My son smelled smoke coming from defrost vent after he started up and began to go (car parked in sun on a very hot day, windows up). Said it lasted just a minute as he drove on and all was ok. "Oh really"!

1) Most of the cluster lights are super dim if at all, while some work fine.
2) Daytime running lights don't work, yet headlights are working fine.

Dimmer switch is good/ Headlight switch is good (both tested with 3 known good ones each). Didn't see any burnt wiring while popping in/out the good switches.
I'm weak in the "electrics". Could this be a relay? which one? where? Any help at all is needed. (BTW, all dash indicators are ok)

 

Go to k-jet.org to download wiring diagrams and other electrical info (e.g. component locations) for Junctions/Components/ harnesses.

Regarding "weak in electrics" -- I am old-school, things have to make sense, so logical things appeal to me. "Electrics" is very logical. Spend 10 minutes with the diagrams and you learn a lot about your car.

What year is your car?

 

What kind, year is your car? You say that you replaced the dimmer & head light switches 3 times? Have you replaced any bulbs? The smoke smell could have beed something outside unless he actually seen smoke.

 

Whoop, sorry. That would be: 96' 850 glt sedan ,auto, non-turbo,112k.
Son did see smoke come from vent("smelled like something burning but not wood"), scared, pulled over, shut car off, waited for air to clear, restarted and drove on without any issues
Yes, I popped in spare switches- 3 dimmers/ 3 headlight that I first tested on friends car, so I know they worked fine.
Didn't replace any bulbs because headlights work in "headlight mode" but not "daytime running" mode, and some of the cluster bulbs in question are lit but super,super dim while others seem to be out.
I too like logic and realize when you "break things down",(no pun intended) it all makes sense. I'm also an 850 owner so I dabble in the occult too!
Will try my hand at reading wiring diagrams.

 

Smoke from the vents, i.e. smoke traveled inside the duct, or from around the vents? I understand you have circuit issues with dash lights, but do you have any issues with the blower / Heat / AC?

Center vents or side vents?

It sounds like something may have melted there. There are a bunch of relays behind there so based on the diagrams you would know which ones to check. I would also check the grounds too.

 

No issues with heater, blower or any vents. Not being there as it happened I assume something fried behind the dash and the smoke just waifed up top, and appeared to a novice, to be coming from the defrost vent. I have pulled the dash in the past for odometer gear(well before this issue) and wish to avoid it for troubleshooting until I have some idea of what to check,expect or look for. It seems no matter what the problem is, someone else has had it and can direct you to the list of most common culprits. I'm sure this problem will "nag" me until I just read-up and take a look.
Thanks for prodding me to look at wiring diagrams. I can always use the "power of knowledge"

 

Problem solved. Got free cluster (with good bulbs) & some relays from a friend so I pulled out my cluster hoping to find an obvious "meltdown" behind the dash. All looked good so I changed out the cluster bulbs and just before install I noticed a fried wire from the headlight switch down to a relay. About 18" was fried down to bare wire. Luckily 5" was good from the switch and 3" good into the relay so I was able cut out the bad and splice in some new wire. The route of the old wire had spots where it could have been rubbing on metal so I hope that was the cause of the short. I didn't notice the wire when I first inspected the headlight switch because the wire was good for 5" and it wasn"t until I had the cluster out that I could see everything clearly. It has been 3 months and no problems. Daytime lights working, cluster lights working !