Are early square C101 and late round C101 pins the same?

[alistairolsen]

I have an early (84) E30 into which I'm fitting a 94 M60. I have the M60 loom with the X20 connector, and a mating connector and the chassis loom has the early style square C101.


I either need to:


swap the chassis plug to the X20 so the engine can be plugged in directly (neatest and least possible fault points),



or find a pair of round C101 plugs and swap the chassis plug from round to square, then make the usual C101 to X20 adaptor loom (plugs are easy to find),



or find the mating square C101 plug and make a converter from that to X20 (leaves the chassis loom unmodified).


So with that in mind, does anyone know:


Are the actual metal pins common between some or all of the plugs, or will I need to repin all the wires?


Can you still buy the square engine side C101 plug and if so whats the PN? Looking here: http://www.realoem.com/bmw/enUS/show...diagId=12_1512


The housing may be 12521273189?


Thanks

[nando]

I think they are the same - they are in the ETK somewhere, but it can be a pain to find pins sometimes.

Unfortunately, the square C101 plug has been NLA for a lonnnng time. Like 20+ years.. you're best off just converting it to a round C101, or cut one off an early engine harness and re-pin it.

[Jaxx_]

From E30Zone Wiki:

https://www.e30zone.net/e30wiki/index.php?title=C101

Late Round:
Pin Colour Function To
1 Blue Charge light pin 16 blue plug inst cluster
2 Green/Yellow Static oil level Pin 16 check panel
3
4 Brown/Purple Temp gauge pin 26 blue plug inst cluster
5 Brown/Green Oil Pressure light pin 18 blue plug inst cluster
6 Green/White Oxygen sensor relay Fuse 9
7 Green Switched power Ignition switch
8 White/Black Fuel rate input pin 11 blue plug inst cluster
9 Black Engine speed input pin 7 blue plug inst cluster
10 Blue Dynamic Oil level pin 20 Check Panel
11 White/Green Reset service lights pin 22 blue plug inst cluster
12 Grey Check Engine indicator Check Light
13 Green/Purple fuel pump relay fuse 11
14 Black/White Speed signal out to ECU pin 10 white plug inst cluster
15 Black/Green Unloader relay pin 1 blue plug inst cluster
16 White/Black Diagnostic connector Diagnostic plug pin 6
17
18 Black/Yellow Start Ignition switch
19
20 Red/Yellow ABS power ABS control module

EARLY / SQUARE:

Pin Colour Function To
1 Blue Charge light pin 16 blue plug inst cluster
2 Green/Yellow Static oil level Pin 16 check panel
3
4 Brown Temp gauge pin 26 blue plug inst cluster
5
6 Green/White Oxygen sensor relay Fuse 9
7 Green/Purple fuel pump relay fuse 11
8 White/Black Start Ignition Switch
9
10 Live power from ignition unfused
11
12
13
14
15 Black/Green Unloader relay pin 1 blue plug inst cluster
16 Brown/Green Oil Pressure light pin 18 blue plug inst cluster
17 White/Green Reset service lights pin 22 blue plug inst cluster
18
19

[reelizmpro]

I think some pins are larger than others on the early connector.

[alistairolsen]

@nando, Thanks for that, its a shame that the connector is NLA, but good to confirm.

@Jaxx_ ,I'd found the wiki page, but nothing on there about repinning and I'd prefer not to cut/solder the chassis loom if I can avoid it.

@reelizmpro, I checked this morning and you're right.

[alistairolsen]

Ok, so for reference, here is what I have:

1) cover over the connector



2) Connector itself mounted to the fusebox



3)Connector pins showing different sizes but all male bullet nose style. 8 pins in total. This is different to the diagram shown on the E30zone guide as there are two rows with two large pins in each in the centre. Here is a listing for the same style plug https://www.r3vlimited.com/board/sho...d.php?t=147610



4) wiring tails



White
Brown
Green
Purple
2x yellow and something
I'll check the rest this evening.

5) Mounting lugs on the fusebox



From a search online, the E30 round C101 connector seems to be mounted on the other side of the fusebox



Which should clear the engine:



So it probably makes sense to upgrade to the newer style plug which is still available and allows me to incorporate the other pins which I need to take from the C104. On the other hand, a mating connector to this plug is neat and doesnt mess with the car and would allow me to mount the X20 in the normal C101 location.

[Jaxx_]

@Jaxx_ ,I'd found the wiki page, but nothing on there about repinning and I'd prefer not to cut/solder the chassis loom if I can avoid it.

Based on the information in the wiki page, I thought it was clear you couldn't do a simple repin, regardless of pin size/shape.

If you are removing the engine harness, why not cut it up and have an adapter harness to your desired X20 connector? Alternatively, you can modify the engine harness for the M60 to have the engine side square C101 connector.

What do you plan to keep on the M60 to car side? Are you implementing features like the oil level sensor? MPG gauge?

You only "need" 4 wires from the C101 for the car to run: alt, run, start, and fuel pump.


Edit: Just as a side note, I'm a big proponent of crimping rather than soldering for the engine bay and body harness. Vibration can wreak havoc on stiff and brittle solder joints, regardless of how well they were done.

[Jean]

Best way to tackle this is to download the ETMS for your car and donor harness ... and match the wires by function . Also , you’ll need to run a couple extra wires from the engine m6x harness that don’t exist on the m10 square connector .