I've replaced my CEL in the Charger with an LED to go with the knock indicator in my new cal. It now has a faint glow at all times. Is this normal?
It still lights up briefly when turning the key on like it should.
All other dash lights work as they should.
I don't believe it is knock detect as it still glows with the engine off.
Mine glows with the key on also.
Same on my car. I think it's a poor quality LED bulb. I investigated on mine one evening, and one of the 4 LED's was staying lit at all times.
I tried a few different bulbs tonight with no change.
This may or may not have anything to do with LED's but here goes. In my house I have three LED bulbs with all the rest beingLCD. When the power went out all the LED's stayed lit, it kinda freaked me out. I even took a voltage tester to see if there was power there, there was no power in outlet. The power came on four hours later and the LED's were still lit. I have asked various people and have learned LED's have capacitors and they store electricity.
Jim
P.S. If I unplugged or turned the switch off the LED would go off. It has to be a closed circuit. When you turn off ignition you break the circuit !
Last edited by dodgeman87; 09-07-2014 at 01:35 PM. Reason: Further update
Interesting. Thing is, it goes off as soon as the ignition is off. It only glows when the car is running. The glow is so faint you can only just barely see it in the daytime.
Not sure how advanced the computer is but diagnostic current (slight voltage from a pull up resistor to detect an open lamp) will make LED'S glow. A high impedance resistor across the led pins will "drain" the circuit and stop the glow.
Ian Adams Function>Form 1990 shadow scrapped, too rusty:( 1991 Spirit R/T Scrapped, parts sold:( 1989 Turbo Caravan Daily beater with built-[I]ish [/I]engine slowly evolving into weekend turbo beater.
the transistor that grounds the circuit to turn the cel on has some leakage maybe? or the circuitry that applies power to the base of that transistor isnt completely "off".
with a light bulb, noone would ever notice.
Originally Posted by turbovanman
I think it must be something along those lines. Most LEDs run at ~3.3V so it wouldn't take much at all to give it a very faint glow.
The computer is a socketed GLHS LM with a 3-bar chip from Boost Button with the knock detection.
Check the voltage of the led. It should be at 2.8 to 3.3 volts. Usually they only stay lit if the voltage is too high.
I'll check that out if/when the car ever runs again. But should that socket be receiving any voltage at all unless something is triggering the CEL?
Mine does the same thing. It's bright as hell when it's on, so it's not like I'll mistake it. Red LEDs need very little voltage to work. You'll never see this happen with a blue LED since they take typically twice the voltage of a red one to operate.
Jon J.
1989 Daytona ES 2.4L DOHC
2003 Neon SXT - gone but never forgotten
If it ain't broke, fix it 'till it is!
I'm running white bulbs throughout my cluster. Now initially I thought maybe it was really lit up, and only seemed dim because of the red filter, but it lights up bright as hell when I check the codes, so that's not it. The white lights also show plenty bright through the blue and green filters for my high beam and turn signal indicators.
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