'92 Chevy pickup interior LED bulb question (Page 1/2)
williegoat MAY 23, 04:00 PM
I swapped out the interior bulbs in my '92 K2500 for LEDs so that I don't use so much battery power with the doors opened. Two of the bulbs are 1156 replacements and the dome (overhead) light is a 211-2 type.

When I put in the LED dome bulb, it works as it should with the doors open, but continues to glow very dimly with the doors shut. I put my meter on the light fixture and found about 6 volts at .01 microamps. I know thats not much, but it is enough to barely light the LEDs. Do I have a problem somewhere? Maybe a bad ground?

I put my ohm meter across the LED bulb and it shows open, while the standard incandescent bulb shows about 1 ohm.


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2.5 MAY 23, 05:12 PM
Id say yes there is a problem, I'm not sure what. Ever get a battery drain?
williegoat MAY 23, 05:19 PM

quote
Originally posted by 2.5:

Ever get a battery drain?


No. Often the pickup will sit for well over a week, but always starts.
2.5 MAY 23, 05:26 PM
Does it beg the question, if the volts are sitting there, not being used by an incandescent that they cant light up, do they not drain the battery.... but a low power LED that actually lights up will?



I dig science

[This message has been edited by 2.5 (edited 05-23-2018).]

2.5 MAY 23, 05:27 PM
Have you changed other bulbs to LED? maybe there is a sort of conflict somewhere for lack of a better word.
williegoat MAY 23, 05:43 PM

quote
Originally posted by 2.5:

Does it beg the question, if the volts are sitting there, not being used by an incandescent that they cant light up, do they not drain the battery.... but a low power LED that actually lights up will?



I dig science



I would think that the very low resistance (essentially a short) of the incandescent bulb would drain the battery faster than the (almost) open LED. I think that the very low (.01 microamp) current just drains so slowly that it would take weeks to make a difference. But there should be no voltage there when the doors are shut. I would have never even known about it if I hadn't tried to install the LED.

Actually, I'm kind of surprised that such a low current will light the LEDs.

[This message has been edited by williegoat (edited 05-23-2018).]

LitebulbwithaFiero MAY 23, 05:49 PM
Seems a common problem cured by a resistor
https://youtu.be/d1o6WDvA8F0

[This message has been edited by LitebulbwithaFiero (edited 05-23-2018).]

williegoat MAY 23, 05:50 PM

quote
Originally posted by 2.5:

Have you changed other bulbs to LED? maybe there is a sort of conflict somewhere for lack of a better word.


The only bulbs I have changed to LED are the three interior lights mentioned in my first post and the one under the hood that lights when I open it. The purpose was to be able to leave the doors or hood open without worrying about battery drain. LEDs use much less current than conventional bulbs.
williegoat MAY 23, 05:58 PM

quote
Originally posted by LitebulbwithaFiero:

Seems a common problem cured by a resistor
https://youtu.be/d1o6WDvA8F0



Thank you very much! Now I can change that appointment from the psychiatrist to the bartender.

I have LEDs in three motorcycles and have never had this problem, but of course I never leave the doors open on the motorcycles.

[This message has been edited by williegoat (edited 05-23-2018).]

theogre MAY 23, 07:28 PM
Yes, LEDs will light for low volts that normal bulbs doesn't even begin to glow.

2 possible items...
If only switches are used for on/off then switches can be going bad or dirty.
If BCM etc is controlling them then may use transistors/MOSFET and leak some volts often as part of monitoring for bad bulbs... the famous "CAN BUS errors." The resistor here likely does same as LED saying doesn't cause the can bus problems.

Just read lighting circuits in haynes etc books. First issue should be fix not a band-aid to hind. Second is annoying but isn't a problem to the car in most cases.

0.01ma added to whatever ECM/PCM and Radio standby power will drain the battery but takes weeks at normal temps. If parked for winter then anything draining the battery can make battery to freeze very easy. Freezing battery will kill then even if load didn't drain it more then 1-2 volt low.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)


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