BMW Motronic Wiring

Simon · #1 29th November 2006, 18:34

I've recently made a start on sorting the wiring out and, in particular, patching the BMW Motronic wiring into the Marlin loom....

It all seems to make sense apart from one wire that according to the BMW wiring diagram goes to the on-board computer and is for 'ASC and Anti-Theft (DWA)'?? Since my donor didn't have ASC I'm assuming that this wire is for the engine immobiliser that is built into the dashboard computer unit. Does anyone happen to know wether this wire is needed and, if so, is it earthed, +12V or something else?

Even though starting the engine is still a good few months away it would be handy to know what to do with it!

Thanks

Simon

Rich · #2 30th November 2006, 07:51

What colour is that wire in question? Does it go through the C101 connector?

I had a quick look at the wiring diagrams from the 89 model. There is one from the Motronic Control Unit to the OBC. it is WT/BK on the engine side and Yl/WT on the car side. This is for the present fuel rate. B

But that goes via the instrument panel

Simon · #3 30th November 2006, 19:09

Sorry - but I forgot to mention that my donor car was a 525i (not 325i)...

The wire is black/violet and goes to ECU pin 38 and to pin 8 on the large engine plug. The wiring diagram shows it going to OBC pin #24.

Thanks in advance for any help you can give!

Rich · #4 1st December 2006, 09:21

Does the wiring digram state what the function of this connection is? If it is just information output eg, fuel consumption and you are not using the OBC then you can probably just insulate the wire and leave it.

However if the wire is information input in to the ECU it may be needed. For example the speed output from the speedo.
(may be good to check with a professional to make sure)