Instrument light weirdness

Dracov

Base model n00b
Oct 21, 2006
16
0
0
Broomfield, CO
This is a bit long-winded, so sorry in advance; I just want to thoroughly describe the issue at hand.

So my Supra decided that I was getting too complacent in its reliability. After running around town taking care of errands today, the backlights for both the instrument cluster and the climate control go out entirely when heading home. Indicator lights on the climate control as well as the temperature display are out. The blower controls still work, exterior lights were all still functional.

I checked the dimmer control and it affected nothing. All the indicator lights in the dash (TEMS, ABS, CEL, high beam, turns, etc etc etc) still worked. Indicator light for cruise control did not. Defroster indicator still worked. The weird thing I noted was the hazard switch backlight was on but very dim as though it was getting far below normal voltage. During the last leg home, the gauge backlights flickered a couple times but didn't stay on. I let her sit a while.

A couple hours later I came back and fiddled with the combination switch. Now the backlights were working just fine, but not due to anything I did as far as I can tell. The climate control backlights came back...but only in "on" mode. As soon as the engine starts, they go out. Instrument backlights still working when the engine is on. And to add to it, if the headlights are off, the indicator lights and temp display on the climate control will work, but they go out the moment headlights are turned on. The dimmer control does work...for the lights that still work anyway.

So, I'm fairly certain it's not a fuse, since that would just kill it entirely, rather than this random functionality nonsense. I have not done any electrical work to the Supra. I didn't recently take anything apart, put anything together, add nor remove anything physical or electrical.

As a note: I did convert the dash lights to a blue LED theme, with the hazard switch in red. The climate control is also in a blue LED theme. But the instrument cluster and switches were done a year ago. The climate control was converted about 4 months ago, so I'm not seeing those changes as a likely cause. This is irritating me as it's being very random about it, so I'm not exactly sure where to start looking. Any ideas?

Cliff Notes: LED converted dash/climate control. Worked fine for a year, now going schizo with respect to when they work and then they don't.
 

Dracov

Base model n00b
Oct 21, 2006
16
0
0
Broomfield, CO
I checked the rheostat already, as mentioned.

Now however, the interior lights are completely out on the instrument cluster, switches and climate control. In addition, the exterior lights do not come on with the combination switch. All fuses are fine. There is the tell-tale clicking from a relay when engaging the exterior/interior lights, but nothing happens otherwise. Turn/hazard/brake/door/ABS/CEL/battery/birdcage lights all still work. Headlights, fogs, reverse and brake lights still work.
 

sneakypete

Regular Member
Jul 18, 2007
1,129
0
0
Central NJ
ive actually been having a similar problem. the only thing is that it happens when the car is off.
i get in the car and step on my brake before i turn it on. the gauge cluster lights start to flicker. it only happens for a minute or two. and then it stops. when i start the car, it may happen for a few seconds or less. a few times ive noticed while driving that the clock and climate control lights start to flicker a bit, but didnt put the two together until i saw the gauge lights starting to flicker.
ive been searching for a few days and cant find anything
any help would be great
thanks
-pete
 

Dracov

Base model n00b
Oct 21, 2006
16
0
0
Broomfield, CO
Didn't get it solved, but found basically what was happening. There's a massive short somewhere in the instrument light circuit. While I was poking around with a friend we found the tail fuse kept popping. The relay was burning hot to the touch as well. After fixing that, the wires on the instrument cluster going to the lights started melting through. Killed a few of my LEDs on the instrument cluster too. It's been too damned cold to bother going through everything with a fine toothed multimeter, so for the moment I've opted for an ugly hack to bypass the shorting circuit long enough for my car to be road legal and let me see the gauges. Unfortunately this means the climate control lights are out of commission until it can be fixed properly.
 

sneakypete

Regular Member
Jul 18, 2007
1,129
0
0
Central NJ
this sucks. my cluster lights work when the lights are on. i just dont want any future damage. i dont know where to look.
all i know is that is directly related to the brakes because they only flash when i apply the brakes.
i bypassed the lamp failure box in the trunk because my brake lights have been going out and theyve been fine every since