Dome light issues 04 prerunner.

Going to try and get a test light today so I may tackle it as well.

 

Okay, here’s what I found with my test light.

TEST LIGHT TO GROUND: Pin 10 black wire at 1H lit the test light in any condition, doors open closed, switch on off, etc. Pin 9 black and white wire at 1H also lit the test light when DOOR was selected at dome light, but not in the ON or OFF positions. Test light would not light on pins 4, 10, or 11 at connector 1L.

TEST LIGHT TO POWER: pins 4, 10, and 11 lit the light with doors open, and each respectively turned off with each door closed. Light did not come on for pin 9 black and white wire at 1H.

Sooooooooo…

Body ECU shot? If so what are my options?

 

I've seen a few posts about a resistor being fried on the Body ECU when using LEDs or shorting the contacts between DOOR and constant 12v. They took the circuit board out and did a visual inspection to find the burnt one and after removing it and soldering on a new one the lights worked again. Tricky part is getting the right value since the PCB design isn't available online - even harder if it physically burned making the color codes on it unreadable. This will be my weekend project coming up because some fool went messing with the map light and accidentally touched the two wires thereby releasing the magic smoke .
If soldering doesn't sound fun you could find a replacement body ecu on ebay or junkyard, but they have to be an exact match (power windows? double cab? power mirrors?) that kind of thing. Worst case you just live without the dome light for the next 20 years until the truck dies.

 

Not an option. My OCD forbids it, it would drive me mad lol. Guess I’m pulling the ECU next weekend!

 

Let us know if you find it, and if it fixes your problem. Better yet, pics of the board and which resistor it was. I will do the same when I do mine.

 

How would you test the board for a fault if there is no visible signs of a blown resistor, hypothetically? If there is one that is clearly a melted mess, that’s pretty easy assuming you can still read the color code. But in the event that there’s not, I’m not familiar with the process of troubleshooting a board. Thanks!

 

Did you swap to a new LED bulb because the previous one stopped working, or just to make a change?

 

The 5 year old one was starting to flicker and not come on at full brightness. Figured the bulb was going bad but maybe it was the ECU?

 

So if you know the pin the signal is supposed to be coming from you might be able to follow the trace from the plastic wire connector (I think it's pin 12 if I'm reading that diagram correctly) back to where it originates from - ideally back to the bad resistor. My board might (and probably will) be different from yours since mine is a 2002 and they most likely added some things to your board that I don't have. Once you arrive at the suspect resistor you can test it with a multimeter on the resistance setting. If it checks out then maybe you followed the wrong trace or the issue lies deeper - if it's the microcontroller you're SOL and it's off to eBay. In which case I'd probably just give up lol. This goes without saying, but do this with the battery unplugged!!! Don't want to short something else out while you're poking around in there.
I'm in no way an electrician, this is just the thought process I would take when doing this.
Someone correct me if I'm wrong.

 

I had the flickering happen with an LED bulb from a set I got from Jumper's LEDs here on the forum. It worked fine for over a year, then began to flicker. I swore it must be some electrical issue with the fixture or a switch, but he sent me a replacement bulb, no issues since.

 

Wish I could say that was it, but it ain’t. Tried two other leds, and the original halogen, all of which worked in the map lights.

 

Update: Took the front cover off the box and it's definitely blown. Looking at another thread, someone had the same resistor blow - apparently a 100 ohm 1 watt resistor. Here's the link to it: Really long shot on dome light issue | Tacoma World. I'll have to order some on Amazon and report back when I get it installed. Kind of dreading it because there's like 12 or 13 connectors on the back side that all have to be unplugged before you can remove the circuit board. May be a while before I do this though as I'm getting the truck painted and will likely be at the shop for a few weeks. Here's a picture of mine: as you can see the labeling is completely illegible, so I'm doing this on the assumption the other thread was correct.

FYI to take off the cover you have to remove the bottom portion of the dash trim. There's two bolts that hold the box on - remove them so you can slide the box over a bit. There's 4 clips that hold the front cover on. Use a flat head or plastic spudger tool and pry each clip back to pop each corner off. Then it should just fall off. Chances are yours is blown too.

 

So did you come to that conclusion after testing with a multimeter? Because I don’t see anything abnormal with that resistor, unless I’m looking at that wrong thing. Also maybe I just don’t know what I’m looking at, was expecting to see a brown and melted resistor. Either, way, sounds like progress! I’ll be pulling mine out either tomorrow or Monday.

 

Anyone have a link on Amazon for the door switches for a 06 Tacoma? Mine quit working awhile ago....I blamed my wife after she drove it!

 

Yeah it's the one that the black tool is pointing at (on the left). That white section in the middle is damage from heat - it would have all been one uniform color but turned white when it failed. If you take yours apart and it's not blown could you still take a picture? Looking online has led me to believe that it might not be the same value resistor as I thought it was. (somebody else said it was 0.33 ohm in another post so that's why I'm hesitant now). Worst case my neighbor has an '01 Tacoma and I can ask him if I can look at the value on his.

 

Will do!

 

Keep us posted, this seems like the furthest anyone has gotten to fixing this issue. The thing that has me curious, is wether it just died from old age, or if I put in the LED the wrong direction? The bulbs I have include a built in resistor, but in order to work it has to go in the right way. Im thing it’s entirely possible that I put it in wrong on accident

 

Blame it on your wife, it works for me! (In my own mind anyway)

 

Lol, I’m not brave enough to try and pull that off.

 

Just curious, is your issue with all the doors or just one of them?