Ok so I got my 240sx near completely fixed, now its time to tackle the gauges. Ok so the past three owners of my car haven't had working gauges...lol.
The last owner replaced the cluster and the dash in an attempt to fix it with no luck... I still have the spare gauge cluster.
I was told to replace "the little brown thing next to the engine bay harness" not sure what that exactly meant untill I saw a few open hood pictures which showed a little brown box near the passenger side firewall, is this what im looking to replace??????? I figured it would be the most logical replacement part for the fix because I doubt its the dash wiring or the cluster,and guy said the only other part to replace was " the little brown thing ".
I just want a second opinion before I go on the prowl for parts.

What part of the cluster is not working? When I got my car it was from a hach artist that chopped all the wires that go from the ecu to the dash (8" section or so) all those wires run your cluster. I had to wire everything straight to cluster. I can walk you through it.

The speed rev gas temp oil etc don't work. The red light and the white spot maybe the clock IDK they work.
That's why I was wondering about this "brown thing" I think I don't have one I was trying to get some more info to see if I'm missing something I need

Usually when there is wiring issues from ecu to dash harness you will still have the gas gauge working assumeing the sending unit works. But with the last. Conversation we had who knows with that one. My guess is there is a main power that runs all the gauges that is dead. If you pull the cluster With it still plugged in test for power to each unit with key on. The "circuit board "on the back is very easy to read. I don't know about any "brown thing", the diagnosis for each individual gauge shows wiring straight from unit to gauge in. The fSM. The only thing I can. Think of that is a "brown thing" is 89-90 240sx plug from ecu to dash for the gauge cluster is brown. Where do we start?

Where do we start? lol yeah that was my first thought. The reason I even started this thread was because the kid who told me about the "brown thing" has owned 36 nissan 240sx's both s13 and s14 , he used to work at some kind of salvage yard and would buy them for $200 and part them out to make money on the side. I figured he might know what hes talking about but IDK ,I'll give him a call for some more info. but we'll figure it out.

I know the last owner of my car personally, we grew up together he is the one who replaced the dash and gauge cluster, Im sure if he was trying to get the gauges to work he would have took the dash wiring in to consideration, im sure its not cut or destroyed like what you had but probably like you said I just dont have a main power source or something. Im gonna have to buy another voltmeter mine crapped out.

Maybe if there is a brown thing we will both learn something. Once my gauge cluster and running lights kept going out because the fuse kept popping. When I change all the bulbs to blue in my cluster. I decided to turn the lights on with the gauge cluster disconnected and the fuse didn't blow. I started checking all the wires to the cluster and the ground had power. Cut it and regrounded it and fuse to this day hasn't popped. To this day I have no clue what caused it.

the brown harness is under the dash passenger side behind the glove box, well it is brown on certain years of harness. im assuming a dohc swap has been done? well u have to match those little "tails" for the gauge cluster to work, all the right wires are there and the colors match just the pins dont line up. u can re pin or solder or crimp or what ever u like.

i wrote this in a different post, it should help with ur tach at least

"I recently swapped a 93 dohc ka24de into my 90 240sx
along with some hassles making the wiring harness match the engine i started to wonder why the stock tach wouldnt work. the answer is simple
power
there is no power wire running to it, the fsm says its a yellow/red wire that powers it. which is true and i will get back to that in a second.
my new engine has a dizzy coilpack unit, not separate like the sohc, the two together needed a 6 pinned connector and a 2 pin, the harness had a 2 pin a 3 pin and one 4 pinned connector, the 2 pin clicks in, u then have to splice the 4 pin and 3 pin together to make a 6 pin. thats fine and great, but on the 3 pin after u splice there is one wire left, a green/ black, that powers ur tach, run that down to ur ecu and splice it in with ur yellow/red and voila u have a working stock tach! if u notice on ur ecu there is two yellow/reds thats fine, splice it into the one that goes the lowest on the harness, or locate the pig tail smaller sub harness and follow that one in!"

Not to bring this thread back to life but I have had this same issue. I have a S13 redtop swap done. I bought the car as a shell and was never told if the gauges work or not. None of my gauges work. The clock still works and from time to time the dash lights will come on but no gauges. The low fuel light only works when i wants to. I have already checked the wireing and everythings good. Im starting to think its maybe just the cluster but im not sure. Then I saw this little brown box thing and it makes me wonder. Have anyone replaced this to see if it works yet?

Nope still haven't figured it out. I know in my case all of my cluster doesnt work and I spoke to another one of my cars previous owners and they said it used to work, so the guy who sold the car to me already replaced the dash and cluster after it already wasn't working, so its most likely wiring, but I also never got any real closure on the brown thing. But now im having other electrical problems my cd player just quit working out of no where. My headlights dont pop up anymore, and my power windows aren't working.
Ideas anyone ???? my car has sat for almost two years so im not sure all of the possible causes.

So I know of a way to fix two of the gauges. For the tach run a wire straight from ecu plug (the part that goes from engine harness to behind the glove box) to the gauge cluster tach input. For the coolant gauge run a wire straight from single prong cts to temp input on the cluster. I had a fuse box short internally that gave me some similar issues. Check power and grounds. How I found it was the wiggle test.

Do you think I am going to have to take the dash back out??

No you wont have to. All the wiring and testing is right there on the back of the cluster and behind the clove box.

just got the cluster out, now im studying the EL on how its supposed to work. wish me luck

Well I've discovered that im not so great at reading wiring diagrams.
If anybody knows how ,or has tested their gauge cluster please shed some light. I just want to see if im getting power, and trace the source of my problems.

Ok so if you look at the back you will notice each line is. Labeled with an abbreviation. For power there is the left plug, bottom, left middle. If you fallow it it says ign. If you notice. When you trace the maze ign only goes on the outside of bulbs etc. When a component or dummy light needs to be used it grounds the circuit from ign. Check to see if you have 12v at the pin mentioned and we will go from there. If you have any questions ask away... I have a cluster right in front of me.

I was just outside testing a few things before I checked the thread. I unplugged the three clips and tested them for power and got no more than 0.01v on the left and right clip, I got 12v on the blue wire in the middle clip and 0.01 on a few other wires

Ok so heres my cluster

This is the only place I saw the letters IGN, between the middle clip and the right clip on the top right bolt ( triangle of bolts)

Im getting almost 40 Mv on the third pin from the left on the left clip

here on the middle clip im gettin 12v on the blue wire which I am touching


Please more tips on how to fix this, baby steps lol

ok so you looking at the cluster upside down? If so than lets start with ign. Right behind the coolant temp gauge between the plug and dummy lights there is ign right next to a screw. Fallow the circuit to the plug. Should be second pin right next to brk. You should have 12 v there with Ignition switched on. What does the blue wire go to? Ill+ or the one where it dead ends to the solder?

Haha! Never mind, I found an extra gauge cluster harness! The blue wire is 12v ill+ (illumination ) for gauge cluster bulbs. Check voltage at the green wire with silver dots and let me know. It might be Ignition switch ground (ign). Also check red wire with black stripe. That one says batt I bet you don't have voltage there.

So im pretty sure I figured it out. The "ign" wire (green second pin in) needs to be cut and ran to an Ignition switched source. After taking mine apart and fallowing the circuit board sheet I found that that is the wire that powers ALL the gauges! 40mv means you have a short somewhere. Oh and by the way if your clock works than you have 12v on the red/black wire(batt) which only powers clock (which would also indicate that the grounding is good) good luck! I hope this solves everything!

Hmm I will go test the green wire now.
But when I tested the IGN circuit , and the brake circuit where you mentioned before I have no power both the yellow/green stripe and green/yellow stripe on the right side.
I'll go test that green wire its probably why I dont have power on everything else. BRB

compactfean wrote:So im pretty sure I figured it out. The "ign" wire (green second pin in) needs to be cut and ran to an Ignition switched source. After taking mine apart and fallowing the circuit board sheet I found that that is the wire that powers ALL the gauges! 40mv means you have a short somewhere. Oh and by the way if your clock works than you have 12v on the red/black wire(batt) which only powers clock (which would also indicate that the grounding is good) good luck! I hope this solves everything!

Ok so heres what mine is doing , IGN green wire only has 1.3v, Batt/ red+black stripe has 0.01mv.
Looks like its time to re-wire my cluster

ShouldaHadaV8 wrote:Hmm I will go test the green wire now.
But when I tested the IGN circuit , and the brake circuit where you mentioned before I have no power both the yellow/green stripe and green/yellow stripe on the right side.
I'll go test that green wire its probably why I dont have power on everything else. BRB

So I just noticed that there are two brk's. One is brake light and the other is seat belt light. The yellow green wire is seat belt and the yellow purple is brake light. What green yellow wire are you testing? I would just wire the red/black to 12v constant and wire green to 12v switched before doing anything else (once you have power everything should work)

Oh one more thing...your missing a small bulb on the far corner! Lol.

I dont have 12v at the red/black, and I made a mistake I was testing yellow/green and GREEN ( ignition). but im going to use a quick jumper wire from the constant on my cd player to see if it works when i give it 12v.
Hey your right i am missing a bulb LOLS

You had me confused for a second but cool were on the same page. That's crazy you don't have power to neither! For that bulb just use one of the dummy lights you don't want. (I got rid of almost all my dummy lights) im excited to see what happens.

The jumper worked, I ran it to the green wire and my red bulbs and brake light lit up, so then i ran it to the red/black and my clock worked so now I know I dont have power to the gauges. my battery is to dead to start the car to see if the speed/rev work. im going to jump it in about an hour when my GF gets home.

Ii just thought of something. A good 12v constant you could use stereo memory wire for clock.

I just had one of those sniff sniff WTF is burning moments.
NOTE : Do not test cluster, while jumping your car to another car, and using the cd players constant power. You will melt the jumper wire.


So Im just gonna skip the try and make the speed-o-meter work for now. where do I need to be testing now to get this constant power right. you said under the glove box was another testing point, if so its already out. The ecu is uncovered as well

No, the only thing in the cluster that should have constant power is the clock (red/black wire) and green should go to 12v switched. The only reason that wire would do that is if you have power going through the ground or you had memory wire to green when cranking . Unplug the plug and see if the green wire is a grounded (continuity ) or see if your ground black wire has power (it shouldn't and that's what happened with me and my lights ) the wires behind the glove box are just signal wires to the cluster. Do you have it set up so everything has power? If so then from there we will diagnose each gauge individualy.