Where do i find wiring diagrams for engine plugs??

[iamsam]

I searched and read threads all morning (from 8:15am till 1:00pm) and i still need clarification on how to adapt the wiring plug on the M50 engine to the wiring plug on the E30 chassis.

I saw the website http://www.wedophones.com/BMWManualsLead.htm mentioned over and over again, but either i am missing something or there is a problem. I could not find an actual wiring diagram of an engine plug (C101 or x20) that told me which pin does what on that site. I only found a diagram of the diagnostic plug, and only a drawing of the engine plug, no info on it.

people have uploaded different diagrams which look helpful, but i have read that almost each model year is different, so i am afraid that any i see may not be the right diagram.

So i want a couple of things clarified in the most general sense:

1. To do an M50 swap, as one of the steps you need to adapt the M50 engine-side plug to the E30 chassis-side plug, and to do it, you need to match correct wire functions together using two wiring schematics, correct?
2. Where do i find these wiring schematics to do this for both the E30 and the M50?

Thanks so much.

[etxxz]

the diagrams have numbers in every junction you see. they mean a pin for a particular plug... for example a juntion may say 14 C101...that's pin 14 for your C101 plug. sometimes they don't have the plug next to every number.. in this case the plug carries on to all the numbers in parralel... same for the m50 diagram ex on thatone you can use the search button and find all the X20 locations.

you need to search for the wiring schematics, but the best way is to get diagrams for your particular cars and match functions yourself. its not hard. start C101 goes to start X20, alternator C101 goes to alternator X20...that is your adapter from C101 to X20 basically.

search more and good luck my friend. i spent months researching how to wire my obdII setup..

[iamsam]

the diagrams have numbers in every junction you see. they mean a pin for a particular plug... for example a juntion may say 14 C101...that's pin 14 for your C101 plug. sometimes they don't have the plug next to every number.. in this case the plug carries on to all the numbers in parralel... same for the m50 diagram ex on thatone you can use the search button and find all the X20 locations.

you need to search for the wiring schematics, but the best way is to get diagrams for your particular cars and match functions yourself. its not hard. start C101 goes to start X20, alternator C101 goes to alternator X20...that is your adapter from C101 to X20 basically.

search more and good luck my friend. i spent months researching how to wire my obdII setup..

thanks so much for your help. I am starting to understand all of this slowly...

[iamsam]

OK i am still really confused. I am looking through the 140 page wiring manual for the 1990 325, and i guess i don't know how to figure out which pin on the C101 plug has which function.

Here is a screenshot of a page of the diagram, with the pin number 18 and C101 circled. How do i read this diagram to find out what function pin 18 has on the C101 plug?

[etxxz]

okay... you picked a terrible pin.

look at for example under "charging" for both wiring diagrams... that is the alternator (or generator for the e36). Notice how pin 1 of the C101 is the alternator. then head to the m50 diagram and look at pin 25. same functions. So, your adapter will do pin 1 C101 to pin 25 X20. you know AKG can sell you a working adapter btw....

search on here for 'wiring kamasutra'.. open that thread and make a similar spreadsheet with your wiring diagrams. good luck man.

[gregslow318i]

if you need me to make you one pm me I have made about 15 of them now
saves a lot of headache

[iamsam]

okay... you picked a terrible pin.

look at for example under "charging" for both wiring diagrams... that is the alternator (or generator for the e36). Notice how pin 1 of the C101 is the alternator. then head to the m50 diagram and look at pin 25. same functions. So, your adapter will do pin 1 C101 to pin 25 X20. you know AKG can sell you a working adapter btw....

search on here for 'wiring kamasutra'.. open that thread and make a similar spreadsheet with your wiring diagrams. good luck man.

ok, still confused. So you are saying that the fact that pin 1 of C101 is on the charge page of the pdf, that it means that the pin is the alternator? or is the pin function based on where exactly it is on the diagram?

[etxxz]

its a signal to the ecu or your dashboard or your ignition column... forget the function. think of it as it goes from alternator to dme/dash via X20 across adapter c101 to original e30 body harness.

the 'engine' harnesses of these cars are basically isolated with their own dme.... i think its good to learn how to do this. its very valuable and not just for car things, but it takes a lot of time ooor you can buy an adapter... i can make you one as well.

[iamsam]

its a signal to the ecu or your dashboard or your ignition column... forget the function. think of it as it goes from alternator to dme/dash via X20 across adapter c101 to original e30 body harness.

the 'engine' harnesses of these cars are basically isolated with their own dme.... i think its good to learn how to do this. its very valuable and not just for car things, but it takes a lot of time ooor you can buy an adapter... i can make you one as well.

Thank you so much for all of your help. I am going to digest this knowledge and go ahead with the swap, since wiring comes last anyway, and see how i do. It can't be that bad, i don't consider myself unintelligent...;)