M50 Electrics (Brian?)

Post Tue Sep 06, 2005 3:48 pm

Just in the process of making up the link loom to connect the M50 eng loom to the E30 C101 plug & I wonder if someone could just confirm that I've got it right so far plus answer a couple of questions for me.

Bear in mind that the E30 plug is from an 89' 325, the M50 eng is from a 91' E34 525 & the information about the functions came from this site.

Pin 1-E30 plug (Ign light) Bl wire to pin 25, Bl wire on E34 plug. Done.
Pin 2-E30 (Oil level) Gn / Y wire to pin 1, Bl / Wh wire on E34. Done.
Pin 3-E30 - no pin.
Pin 4-E30 (Water temp) Bn / P wire to pin 12, Bn / P wire on E34. Done.
Pin 5-E30 (Oil press) Bn / Gn wire to pin 23, Bn / Gn wire on E34. Done.
Pin 6-E30 (Ign feed from fuse 9 for the Hego Sensor) Gn / Wh wire. I presume it's just blanked off if no Cat is fitted or can it be used for something else?
Pin 7-E30 (Ign 12v+) two Gn wires (one thick, one thin). The thick one matches up with Pin 21 on the E34 plug. What does the thin one go to?
Pin 8-E30 (Fuel signal to instruments) Wh / Bk wire to pin 24, Wh / Bk wire on E34. Done.
Pin 9-E30 (Eng speed to instruments) Bk wire to pin 20, Bk wire on E34. Done.
Pin 10-E30 (Oil level) Bl wire to pin 2, Bl / Y wire on E34. Done.
Pin 11-E30 (Service light reset) Wh / Gn wire to pin 19, Wh / Gn wire on E34. Done.
Pin 12-E30 (Eng ECU check light) Gy wire. According to info from this site, this is supposed to match up to pin 8, Gy wire on the E34 plug. Pin 8 is blanked off on my E34 plug and there is no corresponding grey wire. Any ideas?
Pin 13-E30 (Fuel pump) Gn / P wire to pin 13, Gn / P wire on E34. Done.
Pin 14-E30 (Speed signal to instruments) Bk Wh wire to pin 14, Bk / Wh wire on E34. Done.
Pin 15-E30 (Start solenoid) Bk / Gn wire to pin 15, Bk / Gn wire on E34. Done.
Pin 16-E30 ( ? ) Wh / Bk wire. Does it go to anything or is it just blanked off?
Pin 17-E30 (no pin).
Pin 18-E30 (Starter) Bk / Y wire to pin 18, Bk / Y wire on E34. Done.
Pin 19-E30 (no pin)
Pin 20-E30 (12v+ to ABS) Bn wire to pin 3, R wire on E34. Done.
Earlier information suggested that this last one should be R / Y on the E30 plug & R / Wh on the E34 plug. I'm just hoping that this is one of those instances where BMW ran out of the correct colour wire

Pins 4 (Bk / Bl), 5 (Bk / Gy) & 6 (P / Gy) on the E34 plug are all Aircon so I can just blank them off, right?
Pin 7-E34 plug (drive away signal for OBC). Blank it off or does it need to be wired into the 9 button OBC in the E30?
Pin 11-E34 (Water temp) Bn / Y wire. What's this one for if the water temp is already taken care off by Pin 4 - E30 plug above?
Pin 10-E34 (Auto g/box) Bn / Bk wire. I've blanked this one as I have a manual.
Pins 16 (Wh / Y) & 17 (Wh / P) on the E34 plug are Rx Data (?). I've just blanked them off, right?
Pin 22-E34 - Gn / Wh wire. What is it?

Sorry it's such a long winded one but I reeeaaallly don't want to screw this up

All help greatly appreciated

Iain S

Post Tue Sep 06, 2005 4:24 pm

I I have just constructed a new loom for my race car so i may be able to help you.

First comment pin 20 ALL brown wires are earth. I think this should be a red/green supplying 12volt to the ABS.

Most (if not ALL ) sensor wires are Brown / another colour. e.g. Fuel level,engine temp, engine oil pressure.

There may be two water temperature switches on the car - one for the DME and other for instruments. (there are 2 sensors on my M3).

Karl

Post Tue Sep 06, 2005 9:42 pm

Right, just worked my way through all that lot.
Anything I don't mention below is exactly the same as my setup.

E30, pin7 - Connect both greens to E34,21

E30, pin12 - Are you saying you've got the grey wire in the body loom and not in the engine loom? That's the other way around from what I had. This is the "ECU is upset" warning light, and comes from (I think) pin 8 of the E34 ECU, and needs to go to a 12V warning lamp in the cluster,the other end of which goes to 12V+ with the ignition on. I used the orange "exclamation mark inside a cog" warning light position (auto gearbox warning).

E30, pin15 - This is the earth end of the two unloader relays in the fusebox. Goes to smallest ring terminal on the starter solenoid.

E30, pin16 - I had a white/black wire in the original E30 engine loom, but no corresponding socket in the E30 body socket. My E30 engine wiring diagrams don't show any other white/black or black/white wires anywhere, except the ones on 8 and 14, and I couldn't be bothered to trace it through the loom to see where it went. Definitely not needed. (Aircon idle speed??)

E30, pin 20 - Very strange brown is always earth. Couldnt be a discoloured red, could it?

E34 pins - 4,5,6. All aircon. I connected these to earth through three 1000 ohm resistors, just in case the ECU got spiked somehow.

E34, pin 7 - I connected this to earth via a resistor as wel. My M50 doesn't have an OBC, but there's no equivalent of this signal on an E30, is there?

E34, pin 11 - Not needed (used with 2 pin brown temp sensor on M50. Fit E30 brown sensor).

E34, pin 10 - I have no connector here, but mine was a manual donor.

E34, pins 16 and 17 - Data Rx and Tx. Not required.

E34, pin22 - This goes to pin 16 of the diagnostic socket, which links to pin 15 when the cover is in place. My notes aren't too clear here, but I'm fairly sure I connected this to pin 6 of the E30.

Hope all this helps a bit.

Post Tue Sep 06, 2005 10:50 pm

Brian you are truly the God of all the bright wiggly things that make bulbs glow & motors go whirr & stuff and I humbly prostrate myself in such Holy presence

Oh and I also owe you a

I'll get on to this ASAP & let you know how I got on.

Post Wed Sep 07, 2005 3:02 pm

.

Tried to label all the relevant parts but the image became too big to upload.
Plug on the left is the E30 Eng loom one to plug into C101 on the bulkhead.
Plug (socket?) on the right is for the E34 Eng loom to plug into.

E30, pin7 - Connect both greens to E34,21

As both of these greens are connected together at pin 7 on the E30 plug end, why connect them again further along the wire? I've just chopped this one short and sealed it off for now.

E30, pin12 - Are you saying you've got the grey wire in the body loom and not in the engine loom? That's the other way around from what I had. This is the "ECU is upset" warning light, and comes from (I think) pin 8 of the E34 ECU, and needs to go to a 12V warning lamp in the cluster,the other end of which goes to 12V+ with the ignition on. I used the orange "exclamation mark inside a cog" warning light position (auto gearbox warning).

The grey wire is actually in pin 12 of the cut-off bit of E30 engine loom that I'm using, and can be seen looking all lonely in the photo above. There is no corresponding grey wire in the E34 socket & pin 8 in the E34 socket is just blanked off. If I read your advice correctly, this should go to the instrument cluster?

E30, pin15 - This is the earth end of the two unloader relays in the fusebox. Goes to smallest ring terminal on the starter solenoid.

So this goes to the starter via pin 15 of the E34 socket?

E30, pin16 - I had a white/black wire in the original E30 engine loom, but no corresponding socket in the E30 body socket. My E30 engine wiring diagrams don't show any other white/black or black/white wires anywhere, except the ones on 8 and 14, and I couldn't be bothered to trace it through the loom to see where it went. Definitely not needed. (Aircon idle speed??)

Chopped this one short and blanked it off.

E30, pin 20 - Very strange brown is always earth. Couldnt be a discoloured red, could it?

Definately NOT a discoloured red and very, very brown. Working on the premise that the car loom side of C101 WILL be a red wire & there is a red wire from pin 3 of the the E34 socket, I've joined them together. I'm just going to have to cross my fingers on this one.

E34 pins - 4,5,6. All aircon. I connected these to earth through three 1000 ohm resistors, just in case the ECU got spiked somehow.

Do they have to be earthed? If there is no aircon fitted, provided the bare wire ends are suitably covered, could'nt they just be cut short?

E34, pin 7 - I connected this to earth via a resistor as wel. My M50 doesn't have an OBC, but there's no equivalent of this signal on an E30, is there?

As above.

E34, pin 11 - Not needed (used with 2 pin brown temp sensor on M50. Fit E30 brown sensor).

E34, pin 10 - I have no connector here, but mine was a manual donor.

E34, pins 16 and 17 - Data Rx and Tx. Not required.

All cut short & blanked.

E34, pin22 - This goes to pin 16 of the diagnostic socket, which links to pin 15 when the cover is in place. My notes aren't too clear here, but I'm fairly sure I connected this to pin 6 of the E30.

I've connected this up cos' I trust you :lol:

Thanks for your time on this Brian.

Post Wed Sep 07, 2005 8:56 pm

1/ If all the greens in the actual engine and body looms, rather than the link lead, end up connected together, that that will do

2/ If your E34 ECU doesn't support a malfunction warning light for some reason, then there's no p[oint in connecting the rest of the circuit.

3/ yes, pin 15 to pin 15.

4/ E34, pins 4,5,6,7. Probably OK just to chop, as I would expect there to be internal protection in the ECU. I just connected them each to earth via resistors to ensure that no voltage spikes are induced into them from other wires.

5/ E34 , pin 22. That's the one that my notes aren't clear on. I know I didn't connect it at first, as it didn't seem to go anywhere except the diagnostic socket. Then I found some notes I'd made that said that the diagnostic socket cap sghorts together pins 15 & 16, and pins 18 & 19 when it is fitted, so I connected it. It comes from a green/white switched ignition live on the E34, so the E30 green/white switched ignition live is the one for the job.