SR Tachometer Signal Wire

[jrmiller84]

Alright guys, so after I finished my build the last thing that I needed to fix was my tachometer. Since my car was a SOHC, obviously the stock cluster wouldn't work.

I recently bought an aftermarket tachometer and I can't seem to find my S13 SR's signal wire. From searching I found a couple of threads discussing which wire it was so I tried each of the ones they suggested but no dice. Many of the people didn't seem like they knew what they were talking about though. In particular this thread (http://www.zilvia.net/f/showthread.php?t=103227&highlight=sr20det+tachometer+wire) mentioned many wires such as a yellow/red striped wire as well as a green wire. Heavy Throttles writeup says the tach signal wire is the yellow/red striped wire so I tried that one first.

No dice. After that I tried the green wire. Same thing. Next I tried every wire on the harness that comes out of the ECU and runs to the gauge cluster and not one of them worked. I then tried a yellow/red striped wire coming from the ECU to the main engine harness and that didn't work either. I didn't want to start chopping my main harness up anymore so I soldered and wire wrapped everything back to how it was and came here. I also scoured the FSM and couldn't find any information as well.

Thanks for any help in advance guys. I really appreciate it.


Hopefully it's not the gauge...

[Z U L8R]

the yellow/red stripe is the tach wire for the stock dohc tach. your aftermarket tach won't read off of that.

call summit racing and have them order you msd part # 8918. it's a tach signal pick up. it's about the size of the tip of your thumb. clip it onto the white power wire that gives all your coil packs 12volts. the rest is self explanatory as it comes with instructions, basically 3 wires to wire the thing in, one is 12volt ignition power, one is ground, the other is the signal wire that goes to your tach's signal wire. best part is it's only $30 =]
Dave

[jrmiller84]

Really? I saw that someone was using one of these but I didn't realize everyone had to use it. I thought it was only for a specific gauge type. You would think they would include something similar with the gauge itself if it's so common.

Anyone else had to buy something similar? I'll pick this up tonight most likely.

[kognition]

First off, happy 4th :bigok:
This is a very gray area with alot of input from people who shouldn't really even be tapping into their ecu's without basic electronic knowledge. The safest and most reliable method of tapping a signal for your aftermarket tachometer that i have found, is to take it off of the tach input behind your gauge. I cannot verify that this will work for an S13 as i haven't done one yet. But i have on my S14 and other S14's in the past. I took this picture tonite of my S14 cluster which sits strapped under the racing dash i made. I peek at it only to see my fuel level, since i have not gone to a fuel cell yet. It should be abreviated "TAM" or "TACH" for tachometer. Crimp an eyelet terminal to the end of your tach signal wire, and unscrew the screw shown and re tighten. :2f2f:
http://kognitiondesign.com/tach_signal_S14.jpg

[kognition]

My bad, i see that you don't even have your oem gauge installed yet. Well, if you do get it installed, try the above method for your aftermarket tach.

[jrmiller84]

Yeah, it's still an SOHC cluster. I have adequate electrical experience I'm just not sure which wire is the correct one to splice into since none of them seemed to work. I'm piecing together my own gauge cluster as soon as I accumulate all of the proper gauges so all of this is only temporary. As soon as I'm ready, I plan on buying the cf cluster you offer actually, Kognition.

With all of this in mind, I plan on trying both methods. I went ahead and purchased that part to see if that would work and I'll try behind the cluster tomorrow afternoon.

My question is if the signal wire that comes from the ECU and goes to the cluster wouldn't work, how would the signal directly behind the cluster be any different?

EDIT: I see what you mean now, sorry. After I get the cluster itself working, try your method.

[kognition]

Yea it's just easier to tap the aftermarket tach off the oem tach signal. Shorter wiring job, and no guesswork and no mess at the ecu harness.

[Z U L8R]

if you get that msd tach pickup it'll work perfectly. if you've tried to hook your aftermarket tach's signal wire to the ecu's tach signal to guage wire chances are you probably burnt up that resistor in the ecu. therefore if/when you go safc2, if you can't get rpm's off of that wire, then you can on either of the 180 degree cam angle sensor wires that go to the ecu. the safc2 will read that beautifully and you'll be able to tune the air fuels for the given rpm ranges. you can also hook your aftermarket tach to the 180degree wire and it'll work ok but not perfectly, cause at high rpm's the signals overlap and the tach'll read like 1k-1.5k off at high rpms, however the safc2 won't have a problem reading off either of the 180 pins on the ecu.

if you pop the cover off your ecu you'll probably see that the resistor for the tach signal's popped, it's no biggie as you can bypass it with how i explained. good luck
Dave

[20 til 3]

There is no need to get a MSD adapter for a SR ECU. The MSD adapter basically translates the signal to your coilpacks into a pulse which allows aftermarket tachs to read from. The higher the pulse = the higher RPM. I did alot of research on this last year because I couldn't figure out way my stock and aftermarket tach didn't work on a S14. The thing about your SR ECU, is it sends information to your gauge by pulses anyway. YAY for Nissan for getting something right and not using some crazy signal.


Anyways, after much deliberation about which wires does what, you need to know that the CAS is what reads RPM, it sends a signal back to your ECU which in turn, your ECU translates it into 2 things. 1) Another signal for your coilpacks 2) Another signal for your tach.

Easiest way to find your Tach Signal wire is look at the ECU pin layout rather then looking at the what color is per wire. Go here http://www.apexi-usa.com/pdf/technicalDocumentation/200.pdf
find your motor, find your ECU pin layout. It's very simple.

Afterwards you need to test if your signal from your ECU is actually working. Take a test light to it and you should see it pulse. If you don't, your ECU is shot. If you do then you're getting somewhere, now trace the wire as far as you can into your dash, make sure it is connected. Now go to your Gauge cluster, find the RPM signal wire again, test it with the light, make sure it's working there. If not, you have a cut in your wires, if so, then your RPM gauge is shot.

Now here is where it gets a bit tricky, I bought a Defi Tach last summer and tried hooking it up, I did everything correctly and by the book, it still didn't work. I didn't have my Stock RPM gauge hooked up at the time either, so I write DEFI and get the explaination of "A SR ECU needs the RPM signal wire to essentially be grounded before it will send a signal, some type of resistor needs to be in place, the DEFI gauge did not provide that" so in turn I never got my Defi Tach to work. I ended up getting a new stock tach, I put it in and magically got power through the signal wire. Amazing. So I try the DEFI gauge again and it works with the stock gauge cluster, but will not work without it. Confusing ain't it?

Sorry.


Either way, go through the signal wire with a test light and should help you out.

[Z U L8R]

20 til 3 you missed what i was saying...

first, most people don't get aftermarket tachs for sr's they just get a dohc cluster. therefore this isn't even an issue.

the "tach adapter" is $75, it's totally different, and i've never gotten one to work...

use the above mentioned part msd #8918 tach signal pickup $30 and you will have a perfectly working tach, there is no ecu wires to mess with just the same, no pulling out your frickin instrument cluster, none of that. y make things harder...

i know for a fact putting an autometer's tach signal wire to the "tach signal" pin on the ecu will pop the resistor as i've done it once myself. it's no big deal to get around, it doesn't affect anything else, it's just better to not damage the ecu unnecessarily.

i've never tapped off the back of the cluster. it does make sense though, and it'd probably be the cleanest way to go, however......if the resistor in the ecu is blown, that won't work either as the cluster won't be getting anything anymore, therefore carry out the above mission LOL good luck

[mehsilvia]

First off, happy 4th :bigok:
This is a very gray area with alot of input from people who shouldn't really even be tapping into their ecu's without basic electronic knowledge. The safest and most reliable method of tapping a signal for your aftermarket tachometer that i have found, is to take it off of the tach input behind your gauge. I cannot verify that this will work for an S13 as i haven't done one yet. But i have on my S14 and other S14's in the past. I took this picture tonite of my S14 cluster which sits strapped under the racing dash i made. I peek at it only to see my fuel level, since i have not gone to a fuel cell yet. It should be abreviated "TAM" or "TACH" for tachometer. Crimp an eyelet terminal to the end of your tach signal wire, and unscrew the screw shown and re tighten. :2f2f:
http://kognitiondesign.com/tach_signal_S14.jpg

Struggle myself with an old Raptor shift light i had laying around, this ^^^ worked out perfect for me. the TAM screw was exactly what i was looking for and its now working perfectly.
And i do belive this shift light is not much different than your average TACH.

So thank you Kognition!

[kognition]

Glad it worked. :bigok:
Also, yes you can and likely will blow the output transistor on the ecu tach signal. I have had to repair these for people in the past.

Struggle myself with an old Raptor shift light i had laying around, this ^^^ worked out perfect for me. the TAM screw was exactly what i was looking for and its now working perfectly.
And i do belive this shift light is not much different than your average TACH.

So thank you Kognition!

[JohnC]

Good info!! thanks.

I got my Defi Tach coming in i a couple of days for my S14.
This thread, just in time!!!
Kognition,
Using your TAM method with my Defi will I blow the outpu transistor on my Power FC?

[jrmiller84]

So I got the MSD signal pickup today and installing it is pretty self explanatory, except for which wire to connect the pickup to in order to read the signal. I tried connecting it to the white wire, but there's at least 5-10 of them in the harness near the ECU. I also tried connnecting it next to one of the white wire near one of the coil packs themselves and that did not either. Are we sure it's a white wire near the ECU or am I looking in the wrong place?

EDIT: I wound up finding a wire that gave me a signal. It was a red/blue stripe wire before the connector that connects to the actual coil packs. I don't believe it is the best wire though because the gauge seems to be acting very "robotic," I guess you could say. In that it moves up and down the rpm range in a blocky, clicking fashion instead of smoothly moving up. It'll work for the time being, but does anyone know of a better wire? It's the only one I could find that would even give a signal. All of the wires mentioned from my searching turned up nothing.

[Z U L8R]

yeah, you want the wire that supplies 12volt power to the coil packs. in the engine bay, not in the car or near the ecu. if you look at the coil packs you'll see it says + sign. those wires all connect to the same wire at the big grey plug that separates the coil pack harness from the engine harness. if you really want to you can just clip it to the + wire right next to the coil pack, should work no problem, but if you trace those + wires they all connect and go to the big grey plug, i wanna say it's thick white wire or thick blue wire but either way you'll be able to trace em.

clip to 12volt coil power wire.

[jrmiller84]

Yeah, that's what I thought I just can't seem to get the wires out far enough for me to see what colors they are. The wires are all pack pretty tight between the firewall. The closest I could get was directly before and after that connector, neither of which has a white 12v wire. There was a collection of three red wires and three black wires but those did nothing. I'm guessing somewhere between the firewall and the motor there is another connector or some type of distribution that changes the wires into the appropriate colors as there is a white wire to each coil pack. Either way, I'll figure it out.

I may have to jack the engine up slightly to free up some space for those wires to move.

[kognition]

I do not know.

Good info!! thanks.

I got my Defi Tach coming in i a couple of days for my S14.
This thread, just in time!!!
Kognition,
Using your TAM method with my Defi will I blow the outpu transistor on my Power FC?

[JohnC]

Just wanted to update you all that I have found another easy, cheap solution and it is from Defi .

Defi sell, only in Japan as I have tried sourcing this elsewhere, a product called
Defi Rev Adapter
Defis pdf - http://www.nippon-seiki.co.jp/defi/c...revadapter.pdf
Here is a shop that sells it in japan, translated for you already
http://translate.google.com/translat...bb=1&ie=EUC-JP

$40 after shipping etc. and I now have a functioning Defi rev meter and oe cluster is gone.

Enjoy.

[kognition]

Good find. :rawk:

Just wanted to update you all that I have found another easy, cheap solution and it is from Defi .

Defi sell, only in Japan as I have tried sourcing this elsewhere, a product called
Defi Rev Adapter
Defis pdf - http://www.nippon-seiki.co.jp/defi/c...revadapter.pdf
Here is a shop that sells it in japan, translated for you already
http://translate.google.com/translat...bb=1&ie=EUC-JP

$40 after shipping etc. and I now have a functioning Defi rev meter and oe cluster is gone.

Enjoy.

[Slidin240Wayz]

Link don't work.

[jrmiller84]

^ ditto.

msglengthbbq

[JohnC]

http://www.nippon-seiki.co.jp/defi/car/images/df06301revadapter.pdf

this works, weird it did on the first post as well.


http://www.rakuten.co.jp/kodawariya/492853/499983/723278/
or translated
http://translate.google.com/translate?u=http%3A//www.rakuten.co.jp/kodawariya/492853/499983/723278/&hl=en&langpair=ja|en&tbb=1&ie=EUC-JP

[onesicklambo]

THANKs for the link! BTW i just got my defi working on my SR..with a much cheeper solution. Out a 5k pull-up resistor inline with the tach signal wire that goes to the blue defi tach signal wire...BAm its done:D

[JohnC]

Cool, who knows maybe that is whats in the defi rev adapter :)

[kognition]

I am prototyping a 10K RPM Digital Tach with large segmented LED display for my car. I wanted larger digits, so i found a 1.5" tall digit in green that i am going to try out. It will just sit in a small box about the size of a pack of cigs. And i can control my shifter light (simple large bright blue LED) in 100rpm increments. I'll
post my results next month for you guys. : )
Analog tachs just don't do it for me. And on the track, the only thing i am looking for is my shift light anyway.

[Dousan_PG]

i did mine off the coil pack harness


IIRC off the top of my head


its the fat blue wire

ill check today if anyone cares...

i use the DEFI and now i have the STACK off it
actually the tach adapter is off that

it didnt work until i had the tach adapter

[jrmiller84]

I still haven't got mine to work, signal pickup or not. I tried connecting it to pretty much every wire that goes to the coils underneath the hood, still no dice.

Not sure if the gauge is gone or I'm just being a dolt.

The latter is probably more likely...

[JohnC]

Kognition,

Please share when you got it all done.

[kognition]

I will, it's a really simple kit that you can buy online (tach kit) for about 30 bucks. And i am just making a jumper board to accomodate a larger LED display.
I have had this tach in my car to compare what my stock tach and my Autometer tach readings. It is dead on accurate, and super responsive. Then all you need is one of those plastic project boxes, and hook it in. Very very simple and cheap.

Kognition,

Please share when you got it all done.

[onesicklambo]

I still haven't got mine to work, signal pickup or not. I tried connecting it to pretty much every wire that goes to the coils underneath the hood, still no dice.

Not sure if the gauge is gone or I'm just being a dolt.

The latter is probably more likely...


try to take a ignition wire, put a 5k resistor in line, then T that wire right where the yellow/red meets your defi blue wire

[kognition]

Are you trying to connect an aftermarket tach? Or a cluster?
I still haven't got mine to work, signal pickup or not. I tried connecting it to pretty much every wire that goes to the coils underneath the hood, still no dice.

Not sure if the gauge is gone or I'm just being a dolt.

The latter is probably more likely...

[jrmiller84]

Are you trying to connect an aftermarket tach? Or a cluster?

It's an aftermarket Tach, not a defi but very similar.

It has your typical signal wire (obviously) and I picked up one of those Summit inductive signal pickups.

I've tried the signal pickup on all of the wires going to the coil-packs under the hood I believe. Every once and a while I'll get a signal out of one of them but it's never accurate. It may be that the gauge is dead or the signal pickup is, or maybe I'm somehow missing the wire I really need after all.

A lot of you speak of a blue wire leading to the coils, I don't believe have a purely blue wire. I think I have a blue/red stripe wire.

EDIT: I forgot to mention, I don't know that I completely trust that signal pickup either. All of the wires are so close together in that loom that there has to be quite a bit of interference. Maybe I'm wrong but it's something that's crossed my mind more than once when I see the needle act erratically (when it does work at all).

[kognition]

I looked at your first post, and you mentioned that you tried all the ECU wires? :eek: :tweak: You probably blew your output transistor on the tach output wire of the ECU when you hooked it up directly. I have done this before, and it required me to go in, remove the output transistor and replace it with one from my old automatic ECU. Then after that, i hooked the tach wire up to the back of my cluster in the pic i posted. There seems to be some kind of bias resistor on the back of the cluster connected to the tach output signal there. I know this does not solve your problem completely, since you are unable to make your cluster work. But i think you damaged the transistor in the ECU tach output.

It's an aftermarket Tach, not a defi but very similar.

It has your typical signal wire (obviously) and I picked up one of those Summit inductive signal pickups.

I've tried the signal pickup on all of the wires going to the coil-packs under the hood I believe. Every once and a while I'll get a signal out of one of them but it's never accurate. It may be that the gauge is dead or the signal pickup is, or maybe I'm somehow missing the wire I really need after all.

A lot of you speak of a blue wire leading to the coils, I don't believe have a purely blue wire. I think I have a blue/red stripe wire.

EDIT: I forgot to mention, I don't know that I completely trust that signal pickup either. All of the wires are so close together in that loom that there has to be quite a bit of interference. Maybe I'm wrong but it's something that's crossed my mind more than once when I see the needle act erratically (when it does work at all).

[kognition]

I got my large led display today :x:
Now i just need to make a jumper board and put it all together. The led color is green, and this is a perfect dash mounted size for my car.
http://kognitiondesign.com/led-display.jpg

[jrmiller84]

Damn, those are huge.

Looks like you stole them off of a scoreboard somewhere, haha.

Should be cool when it's done though.

I'm thinking about getting another ECU for my car to see if I did blow the tach functionality. A Power FC unit would fix that too, correct?

[kognition]

This digital tach will be the bomb for my car. An opaque filter goes over the front of the displays so you do not see the actual display body itself. The digital tach will read up to 9,900 rpm in 100 rpm increments.
I don't know about the power fc fixing your tach driver problem, i haven't any experience with a power fc.

Damn, those are huge.

Looks like you stole them off of a scoreboard somewhere, haha.

Should be cool when it's done though.

I'm thinking about getting another ECU for my car to see if I did blow the tach functionality. A Power FC unit would fix that too, correct?