Instrument lights - Dimmer Problem?

[1991240xs]

1991 240sx hatch

I have a problem with my instrument cluster lights. The blinkers, high beam indicator, and idiot lights all work..but none of the backlights work to light the speedo, tach, gas gauge etc. so i can see them at night...I replaced the bulbs (3 194's)I checked every fuse in the car(with a fuse tester)I pulled the ?'tcu'? And visually checked all the circuitry and couldn't find even the slightest burn mark or anything on the back of it.

Now it appears that only the lights that are suppose to dim by the dimmer switch aren't working...so is it the tcu or the actually dimmer switch...anyone have any idea

[Silvia007]

My money's on the dimmer switch. Stop by a local junk yard and dig one up for pennies or free if you stick it into ur pockets, but while ur at it, get both the tcu (or what ever it is) and the switch.

[Silvia007]

I just remembered, there's a ground wire inside the stereo area that causes the dash lights to not work if it's not grounded... I'll find the color and let you know what it is. That's what happened to my brothers 91 hatch and he had the same problem as you.

[1991240xs]

sweet..ya let me know and i'll check it tommorow...is it just a ground for the stereo or is somewhere behind the stereo ?

[topless@vabeach]

Do you own a multimeter? If so set it to ohms scale and put one lead on the input to the dimmer and the other on the output. Now rotate the dimmer and the resistance should go up or down depending on the which way you are turning the dimmer.

You can also go to the bulbs that are not turning on and using your meter on the DC volt scale and check for volatege. DC scale will say DC or be a straight line like this -. AC scale will say AC or have this symbol ~. You can buy a cheap meter, roughly 10 bucks at radio shack.

[kansas240]

the dimmer switch doesn't have a resistor in it, the resistor is in the tcu, i have this same problem and my money is on the time control unit. do the lights that light up the rest of the interior work? my pop up, defrost and cruise switches don't work eiher. if you ever find what wire that needs to be grounded let a brotha know. i bought my 91 coupe about 3 months ago, previous owner hacked the wiring for an alarm and cd player, wiring is all messed up. i have a fsm if you need scans.

[Kevlar]

I am positive it is the timer control unit...I have had the same problem with you and replaced it with a unit I found at a junkyard (Which those hicks charged me only 5.00 for, I think it is about 100.00 at a dealer) and the lights worked after...