Dome lights won't turn off!

As far as I know there are switches on each door opening, and when the doors close, they trigger/close the switch. There's also a fuse for these door switches and a fuse for a "dome relay" or "door relay" or something to that effect - I forget the actual wording, but checked the fuses and they're fine.

As far as the head unit, I assume you mean the touch screen? Certainly no obvious way to access any features beyond the audio, but I guess it's possible! Would love to know how.

 

If you are going to put LEDs in. Make sure the power is off. The lights ate polarity sensitive. If they don't work take them out and flip them around. If you try it when the switch is on. You may cause a surge and damage something. Also use quality bulbs. No use cheaping out on a brand new truck. Cheap LEDs are known to have issues.

 

So, something to remember is that LEDs are CURRENT controlled devices, not voltage controlled devices like traditional halogen or incandescent bulbs. Additionally, they are NON-LINEAR devices, meaning that you can't just approximate the current they'll draw by assuming they'll behave like a resistor (like you can with halogen or incandescent). When you hook an LED up to a voltage supply, assuming that the voltage across the LED is high enough for it to turn on, the LED will draw as much current as the supply will provide. So, in the case of your car, if you hook an LED straight up to the battery through a 7amp fuse, it'll blow the fuse cause it'll try and draw more than 7amps. Chances are the LED will also destroy itself in the process.

So, how do we get around this? There are two commonly used ways. The simplest way is to just put a resistor in series with the LED. This will effectively limit the current drawn by the LED, making it act more like an incandescent bulb. However, this is very wasteful. Why bother using an LED if you're going to burn a ton of power off through the resistor. So, the second way to use LEDs in voltage-controlled systems (like your car) is to use a dedicated LED driver. These guys will supply the exact current you want to the LED, and will allow the voltage to swing up and down to make the LED happy. This is the most efficient way to use an LED.

Some LED boards you can buy for cars have current-limiting resistors built into the board so you don't need to worry about having a driver. However, others are intended for use with a driver, so they don't have any resistors on the board. With these boards, you can either use a driver, or you can put a resistor in series with the LEDs so you don't need one (need 1 per strand, don't clump strands through 1 resistor). Again, this is wasteful. If you're going to do this, make sure you have a resistor that is both the correct value and power rating. Remember, resistors can get very hot depending on the amount of power they're dissipating, so be sure they're in a safe place, or better yet, heat-sinked.


All of the above is for people who want to install LEDs in their trucks in the future. Make sure you know if your LED bulb has current-limiting resistors or not. Also, make sure the LED bulb has similar current/voltage characteristics to the halogen/incandescent you're replacing.

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What does it mean for you guys that already installed them, blew a fuse, and now have issues?

Most fuses in cars aren't there to prevent components from being damaged. Most of the time automotive fuses are slow-blow, meaning that high current had to be flowing through them for a few hundred miliseconds or so. This is to prevent wires from becoming so hot they catch fire, or from your battery deciding it wants to create explosive hydrogen gas that'll get trapped under your hood. The fuse blows to prevent CATASTROPHIC failure, but some components could still have been damaged.

My guess? The transistor/solid state relay in your lighting circuit got fried. I don't know the exact circuitry used in Tacos, but if I were designing it it'd be something along the lines of this: tri-position switch either directly controls power to the lights (when in on/off) or allows power to flow to the lights via a computer-controlled transistor or solid-state relay. When in this last mode, the computer will decide if the lights should be off or on depending on doors being opened/closed etc. The computer tells the transistor/solid state relay whether or not the lights should be on. Its the transistor/relay that actually draws power from the battery to power the lights. Hopefully there is an opto-isolator between the computer and the relay, otherwise the computer could have gotten damaged as well. If the computer got damaged, hopefully it's just that particular I/O port and not anything else, otherwise you're in for a world of hurt.

Another thing that could possibly be going on is that the relay needs a certain amount of current flowing through it to operate properly. Some relays take advantage of the power flowing through them to actually operate. If the Taco is using this kind of relay, then it could be possible that the LEDs are drawing so little power that the relay won't work. I know some of you said you put in the old bulb and things still aren't working, so I doubt this is the issue, I'm just including this idea to help others with their troubleshooting.

 

Did you tell them the you put an LED in there? and it blew the fuse? etc.? .
If so, that's why they're talking $80/hour and 'if it turned out not to be under warranty' bullshit. They're saying YOU did it.

I'd double check the door switches.. A long, long time ago, I had an issue related to a faulty switch

 

I assume he must have been honest with them about it for them to say he has to pay. Not to encourage this but try another dealership and don't tell them, see if you get another answer. I would more interested why they couldn't find the problem regardless of a bill or not.

Glad you were honest because if you caused it, they hey your bad, but still why couldn't they figure it out is what interests me the most.

 

I don't know man, a mod as simple as changing a bulb shouldn't cause a short somewhere. I think Toyota should step up and find/fix the issue under warranty.
Gee wiz.. a $35k+ new vehicle should be covered for issues caused by swapping a bulb, regardless of bulb type. Which is exactly what happened. Owner changed bulb, and system shorted out somewhere. Unless it's explicitly stated somewhere, 'WARNING - DO NOT USE LED BULBS AS ANY ELECTRICAL ISSUES WILL NOT BE COVERED UNDER WARRANTY'

 

Oh it would and should be. However I have a very good friend that was a Toyota tech and he even scratched his head for a second when I was talking about this. If I recall he mentioned the whole upper console in a Seinna has a control board and he has seen those fail. Could be the same thing here. That LED light blew something on that board which will result in a new one being required.

However, if you walk in and say I did this incorrectly and something broke, you basically void any agreement to warranty because you did something outside the normal recommended warranty requirements. If you jam a screw driver in and short it out it's basically saying the same thing. Even though a simple bulb is really basic it wasn't a standard item / bulb.

 

I wouldn't write off the door switch as a possibility. Like I said, I had this happen to me right after I had my front windshield tinted. I have not replaced any lights with leds. Lasted a day. At least I hope it was a wet door switch. Otherwise there's something fucky with the board.

 

Do you have a picture of the domelight assembly apart? Haven't had one apart myself but have ran into this issue on other vehicles. Is it A stamped circuit board or a typical computer circuit board

 

Looking at the diagram you could check the yellow wire coming out of the overhead console box. All of the door switches send signal to the body control module which grounds the dome circuit on that yellow wire. If the timer is built into the console box circuit board the yellow wire should be grounded with the doors open and go away when closed.

I should be able to confirm this on Monday.

 

I have been an electronics technician for >35 years. The Dome light is controlled by the Body ECU when in the door mode. What happened is you shorted out the circuit with the LED. The circuit was overloaded ( excessive current ) which blew the fuse. The fuse is a standard automotive fuse which is designed to prevent the wires from burning, it is not there to protect the electronic / electrical devices.

The Only way to protect the Body ECU from an over current is by using an electronics instantanious fuse and even then it is a crap shoot if it will prevent this.

They will probably have to replace the Body ECU to repair your dome light.

For those that say this should not happen and Toyota should fix this. Well there isn't an issue with the truck. It was designed for a standard bulb, when you mod you take the risk...

 

Its on the back side of the interior fuse box. Some models it can be replaced some it comes with the entire fuse block.

 

The same is true for the second generation Dome Light Controls it is controlled by the Body ECU which is where thepinktaco said behind the inside fuse box. I haven't dug into it to see if it is separate from the fuse panel, I feel that it would be.

I have a feeling that what happened is that the LED he was trying to use has a heat sink built into it and it shorted between the hot wire and the body ground. Big power surge...

The switch controls the light in the Off and On positions. That is why the light still works for Off and On. When it is placed to the Door Position it connects the ground side of the lamp to the Body ECU via pin # 7 ( Blue Wire ) on the Body ECU which then switches the ground as needed. That is also how they control to timer and dimming on and off functions for the dome light when it is in the door position. What is most likely is that the switching circuit in the ECU for the Dome Light is now a direct short to ground and that is why it never turns off.

Granted I do not know the exact method of the failure and I am still guessing based on what I have read here...

 

Yep he is saying exactly that.

 

Pretty much yes.

 

I suppose warranties are nice things to have...sometimes.

 

Update on my status. Lights were fixed. The dealer replaced the entire overhead console.The source was caused by a short in the overhead console, but the exact location of the short is unclear.

It is safe to say i will continue to use the standard halogen bulbs.

 

Nice to have closure. However the burning question is did you get warranty or did you pay?

 

Assuming it shorted out the capacitor built into the circuit board.

 

I'm assuming that they covered yours under warranty? Did you tell them about the led? Or did you put the stock bulb back and play dumb?