LED dome light doesn't illuminate when "cold"

First off, yes I bought this bulb from superbrightleds.com. And yes, I added two 1w 100ohm resistors in line in the dome light.

Second, the light works as expected under almost all circumstances except this one. I have searched around and reread a bunch of threads and can't find anyone mentioning this particular issue.

Now the issue. When I open the door after the truck has been sitting for an as yet undetermined length of time it doesn't come on. I can switch it to either "Door" or "On" and it won't light up unless I put the key in and turn to Acc. If I drive around for a bit then turn off the truck, take the key out and open the door, it lights up fine as expected. I can even get out, lock the door, wait a minute or two and open it back up and it lights right up. Let it sit for a while, open door, no light. I have to double check but I'm almost positive the map lights are doing the same thing (same bulbs in them, no resistors added).

Initially I thought it might be the cold weather since it seems to work fine once the truck is warmed up. But then there was a few days where it got up to around 60F and it was still doing it. So I don't think that's it, plus they work fine as soon as the key is turned to acc.

So in summary:
Truck "cold" = dome light doesn't turn on unless key turned to acc.
Truck "warm" = dome light will turn on without a key

Any ideas?

 

THAT TRUCK IS DESTROYED......
GET A CAR INSTEAD

 

Buy a standard dome light bulb for 70 cents and be done with it.

 

The end result would be the same, the standard bulbs are practically useless.

 

Hmm as far as I know LEDs aren't affected by extreme cold so you can probably throw that out as for the resistors I think the same thing applies, not affected by the cold. Maybe there is a loose connection that after driving around got bumped so it works again

 

My standard bulb turns on every time, even when it's cold.

 

My LED I bought from superbrightleds.com does too.

 

So I'm curious...what do you think the advantage is of and LED in this application?

 

It's perfectly consistent and has been for a couple months now. That would be way too much of a coincidence.

Let me rephrase that, the standard bulbs suck ass and you can't see shit when they are on.

 

Speaking on my own behalf, the LED bulb seems like it's 100x brighter than the stock festoon bulb.

I can actually see almost every nook and cranny in my cab now at night when the door is open (including in the consoles)

 

Just tested some things out, trucks been sitting for about an hour.

Open door, no light. Map lights don't work either.
Insert key, turn to acc, light comes right on.
Take out key, light stays on.
Close door, lock door. Light goes out.
Unlock door, light comes on.

One thing I did remember is that I have my CB wired into the acc. fuse. Wondering if that's messing it up. I pulled that wire, I'll give it a while and try again.

 

hmm true.... Im not sure what would happen if a resistor would go bad in this situation but maybe check and see if one of the two went bad other than that I really dont know has it been like this since you put the LEDs in or has it just started randomly

 

To each his own. Can I ask you how you installed the resistors? Do you have a pic? Assuming you soldered it, you can often get a cold solder joint if you don't prep the surfaces good. The solder will look good on the outside but won't be electrically sound on the inside.

 

Always been this way, I just put them in. It was the same way with one resistor. Thought maybe that's why everyone says you need two so I added the second but it was still the same.

 

Sounds like a computer issue. The dome circuit should be computer controlled since it is part of a much more elaborate circuit. Sounds as if the computer is timing out after a certain period of time and no longer supplying power to the circuit.

To trouble shoot, start here...

1. Next time you open a door and the light does not turn on, look as the cluster and check if the open door indicator is lit. If not, its a circuit problem or a door pin problem. If it lights up fine with or without the dome light, continue to step 2, if it does not light up, check for faulty or sticking door pins or trouble shoot the circuit.

2. Replace bulb with standard halogen light like oem and test for a week or 2. If problem persists or even just happens once, then it has nothing to do with the light and is an electrical problem. Check circuit and door pins. If the OEM bulb works fine, continue to 3

2. If problem stops with switching out the led with halogen, then put the led back in and they replacing the resistors since they are less than $1. Test again. If problem persists, I recommend trying a new light. Email superbrightleds.com if your under 1 year and they will warranty it. Just say it doesn't light up anymore. If problem persists with a new led, then I'm still betting on a door pin/trigger or electrical issue.

Also make sure your resistors are insulated very well and check for shorts. May I ask why you are using resistors in the first place these are 12v LEDs an should not require any voltage drop. Maybe there is something I don't know about first gens

Its not likely, but possible for temperature to affect the function of a resistor by increasing is resistance if too cold. How are they wired, how well are they insulated, how cold does it get where you are, and where did you get these resistors from and how old are they?

 

Wire tap on the hot wire with a short lead that's soldered to the two resistors, then the other end is another short lead soldered to the two resistors with a ring connector on the ground screw.

I'm pretty certain it's nothing with the resistors though, since I believe if those were bad/not connected well then the light wouldn't work at all without the key turned to acc. which is not the case for me.

 

Ummm... Just for giggles, did you try putting the original bulb back in to see if it works properly?

 

Thanks, I'll try it out. Unfortunately I don't know yet how long it takes to "reset" to not working.

It's possible I don't need the resistors at all. I might have popped in the bulb and the light didn't come on without acc. on so I added the resistor and it worked. Which may have been soon enough that this condition hadn't reset itself.

And yeah, gotta see if I still have one of the original bulbs laying around to swap back in. It's entirely possible this was happening before, the old bulb was giving me issues, but I don't recall it being this consistent. More like it sometimes worked sometimes didn't regardless of the situation.

 

Narrowed it down to between 15-30 minutes before it stops working. Pulled the CB power wire out of the acc fuse and waiting 30 minutes to see what happens.

Oh and ProForce, I have a 1st gen. There's no door indicator. But also to note, when it doesn't work, if I open the door then insert the key and turn to acc. without touching anything else the light comes on so I don't think it's an issue with the door itself.

Don't have any of the old bulbs unfortunately. I don't really think it's a bulb issue either as it works perfectly fine otherwise. I have three of the same one though, two for the maps and one for the dome, so I can swap them around if it comes down to it.

So to add to the steps of what happens:
Open door, no light.
Insert key, turn to acc, light comes on.
Take out key, light stays on.
Close door, light goes out.
Open door, light comes on.
Close door, light goes out.
Wait 30 minutes.
Open door, no light.

 

The first thing I would try now is each of the door switches (on all four doors). Verify that the same thing is happening. This will eliminate the door switches, connectors, and their associated wiring.

Then, I would disconnect power to the battery for a few minutes, then reconnect it. Try again. This would eliminate a brain fart in the body ecu which controls this circuit.

If this doesn't solve the problem, I'd be willing to bet dollars to doughnuts that your LED/resistor circuit is causing a ground problem. The design of much of Toyota's control circuitry is that it is ground activated. For instance, the door switches actually causes a ground that completes the circuit and allows the ecu to power the light. When you start adding LED's with resistors, you start changing the overall circuit resistance and the ground will not work correctly. Weird things start happening when you have ground problems. When I installed my backup camera, it would not power on consistently and the video would be streaky. It was all due to a single ground connection in my tail light. Once fixed, perfect operation. The difference with the acc on is that the light timer is activated, which changes the operation of the ecu somehow. It is hard to exactly know what goes on in the magic box of the ecu, but with everything ruled out... my guess is that if you put a normal bulb back in it will work properly. I'm not saying you can't get this to work properly with an LED or LED/resistor combination, I'm just saying it's not worth the aggravation imo.

If you look below at post 16, you will find Bloo has a similary problem. Hence why I don't put LEDs in any Toyota design circuitry... just custom circuits. It's not worth the problems.