Some wiring help please

Sun Sep 20, 2015 8:54 pm

hi, I'm currently installing a complete engine and efi from an 85' 1.8 l-jetronic and have come across a real issue.

Although this awesome website has some brilliant info on the m10 l-jet I can't find out what the little plug from the ecu loom is needed for. So far all I know is it's called a c104 and that it has something todo with the instrument gauges.
If somebody knows where the 3 wires go, one black, one green and the other yellow I would appreciate it so much.

Mon Sep 21, 2015 6:53 am

Thanks for the reply, sorry for the lack of detail. I'm actually installing it into an e10 so very little electrics need wiring in.
So far I have a spark using the e30's electric ignition and can get the fuel pump to prime but only if I connect the green wire from the c104 to an ignition live?

The engines turning over, I can see fuel being pumped to the injectors and I have a spark but no start!

Mon Sep 21, 2015 8:56 am

I have various wiring diagrams which have helped me get this far but they are all very vague when it comes to the c104 connector.
So with the green c104 wire connected to ignition live when I switch the ignition on I can hear the fuel pump prime for about 3 secs along with the fuel pump relay ticking for about the same time. If I understand what your saying then I should unhook the green c104 wire as I shouldn't be hearing the fuel pump prime every time I switch the ignition on?
Without the green wire connected I have never heard the fuel pump prime.

Mon Sep 21, 2015 9:02 am

I can't say that I've checked if the injectors are firing so will give that a try thanks.

I'm not sure if this could cause a problem but I have used the original e10 wiring loom and just piggybacked the e30's so the alternator and starter motor connect only from the e10 loom and not the e30 one. That includes the black and yellow wire that hooks up to a terminal on the starter motor. I'm starting to think this wire might want to be hooked up for some reason?

Tue Sep 22, 2015 6:26 pm

Turns out I was being a complete moron, I had my fuel lines mixed up

switched them around and after a couple of cranks she fired up!
Thanks for the link, book marked for future reference.

I love this forum and its info so much it makes me want an e30 as my next car for sure.