Dashlight Dimmer Not Working With Leds.

[B0oStEr]

I know my dashlight dimmer used to work but i haven't had a need to adjust it since I bought the car.

Now I've fitted LED bulbs to the dashlights and I tried to turn them down but the dimmer doesn't work anymore.

It's either full bright or off.

The aftermarket boost gauge that used to dim doesn't dim either.

I don't see how fitting the LEDs could cause this but I have only noticed it after fitting them.

[Fixxxer]

I think another person was having trouble with this. Talk with Dan666. I think the LEDs have a narrow power band type thing, and you're dimmer switch doesn't allow a small enough change to dim the LEDs before they go off.

Fixxxer

[wraith_skyline]

Thats pretty much right, being diodes they have a certain voltage when they are on and once that is hit they are on, thats it so the dimmer wont work at all, mybe you could put a smoked cover on them to dull them down

[tek_01]

sorry for hijacking but does an r33 gtst have a light dimmer? havent seen one but havent really looked hard enough

[Kinks]

standard, no. a lot of them had dimmers fitted for compliance though.

me, I put brighter globes in. the standard dash is dimmed from the factory

LEDs have a fixed voltage across them, but more than that they don't scale linearly with current. If you put 20mA through one it's not twice as bright as if you put 10mA through one. Unlike a regular bulb which drops off in brightness very quickly if you try and dim it.

[B0oStEr]

Thats pretty much right, being diodes they have a certain voltage when they are on and once that is hit they are on, thats it so the dimmer wont work at all, mybe you could put a smoked cover on them to dull them down

Actually this isn't the case.

I have solved this problem by changing the original variable resistor (0-7.5ohm) with 500mA variable resistor from Dick Smith (0-500 ohm) and the LEDs dim progressively from full bright right down until they go out.

In fact it works so well my aftermarket boost gauge also dims at the same level which surprised me somewhat.

[(B1) MR_fanny]

my led dash works fine with my dimmer. its a factory fitted dimmer to not the poxy knob one that you get durrind compliancing.

[jeffworld2]

anyone know why the r33 dash keeps blowing leds? ive tried a few different sets which are for the gtst's and they all seem to burn. first the one at 80-180km/h then the rest. I dont beleive they are loose or anything im trying to work out whats happening