Dash LED's

[Brent69]

I just installed LED's in my dash cluster recently restored by Auto Instruments.  At first, the LED's in the dash didn't come on, but after jiggling the dimmer switch a bit, I got them to come on.  If I just barely move the dimmer wheel, they'll go off.  I know that you lose the ability to dim the dash lights when you switch to LED's, but shouldn't the LED's come on full regardless of where the dimmer wheel is?

I never installed standard bulbs in the cluster since it's been restored so I don't know how it would behave with regular bulbs.

I don't want to pack up the cluster and send it back if there is nothing wrong with it, but I'm really starting to think that there is a problem with the dimmer wheel.  I already had to send the cluster back once because the indicator needles and clock face for the tic-tac-tach came off during shipping.  Now possibly a problem with the dimmer wheel..?

What do you guys think?

[OttawaCharger]

you can't dim the LED lights like you could the old incandescent ones. The headlight switch in your dash is a potentiometer, which varies the resistance to dim your dash lights. The old incandescent bulbs had a resistance of a few ohms. The headlight switch resistance adjustment is somewhere on the order of from 0 ohms to maybe 100 ohms or so, and then it goes open circuit at the end of its adjustment. The newer LED lamps draw maybe 10 milliamperes (0.01 amperes). They will have resistors built into them to limit the current to this level when supplied with 12 volts. Since your headlight switch dimmer will only vary by 100 ohms, your total resistance in series with the LED lamp will now vary between 1000 ohms and 1100 ohms, and you won't be able to dim the LED.

So in short, your dimmer wheel is probably fine.

[A383Wing]

I put LED's in my 94 Dakota dash..in place of the #194 bulbs...they dim just fine

Bryan

[Brent69]

So OttawaCharger, you think it's just a matter of finding the sweet-spot on the pot where the dash LED's light up and leaving it there?

[OttawaCharger]

So OttawaCharger, you think it's just a matter of finding the sweet-spot on the pot where the dash LED's light up and leaving it there?

I believe so - yes.  You might have a couple sweet spots real close together but generally it's an all or nothing situation.

Bryan - more modern cars have gotten away from using current control for dimming as voltage control is more efficient.  LEDs work much better with this type of dimmer.  Your Dakota would've fallen under this I believe.

[2Gunz]

You should be able to dim them.

The dimming curve of LED's is much different than normal bulbs however.

[Brent69]

They just seem real sensitive to any change in the wheel.  That's sort of what makes me think there is a problem with the wheel, even though it's just been reconditioned.  I'll mess with it some more this weekend and see how it goes.

[Brent69]

Took the dimmer switch out and cleaned it really well.  Put it back in and the LED's do dim now.  Works much better.  I got all interior lights switched to LED's except the gear selector light on the floor console.  For some reason a normal bulb works in there, but could not get an LED to.