Yet another Indicator Flasher question...?

[geoberni]

Hi All
So, my Series II has the original Indicator set up where the Flasher operates a Lucas Relay to operate the Indicators.
The only difference is that the combined rear Stop/Indicator function has been removed, with the brake lights now fed directly from the Pressure switch and the rear indicators going to separate lamps at the rear. So basically the 'standard' modification of the system.

I've got LED Lamps fitted, which the Lucas FSB105 Flasher has absolutely no problems with.
This week I brought a spare flasher which is supposedly a compatible unit, but having slaved it in to make sure it worked, it simply doesn't like the lower current consumption of the LEDs and flashes wildly as though a lamp had blown.
Have I just been lucky that the Lucas FSB105 doesn't mind having the lower wattage LEDs in the circuit ?

Has anyone else experienced problems along these lines?

[palacebear]

I know it's a bit of a pain, but can you temporarily fit standard non-LED bulbs and see how your new flasher unit performs? Presumably would rule out the new unit being faulty.

[StillGotMy1stCar]

As far as I know the SFB105 is a thermal type flasher unit so shouldn’t work with LED bulbs unless the bulb is the type that has an additional low value resistance added to increase the current to that of a conventional bulb.
Could be just luck with the other flasher unit or it has been opened and had electronic internals fitted.
I think you need an electronic flasher unit compatible with LEDs, or high current LEDs.
Regards John

[geoberni]

Hi
I've managed to find a solitary centre connection lamp and put that in one side and it greatly improves the flash rate.
So it looks like the spare I've just brought is just not up to the capabilities of the Lucas Unit.
The new one can only cope with the higher current draw of filament lamps, not the lower current of the LEDs.

When I originally fitted the LEDs I was surprised they worked OK, Perhaps I'm just lucky with the Lucas Unit I have now.

I've complained to the Seller on ebay and they're sending me another so I'll see if that's any better.
Far as I'm concerned, the Lucas FSB105 works so the compatible should too.

StillGotMy1stCar

Basically I'd agree, the Lucas is a thermal, but its worked fine.
I was the one that replaced all the lamps with LEDs just to see if they would work (at the time I had no idea what the internals were of this strange relay configuration, but I've since found a diagram).
I suspect the Lucas is just a better made Unit and these ones on ebay are not so forgiving in their tolerances.