it is, although whether it needs to be I don't know without more head scratching.....

The other thing I suppose is the rating of the flasher unit - how much wattage it needs to click into action. Are you using a modern design unit or an olde worlde type ?

Brian

[BDA]

The wattage rating is an indication of how fast it will blink under the same load but I'm not sure which way it goes. I presume the higher the wattage the slower the blink. If you are using LEDs, you will need to use an electronic flasher. Unfortunately, they have a very faint clicking sound.

[4129R]

When bulbs blow, it flashes faster, so I deduce the higher the load, the slower the cycle.

[Stuleslie]

Hi Gmg31, I assume you have a British wired car and if you can see the dash light wiring colours they should be green/white and green/red. If so, these two wires are connected between the right and left indicator circuits. I think this is a rare setup but how it works is that the light relies on one side lighting on while the other side acts as a leak to earth. So you should have a two pin flasher fed from the fuse then onto the indicator switch which in turn connects to either side indicators. With a three wire flasher the third pin to the dash light will assume the other side of it is connected to earth for it to work properly. Another reason the dash light will not work with a hazard warning switch is because both side indicators will be lighting at the same time and an LED won't work either.
With a two pin flasher the more lights the faster it will flash as you are heating up a bimetallic strip quicker to switch off and if you loose a lamp the flasher will slow or stop on altogether. With modern three pin flashers they can often speed up when a lamp goes out to warn the driver that there is a problem.
Stu

[Gmg31]

I feel a lot better now that so many people have different views and experiences and the two wiring diagrams are different. I had forgotten that LED bulbs might make a difference.  Mine is a three wire flasher unit. 1 wire is the ign live supply. 1 goes to the the indicator stalk 1 goes to dash board light.  The unit has to be earthed and I think that was my first mistake, I soldered a wire to the bracket on the end and I think the heat might have damaged it.  I've order yet another one and will have another go next week. Thanks all for your help.

[buzzer]

If you flasher unit is the bimetal type (i.e. the original type) LED bulbs will not draw enough current. If you are using an electronic flasher unit you may have to rewire the single dash indicator light. As Stu says this indicator bulb uses the the other side that is not flashing to earth the indicator through. This messes up LED bulbs as they trigger on much lower voltage and pull much less current. In this case all your indicators will flash. I used LEDs and electronic  unit and wired in diodes for the single dash light to drive the dash bulb. so both sides were wired in to the bulb via a diode and the other side of the bulb was earthed. works a treat.

[Gmg31]

Turns out that both of the circuit diagrams above are correct just slightly different. The key mistake was that the flasher unit does not need to be earthed. New unit arrived today and worked first time. Surprisingly my LED  bulbs work fine.

Thanks again for all of your help and advice, inching ever closer

[buzzer]

Good progress, is the flasher unit electronic or the old bimetal-strip type? Am surprised if bimetal-strip type would drive LED bulbs correctly, but ready to be corrected if works ok.

[Gmg31]

Yes its an original Lucas bi metal strip unit, I only have 2 LED bulbs out of the 6 and they all seem to work well.  I fitted shallow smoked lenses to mine and so I had to fit very shallow yellow LEDs.  If I'm honest I'm not sure it will pass the MOT test with those but I've kept the original lenses just in case.

[EuropaTC]

The smoked lenses with coloured bulbs was a common mod on S1 Elises when they were around and I don't recall anyone having problems. I even think smoked side indicators (the small ones that go down the sides of the front wings)  were an option on one Vauxhall car because even Halfords sold those. 

As long as the LED gives a yellow light I think you'll be fine.

Brian