Love your C101!!!

[FredK]

Since you have an 87, your system is unloaded through pin 18 (ignition). You don't have to ground out anything.

[haaken675]

https://youtu.be/euxmWXAJg9U

I appreciate the link. I have watched this before a while ago, and it's definitely helpful. My big question is what to do about the apparent lack of an unloader relay (black/green wire). I think I can simply ground out t3eh circuit to eliminate potentially?

[raj]

I definitely do not have anything in pin 15, and there are no black/green wires at all...Anyone have a solution?

I had an issue where I replaced my starter with a 3 terminal unit. Prior to 8/87 E30s had 2 starter terminals, combining the unloading relays with the key start (combining 8mm and 10mm terminal to one). So 8mm terminal on the starter, which is usually for the unloader, can be left empty.

I think pin 15 can be safely eliminated in your circumstance. In my case I cut it out.

[pazi88]

https://youtu.be/euxmWXAJg9U

[haaken675]

Ok, so when I went to wire my c101 connector to my e34 harness I ran into trouble because most user made diagrams did not match my wiring scheme. This thread got me through it though as OP had similar wire colors as me. I wanted to post my wire colors in hopes of helping someone else out:

Wire color on 'car' side of c101 for a 8/90 318is:

1 empty
2 blue/yellow
3 empty
4 brown/violet
5 black/brown
6 green/yellow
7 green
8 empty
9 empty
10 violet/green
11 white/blue
12 brown/black
13 violet/red
14 empty
15 empty
16 white/black
17 empty
18 black/yellow
19 empty
20 brown

I know this post is old, but i am coming up with the same issue and it looks like this guy never got any response...I have a 1987 325is with the round c101, and my c101 wiring is exactly pretty close to as described above. I am trying to match up the wires to my m52b28 harness and this is throwing me off as mine doesn't match any of the diagrams I have seen. I definitely do not have anything in pin 15, and there are no black/green wires at all...Anyone have a solution?

[vaughnbannister]

So i ave a question that might be C101 related.

I swapped my car over 2 years ago and everything works perfectly fine BUT the check panel. Is there maybe something that is not wired correctly or something i missed for this? the seatbelt light works that is right next to it but noting else.

[nando]

also I do not believe the wiring chart at the top is correct. No way pins 14 and 15 are empty.. all late E30s have a pin 14 and 15 (VSS and unloader relay). same for pins 8 and 9 - unless your 318is doesn't have a tachometer or an econometer.

I'd be willing to bet pin 20 is actually red, but the wire cover has just turned brown due to age - because brown is typically only for grounds, and pin 20 is definitely not a ground.

[nando]

that is a well known wiring difference. the 89 doesn't have any pin 20 because it doesn't have an airbag, which is why you didn't have a problem. airbag cars have different ABS wiring - the relay is on the ABS unit, and pin 20 is the power signal that trips the relay. When you plugged that harness into your '87, it connected 12v to ground and nearly caused a fire.

[e30_325es]

Bump for new pin 20 info. I just installed a 90 I engine and harness into an 87 eta chassis. Turned the key and smoke started coming from the main relay wires. Found the ABS power wire that runs out of the main relay to pin 20 is what fried. The body side has an unused ground at pin 20, and shorted out the wire. I cut the wire for now, and no more smoke was released. Eventually I will wire in a bypass for the ABS. On the 87 chassis, the ABS gets its power out of the over voltage relay in the fuse box.

The strange thing about this is that I have swapped an 89 harness into an 86 chassis with no ABS issues, so I never thought to check for this.

[benz-tech]

If the mods wont sticky this then I'll just have to bump it with some accolades.
This page helped me re-pin my entire C101in about 2 hours, with each pin verified. BIG props to the op. The explanation of what each circtuit does makes a big difference too.

Id like to add that pin 14 is used on the later E30's for the VSS signal from the cluster. An absolute must for an OBDII swap, and possibly needed for some OBDI.

[barry]

Well done by a class act. Thank you

[18rabbit]

Ok, so when I went to wire my c101 connector to my e34 harness I ran into trouble because most user made diagrams did not match my wiring scheme. This thread got me through it though as OP had similar wire colors as me. I wanted to post my wire colors in hopes of helping someone else out:

Wire color on 'car' side of c101 for a 8/90 318is:

1 empty
2 blue/yellow
3 empty
4 brown/violet
5 black/brown
6 green/yellow
7 green
8 empty
9 empty
10 violet/green
11 white/blue
12 brown/black
13 violet/red
14 empty
15 empty
16 white/black
17 empty
18 black/yellow
19 empty
20 brown

[ck_taft325is]

Sticky or ban.

[amcink]

Subacribe

[Ether-D]

I just want to say thanks OP. Linking this to my build for reference.