OK Numpty question time

[Highlander]

I have decided to go with LED’s for my warning lights on my dash and have been told that I need to put a power resistor on the ignition/battery warning light and on the oil pressure one. Would it be fair to say that I should be putting one on all of the warning lights and if so what ones do you recommend?

Thanks.

Paul.

[mylesdw]

If you are buying 12V LEDs for automotive use they will already contain the series resistor and you can use them as is.

If you are using 'bare' LEDs (electronic component) you will need to have a 0.25A 1 kΩ in series with each. If your chosen LEDs seem a bit dim with this, lower the resistor value slightly, say 800Ω.

Remember that unlike bulbs, LEDs have polarity - they won't work at all if you connect them the wrong way round.

The charging light might need extra attention, it depends whether the 20mA through the LED is enough to start the alternator.

[Highlander]

Hi Myles,

Thanks for the reply. I am using the chrome bezel ones from car builder solutions here in the UK. I’ll send them an email to make sure the have the resistor fitted.

Many thanks.

Paul.

[mylesdw]

They will have the resistor if they are rated 12V.

The simplest way to get the charging light to work would be to keep the original lamp in circuit; tuck it up behind the dash, and put your new LED across it (across the two teminals, again, must be right way round)

[Bence]

Hi Paul,

PM me, you do need a resistor to make these work as I used exactly the same items. I’ll send you full wiring diagram on email.

Regards

[Bence]

Clear your inbox Paul, cannot reply to PM. Send me your email and I’ll drop you wiring diagram.

Cheers, Bence

[Highlander]

Cleared and pm sent with my email address.

[Mike424u]

Great post guys, Just solved my battery warning light problem, which use to work until I changed it for the car builders LED type.
Then it just stayed on all the time.
Drove me nuts trying to work out why, then I found your post, which makes total sense on, no current to excite the alternator on start up.
Refitted the old type 12v lamp with the new LED and hey presto its back working as it should, just tied the old 12v lamp up out of the way.
Many thanks
Mike

[Russhowell]

Brilliant thread. Buying a cheap bulb to do the same and tuck it up out the way,
Thank you
Russ

[alunwill]

In line diode, never had a problem