Tach coding plug question

[Mr Mpower]

for more information
i have a 1983 318i k jetronic and my cluster is vdo with that type of codie plug, it have the number "04" and it have broke up the positions "2", "5" and "8".

[Eecen]

The plug is long but the only part that does anything is right near the shaft, there are a series of hollow bits (top left corner of photo) with the outer most parts broken out on some of them. The plug shows evidence that it started life with a full solid circle as there is tearing where they are broken.


My plug is coded 09 on the end, this end is why its so long, if you look the the left center, you can see on the face of the economy meter there is a small hole above zero mpg and to the left of "02 usa" the end and its number (09 on mine)is usually visible through this.

In that same part of the photo you can see a black plastic ring with small metal bits(backs of outer ring) showing, thats where the breakout ring(on the black plastic coding pin) fits into and does the "coding" bit. Looking now at the circuit board where it is attached you see the inner 10 pins soldered, the thing to note about this is that whole inner ring is electrically connected always, (you can see them all connected but with a bit of the green masking material covering the ring trace) and that ring all connects to the trace that leaves the left of the inner solder pad labeled 1(bottom right of 1).

So what happens is when the plug is inserted it connects every pin from the inner ring to every pin on the outer ring EXCEPT for what ever pins aren't being pushed because your black coding pin has those sections broken out... this mean if you want to emulate having a coding plug inserted into this type of tach you can just solder jumpers to whatever ones for the plug you are supposed to have... in the bottom right of the pic you can see where you would solder jumpers to emulate having a 09 plug like mine...

The problem is I have no idea what cuts are on the other numbered plugs or what car is supposed to have what plug. All I know is this seems to work for my 2.7l 325e and future forum readers might find it useful.

;)


Interesting

[ErikVonVicious]

you dont need the plug, all it is is plastic, if you have the cluster you should be able to get it to work. for help Ive attached a photo of the old style plug thats in my 87 325e but the cluster seems like its from 83 going from the stamp.

the plug is long but the only part that does anything is right near the shaft, there are a series of hollow bits (top left corner of photo) with the outer most parts broken out on some of them. The plug shows evidence that it started life with a full solid circle as there is tearing where they are broken.
my plug is coded 09 on the end, this end is why its so long, if you look the the left center, you can see on the face of the economy meter there is a small hole above zero mpg and to the left of "02 usa" the end and its number (09 on mine)is usually visable through this.
in that same part of the photo you can see a black plastic ring with small metal bits(backs of outer ring) showing, thats where the breakout ring(on the black plastic coding pin) fits into and does the "coding" bit. looking now at the circuit board where it is attached you see the inner 10 pins soldered, the thing to note about this is that whole inner ring is electrically connected always, (you can see them all connected but with a bit of the green masking material covering the ring trace) and that ring all connects to the trace that leaves the left of the inner solder pad labeled 1(bottom right of 1). so what happens is when the plug is inserted it connects every pin from the inner ring to every pin on the outer ring EXCEPT for what ever pins arent being pushed because your black coding pin has those sections broken out... this mean if you want to emulate having a coding plug inserted into this type of tach you can just solder jumpers to whatever ones for the plug you are supposed to have... in the bottom right of the pic you can see where you would solder jumpers to emulate having a 09 plug like mine... the problem is I have no idea what cuts are on the other numbered plugs or what car is supposed to have what plug. all I know is this seems to work for my 2.7l 325e and future forum readers might find it useful.

[highoutput]

Thanks for the info, buy idk where I'd get just that plug ( if anyone has one , let me know). It seems only the old clusters had them so I'm sure theres not to many around. I'm just going to end up getting a new cluster eventually.....

[Hobbes]

All E30 dashes have some type of way to change from 4cyl to 6cyl or to change injector size. The older ones had a physical plastic plug thing in the back of them instead of the chip that goes in the front.

Edit: http://www.e30tech.com/forum/showthread.php?t=96921 - See post 7 and 8. IIRC, an eta plug in a 7k dash that is running a 24v or 2.5 m20 will read correctly. I made a dash for a friend from a broken 325e dash and a M10 7k dash and it worked fine on his NVm50.

[RoadHazard]

It won't work 100% because the m3 tach redlines at 8k the needle will deflect to what it should be at on a 7k tach so it will read low on an 8k tach.

Ah. I see. I didn't realize they had different redlines.

[kalib0y]

^ thats real racer status there brotha! :)

[highoutput]

Poop.......I dont have a coding plug, for sure. So! Looks like I need a new cluster.
Or maybe I'll get a monster Tach, and drive around like I have a spare tire mounted on my dash.

[kalib0y]

If you're running a M50/S50 then you need a coding plug from a 6 pot car. It should work with your M3 cluster. I have that setup too. But I don't know why your RPM is off. Maybe you need to double check the PN on the coding plug.

the tach still sweeps the same as if the 7k 325i tach was in there its just the printing of the numbers is shifted a bit so it reads higher

[Chris916]

Awesome thanks man. Honestly no i didnt do much searching lol. this thread popped up just as i started searching so i thought ip ask :P

[Matt-B]

i was just doing reading on the "coding plug" needed since i found out this weekend my tach on my 91 318is is also off with the m50. does anyone have a picture of this coding plug and where it goes for referance?

thanks

have you bothered to do a bit of looking around? searching? ;)

[Chris916]

i was just doing reading on the "coding plug" needed since i found out this weekend my tach on my 91 318is is also off with the m50. does anyone have a picture of this coding plug and where it goes for referance?

thanks

[Adrian_Visser]

It won't work 100% because the m3 tach redlines at 8k the needle will deflect to what it should be at on a 7k tach so it will read low on an 8k tach.

[RoadHazard]

yeah the older tachs dont have coding plugs. If I may add a question. Would an E30 M3 coding plug work if I have the e30 m3 cluster? Right now I am using the 325 plug with the M3 tach so my RPMs are about 500 off

If you're running a M50/S50 then you need a coding plug from a 6 pot car. It should work with your M3 cluster. I have that setup too. But I don't know why your RPM is off. Maybe you need to double check the PN on the coding plug.

[trackjunkie21]

Nope, it sends the signal for a 4 cylinder engine, you need an e28 m5/ e34 m5 one, but that takes a bit more "work"