9 replies to this topic

[Michaelo85]

I purchased some 12v LED bulbs for my Rover 2 clock dash. All the other bulbs light light fine backlight,oil pressure,battery. But the two indicators/hazards won't come on.

I've tryed swapping the polarity about and tested with mutimeter bouncing between 0v 9v.(might be higher not sure the refresh rate on my mutimeter is)
Are the indicated dash light a lower voltage? Or they not working because LED are diodes? Put the old standard type bulbs back in works fine.. ? Any ideas why the led's arnt working?

[gazza82]

They might need wiring diferently. Car Builder website has diagrams.

LEDs are polarity sensitive too so the might be reversed?

[Midas Mk1]

Make sure you don't use an led for the battery charging light

[Michaelo85]

Why not Midas? I have stuck a led one in there its working.

[Midas Mk1]

Your charging system relies on the filament bulb to give a certain resistance in the circuit to allow the alternator to charge, with an led it won't charge properly. Can be solved by adding a resistor, loads of threads on tmf about it :)

[tiger99]

But even so, please don't do it! There are many pitfalls, especially as it can see reverse voltage in certain conditions, and LEDs will fail if subjected to a reverse voltage significantly above their rating, which is usually only about 5 volts. A bulb, when cold, has a much lower resistance than when hot, maybe a quarter or less of its nominal, which can give a nice healthy injection of current to get the alternator started. A LED with plain ordinary resistor can't do that, and some alternators will not start up correctly.

 

That could be why the others don't work, they could already have been destroyed by reverse voltage.

[Albino_Hedgehog]

Have you got s electronic flasher unit? Having a standard one can cause issues with LEDs!

I have LEDs in all my exterior lights so have ran into a few issues occasionally!

[Michaelo85]

I've put back the original bulbs in the indicators and battery light.
I did add a few resistors to match the resistance of the incandescent bulbs but they they kept burning out. So I'll just keep them standard. Yeah I've got a electronic flasher unit. I believe it's voltage stabiliser that not making dash led's flash.

[Michaelo85]

I've put back the original bulbs in the indicators and battery light.
I did add a few resistors to match the resistance of the incandescent bulbs but they they kept burning out. So I'll just keep them standard. Yeah I've got a electronic flasher unit. I believe it's voltage stabiliser that not making dash led's flash.

[Icey]

I believe it's voltage stabiliser that not making dash led's flash.

The voltage stabiliser isn't connected to the indicators, only the fuel and temp. gauge.

I would need to check the diagram but I suspect the LEDs themselves are the problem, can't give a reason just a hunch at the moment.

Edited by Icey, 19 September 2016 - 12:18 AM.