Instrument Panel Lights Don't Work!!! Have Tried Everything. Help!

[boryan]

I bought the 92 Nissan 240SX half a year ago. Besides burning some oil, it runs strong. This car's body is in one of the best shapes I have seen for a 240 in New England. Anyways, the car's instrument panel lights are out.

The previous owner said that they went out after the installation of the stereo or subwoofer. This car has an oldschool blankpunkt cd player. It also has wires running to the trunk where he had an amp and subwoofer box that he took out when I bought the car. He added some 2" speakers to the doors which are connected to an amp under the seat. The front speakers are running of the same amp. The rear speakers are still connected to the stereo.

Anyways, I feel like I checked everything and don't know what else to check. I checked the fuses under the steering wheel, on the left of the driver side wall. These were all good. I also checked the accessory relay under the hood. Pulled out the dimmer switch because I thought that it might be burned out. Tried to switch it in with two others from a salvage yard. Still no luck.

I finally decided to pull out the stereo and see if he shorted anything or didn't connect something. Turns out that he hacked the thing together. He cut off the nissan wire harness and was connecting it wire by wire. A lot of the wires were exposed. So I cleaned it up and I am driving without the stereo right now, but my instrument panel lights still don't work.

WHAT ELSE SHOULD I CHECK?

Any suggestion appreciated.

[le_ryan]

hey buddy, im in the same boat, my spedo lights dont work either, and i do think it has something to do with the aftermarket head unit... i bought my 91" 240 and the guy i got it from sayed it had been that way ever since he installed the radio, i checked and replaced all the things you listed, and im still lost,....well i hope some ones got an answer for us, as of now im driveing with a red neon light installed behind the plexiglass on the spedometer, looks cool and clean but i want my lights...

[Rusted_PS13]

I'm in the same boat as you two also, you guy's tried replacing the bulbs? I tried to from another gauge cluster and i still get nothing. I was wondering if it were the gauge cluster itself or the wire harness.

[4cefed]

This may not help, but make sure the wires on the head unit are connected to things they should be connected to. SOme people just match wire colors and go. I know with the dodges, the radio has a ground strap to ground the radio. There is a black wire in the harness that everyone tried to ground the radio to. THis wire is hooked into the parking light and cluster lights. I would comletely detach and insulate every wire going to the head unit and then check for bad fuses.

[boryan]

Hey guys. I am proud to announce that after a couple of hours of searching online for through forums and looking at the nissan 240SX wiring diagram i figured out the problem with the wiring lights. It turns out that it is a common problem in 240's. If you have had an after market stereo installed in your car and the factory nissan wire harness was cut off to wire the new unit there is a big chance that your TCU is burned out. The TCU is a timing control unit. It is a small white box that is located to the left of your fuses that are under the driver side dash. You can either replace it by pulling one from a car at a junkyard or pay a lot of money for one at a dealers. The other choice is opening the little box up and soldering a jumper wire over a trace which is burned out with a soldering iron that you can buy at radioshack for 5 bucks. Soldering it will only take a minute if you have the skills. The problem is the circuit that lights the dashboard lights, as well as the climate control knobs, and glove compartment is powered by a red wire with yellow stripe (-) and red wire with blue stripe (+). These wires also go to the wire harness for the stereo and are usually not used. If they are touched together during the stereo installation the TCU gets fried. Usually the fuse in the dimmer switch should go first, but after opening the TCU, I have found that the PCB (printed circuit board) is made by hand. I have some experience in PCB design and notice a lot of design errors. The traces that run on the board are to thin in some areas, so the TCU is the first to go. I have found out some posts that says that they fixed the problem by grounding the red wire with yellow stripe. This will fix the problem, however the dimmer switch will not work after you have done that.

Good Luck Guys, Tell me if this works for you.

[Rusted_PS13]

So all you did was replace it? No wiring involved?

[Rusted_PS13]

Is that the white box you were referring to? And if you can tell me what that harness is for and where it goes, the one hanging with the rubber around the plug.

- Mikey

[boryan]

Yep, that is the white box that I am talking about. If you take it off and unscrew it, you will see a Printed Circuit Board with a lot of mounted components. The side with fewer mounted components that looks like it has green paths running around will most likely have one of those traces burned out. You can tell if its is black. I didn't replace my unit and just fixed it buy soldering in a wire where the burned out trace was. But if you find that yours is burned out you can just replace it, and that will fix the problem too.

Sorry don't know what other wiring harness is for. Probably for some power option that your car doesn't have installed.

Hope this helps,Boris

[sileightysomeday]

had the same problem, i replaced the TCU and voila! dash lights.

[teddy]

i would actually suspect the illumination ground first before the TCU. both are common lighting problems in the 240's, but my problem was the ground. there is a wire that is behind the cd player that was hooked up to the factory radio, but when you switch to aftermarket, theres no spot to connect it to. It's a single wire with a plug on it. All you have to do is ground it which most people dont realize to do. I did it and all my stuff works now.

[MS180SX]

yeah i had the same problem when i put my radio in. I even bought the plug and play connecters so i didn't have to cut any wires. It turned out to be some ground wire. I would have never knew, but my friends father was a mechanic and he checked it out for me and found out that it was the grond wire. We ran a new one and problem solved.

[Rusted_PS13]

i grounded my CD player to those metal brackets behind the cd player, it might not be a proper grounding place, but where did you guys ground yours?

[AZhitman]

Great stuff, Boris!

Thanks for that - Looks like we need to make this an article!!!

[boryan]

The single wire that you are talking about is probably the red wire with yellow stripe that I mentioned earlier. It is the negative voltage signal of the circuit. If you burn out the TCU, that signal stops being grounded. I have read a bunch of other forums and a simple fix for the burned out TCU is to just ground the red-yellow wire from stereo harness. My lights started working when my TCU was burned out and I did this; however if you ground that wire, you will be shorting your dimmer switch and will not be able to control the brightness of your lights.

I'm interested to see if that is your case. My stereo harness wired right now so that only the black ground wire from the stereo is connected to the frame of the car (ground) and nothing else. NO WIRES COMING OUT OF THE STEREO HARNESS SHOULD BE GROUNDED.

[MS180SX]

The single wire that you are talking about is probably the red wire with yellow stripe that I mentioned earlier. It is the negative voltage signal of the circuit. If you burn out the TCU, that signal stops being grounded. I have read a bunch of other forums and a simple fix for the burned out TCU is to just ground the red-yellow wire from stereo harness. My lights started working when my TCU was burned out and I did this; however if you ground that wire, you will be shorting your dimmer switch and will not be able to control the brightness of your lights.

I'm interested to see if that is your case. My stereo harness wired right now so that only the black ground wire from the stereo is connected to the frame of the car (ground) and nothing else. NO WIRES COMING OUT OF THE STEREO HARNESS SHOULD BE GROUNDED.

by george i think your right.. oh well if i could see how fast i was goiong at night, i didn't care how brite my guages were. oh well

[teddy]

Well I dont have a cd player/radio in at the moment, so I just grounded the red/yellow wire. I did notice the dimmer doesnt work, but my gauges arent blinding either. I also know for a fact that when my lights were not working, my TCU was not burnt out. So other than grounding the illumination wire, or replacing the TCU in your case, I'm out of answers.

[Rusted_PS13]

umm what if the red/yellow wire for the illumination isn't hooked up to the cd-player at all?

[boryan]

See if your red/blue wire is connected to anything. This wire is the positive illumintation wire. It shoud not really be connected to anything. If that doesn't fix it, something else should be burned out in the circuit so that the yellow/red wire isn't being grounded. Ill check the wiring diagram tonight and let you know. By the way how did you check your TCU? Did you get a chance to open it up?

By the way Rusted_PS13 make sure that both your wires, the red/yellow and red/blue aren't hooked up to anything.

[ricebike]

to add...

Quote » And if you can tell me what that harness is for and where it goes, the one hanging with the rubber around the plug.

- Mikey[/quote]that plug hanging around there is the consult port of OBD I-equipped cars.

Ya know, the dealership-scanners plug into to do the trouble code readings as well as taking live readings while test driving the vehicles...etc... instead of pulling the passenger side kick panel, these guys get to interface w/ the car's pc thru this thing!

There are members who have made the interface, I believe, but I didn't pursue this further because I am not in that level of tuning @ all.
Modified by ricebike at 7:47 PM 8/27/2005