[Jigg007]

So, my class ends at 4:45. I walk out to my car in the parking lot, passing a scratched up 1996 with a flat tire. I think to myself, "well at-least I take good care of my car" Open the door, start the car, and crank the A/C. Before I drive off, something doesnt smell right. Thats when I notice smoke pouring out from under the steering wheel!

I promply GTFO out of my car running around in circles flailing my arms.

First thought: Disconnect the battery, dumbass!

Response to first thought: But theres another battery in the trunk!

Do it anyway! OK!

Then I realize the other day I removed my tool box from my car, leaving only a 10 and 11mm wrench. Leaving me unable to remove the 13mm tension bolts for the battery clamps.

Hastly, I go to find out where the smoke is being generated. With the 10mm wrench I remove the dash so quick you think I do this frequently or something.

Right next to the OBDII connector, is the integration relay that controls the chime and most of the lights. The unit is scalding hot with a nice hole burned though the top. quickly I rip the unit from the car, and being the electronics junkie I am take it apart. (mind you this is all in a parking lot! (which would of made it more interesting if the cops rolled by..))

With the module removed, I had no headlights, so being its over a $200 part from the dealership, I decide to butcher it, Long story short, the two big resistors that burned up are for the dome light to turn on when the door is opened. Needless to say, removing these resistors disables that function, but for $200 I can live with it, and more importantly I have headlights until I visit a scrapyard.

3 hours later, my car and I still smell of burnt circuit boards, arsenic I believe.

 

[The Digital MagE]

why did the resistors burn?

 

[Jigg007]

I am unsure, though I have a few suspicions now that I think about it.

The fuse for this module is listed as "gauge" which calls for a 7.5A fuse, there happens to be a 10A fuse in the socket instead.


Also, about a month ago I was messing around with the dome lights, more specifically the output from the overhead one. I couldn't get any accurate readings so I taped up my splices and forgot about them, maybe they found a cunning way out of the electrical tape hell.

 

[The Digital MagE]

yea - 10 amps is a LOT of current. i wonder why modern cars use so darn much current. perhaps its momentum from the older days...

the roof area is where a lot of condensation goes on - hotter air rising to meet the cool roof metal. so it's likely that your tape got wet - lol - and that caused it to slip off the wires!

the dome light is funny - i replaced the bulb in mine and now it works, sometimes. when it doesn't i just tap it, and it works some more! i think the copper rivet loses contact with the stainless contacts - i've seen that before and there isn't much you can do about it. solder won't work and the plastic will melt.

anyhow, good luck with your repair. i really like the way your dash bulbs look in your picture. my car just runs and drives perfect, and that's all i really care about.

 

[GOT BOOST]

OP,

Do a cross reference on that part number on the box. I suspect it might be the same relay as in the Camrys. In that case you can go to a junk yard and pull one out for pennies on the dollar.

 

[Jigg007]

OP,

Do a cross reference on that part number on the box. I suspect it might be the same relay as in the Camrys. In that case you can go to a junk yard and pull one out for pennies on the dollar.

Yes, I belive anything past a 94 camry to reasonable early 2000s camrys will carry the module, I think the siennias/solaras with the 1MZ engine might also have it, but that may be pushing my luck!

Ill check all my wiring before replacing the module, and when a new module is installed, I hope it does its job, and not burn up. Otherwise I might have a mighty problem on my hands!

It also turns out that the correct fuse was installed. And that the module pulls power from the "gauge (7.5A)" and "panel (5A)" fuse.

 

[The Digital MagE]

there is a short, somewhere. count on it. i'd check the wiring for the dome light...

 

[Chunkywolf]

I could pop open mine if you'd like the resistor values.

 

[Jigg007]

I could pop open mine if you'd like the resistor values.

You would be my hero if you did that.

I was going to ask, but I figured many would not be willing to remove dash panels to open an electronics module. I am thankful that this is not the case.

If you could take a picture of the board, top and bottom, that would be sweet.

 

[Chunkywolf]

There ya go!

 

[Jigg007]

Thanks so much, Chunkywolf!

I think I'll run to Fry's Electronics tomorow and pick up some 1.8Ohm (they look like 2 watt!) resistors and give it a shot.

Im questioning myself if that glass diode (above the large resistors) is poof'd too, or if its singed from the heat/fire. The question is, is it a normal diode, or a zeiner diode (thats a pain, because who knows what breakdown voltage it is)! If it is a zeiner diode, it may very well work with the large mosfet, as a crowbar circuit, and that diode could be what caused the resistors to smoke in a system failure. (but why design to blow resistors instead of a fuse?, ohwell, more thoughts tomorow!)

 

[The Digital MagE]

there are several questions generated by this, the first of which is, why did this not simply blow a fuse?

just as i might ask why i still get cat codes when i have a 3 week old cat, and 3 brand new 02 sensors...

the answer is, quite simply, that these cars are made to MAKE MONEY AFTER THE SALE. in your case, a $200 board. in mine, to EXTORT cubic dollars from me for a toyota cat or to make me miserable, 'cause i know my engine is not running right.

fool me once, shame on you. but twice, shame on ME! i had a 1990 camry - it was great. and so i... FOOL! there will never, ever be another toyota.

i'll jury-rig this one. i'm stuck with it - i could never in a zillion years get anything like what i have invested in it. i can't enjoy it anymore. i hate the go**dam thing! every time i drive it i am waiting for the next ripoff...

 

[Jigg007]

there are several questions generated by this, the first of which is, why did this not simply blow a fuse?

just as i might ask why i still get cat codes when i have a 3 week old cat, and 3 brand new 02 sensors...

the answer is, quite simply, that these cars are made to MAKE MONEY AFTER THE SALE. in your case, a $200 board. in mine, to EXTORT cubic dollars from me for a toyota cat or to make me miserable, 'cause i know my engine is not running right.

fool me once, shame on you. but twice, shame on ME! i had a 1990 camry - it was great. and so i... FOOL! there will never, ever be another toyota.

i'll jury-rig this one. i'm stuck with it - i could never in a zillion years get anything like what i have invested in it. i can't enjoy it anymore. i hate the go**dam thing! every time i drive it i am waiting for the next ripoff...

These cars are 15 years old, but thats the general thought that old things break. I can tell you the electronics I design and built that go in my car, as some of them are close to 3 years old they show signs of age, if not failure. But then again, I'm not an automotive electronics engineer with a six figure salary with factories at my disposal.

I see two issues on the topic.

the first I bring up is, "they dont make things like they used to" Which to me, is beyond true. I am a mechanic at a large school district, and I can tell you, a lot the new equipment that is purchased fails or needs to be repaired more frequently than the older equipment or models. the worst was Western snow removal products. I've worked with older trucks with older western snow plows, and they were tanks. needless to say we got six new 2009 Silverados with all new plows and salt boxes. On all these trucks i had a 100% failure rate on conveyor motors on the salt boxes, and a 66% failure rate on plow pump motors. These units were not even 6 months old.

The other is how many things in the car now are electronically driven. If you look at a car from the 90s and compare it to a car in the 2000s, vacuum hoses are a rare breed, and everything now is wires. so where vacuum systems were used nearly a centruy and had constant R&D during their time, electronic control systems are rather new.

Though I stick behind "they dont make them like they used to" Toyota is notorious for their 8 million recalled cars, always leaving the spot light on them. But If I told you all the recall bulletins on all my GM vehicles, you would want to pull your hair out. (I mean, notlike brake pedal failure, but all sorts of little sh*t)

Oh, and for my relay board, everything has system limitations. theres power hungry mosfets on the board, so you fuse for the larger current draw, where the power needed to burn the resistors and set them on fire is smaller than an overuse of current though other components on the board. Sure, fuse everything, but that would be super c-c-c-crazy.

I'll get off my soapbox now.

 

[Jigg007]

So theres an hour left before i "should" go to bed, so I decide to tear my car apart outside in the dark, as usual.

Mmm, toasty! (that trace deserves a promotion)

Oh, haha, get it?

Because the boat was all burned up and traces destroyed, corrections had to be made.

Look ma, no smoke!

Dome lights are functional again, and there is no more magic smoke emitting from this fine box module.
CASE CLOSED.

Thanks for the help too guys.

 

[Chunkywolf]

Congrats on gettin it fixed up

 

[Jigg007]

And as long as I dont find a pile of ash in my driveway tomorow, were good!:naughty:

 

[Jack Deth]

nice work, and kudo's for using the flameproof resistors.:thumbsup:

 

[sonic2wb]

Did u trace down what caused it?

 

[Jigg007]

Did u trace down what caused it?

Yes. About a year ago I removed some underseat lighting I put in, via the door trigger. I discovered that I did not Insulate the terminated wires enough.