Blue Plug on cluster wiring help

[pianist]

As above, I am trying to wire in tachometer and econometer into my instrument cluster as my car was 316 carb and didn’t have such privileges of showing rpm and fuel consumption but it was good at time keeping with oversized clock in the dash.

I have found this on wiki: http://www.e30zone.net/e30zonewiki/index.php/C101

So as I understand it should go something like this:

I need wire from c101 plug pin-8 to ”aBlue Plug”a pin-11 on cluster for econometer

and c101 plug pin-9 to ”aBlue Plug”a pin-7 for tacho.

Now the thing with my ”aBlue Plug”a is that it seems pin-7 and 11 together with 3rd wire (looks red or brown) are routed back under the Glove Box where ECU sits (should have mentioned that my bmw is LHD) with 3-pin plug on the end that looks a bit like Molex connector in PC but smaller.

I said ”athey seem to be routed”a there because I can’t physically see wires routing back to plug since they end up in wiring loom and I’m bad with colours (exept for the black wire that goes from pin-7), but if I use Multimeter I get continuity between pins 7 ,11 and that 3pin ”aMolex”a plug contacts 1 and 3 I think.

So can I just route this cable back to c101 plug and connect it to corresponding pins?

Just need this clearing before I blow something up lol

Thanks

[Grrrmachine]

If it "was" a 316 carb, what engine have you converted to? The "molex" socket that you've found near the ECU is called the C104, and yes, it contains the wires you need for your instruments. Data is on the ECU pinouts page:

http://www.e30zone.net/e30zonewiki/inde ... s#Jetronic

And this is taken from the Wiki page on Converting to Motronic 1.3:

"What wiring does need doing is for instrumental purposes only and is easiest to carry out on the ECU plug end. There are two wires you need to cut on the ECU plug and then connect to the C104 plug which will now be unconnected following the removal of the old loom. The easiest thing to do is cut the matching plug from the old loom and plug it into the loose plug in the car. Then you need to connect pin #1 (Blk/Blu) on the C104 to pin #6 (Blk) on the ECU, the second connection to make is to connect C104 pin #3 (Wht) to ECU pin #32 (Wht/Blk), C104 pin #2 is not used. "

[pianist]

I'm in process of converting it to M30 but I have diagram of pinouts of Motronic ecu and I think them signal whires end up in c101 plug and since I have bought bunch of conntacts for it when wiring fuel pump in and stuff I might just wire it up using c101 plug.

Thanks for comfirming what them wires are for though, now I can go and use them with no fear in my mind lol.

daz

[Grrrmachine]

yes, it doesn't matter whether you run from the cluster to the C101, or cluster straight to the ECU; the result is the same.

[pianist]

found this on revlimited forum (c104 plug):

yellow purple wire connect to pin 8 on c101
green wire connect directly to the positive terminal on the coil
black wire connect to pin 9 on the c101

That green wire he mensions is pin-2 on c104 plug but why would you connect it to the coil I have no clue, in wiki it is not mentioned so I better leave it isolated?

[pianist]

Please ignore my last post as I found what all the pins on c104 plug do:

Info from: http://spece30.com/forum/41-electrical- ... -and-i-mot

For future reference:

c104 plug from 1986 325e body harness has three wires:
1- black wire-engine speed
2-green wire-OBC fuel cut function
3-yellow/white wire-fuel rate
On the 89 I harness, splice or connect the following wires to the ones on the c104
Pin 3 from c104 to pin 8 on the c101 of the 89(yellow/white or white/white wire)
Pin 2 from c104, run a wire directly to the + terminal on the coil (green wire)
Pin 1 from c104 to pin 9 on the c101(black wire)

Since newer ecu's have fuel controll on anyway I don't need this wire to be used