wiring problem and unloader relay

[Mr Mpower]

Hi, i've dropped a m52 engine in my 1983 318i e30, and it don't want start, but that's not the the reason for this post..

at first i've made the wiring like this

C101 square ……………x20 round………………
1 blue…………………………………25 blue……………………alternator
4 brown/violet………………12 brown/violet……temp gauge
6 green/yellow………………15 black/green………..starter
7 green/violet……………………13 green/violet………fuel pump
8 black/yellow…………….18 black/yellow……….cranck
9 black……………………………20 black……………………rpm tach?
10 green…………………………...21 green………………….dmw power
16 brown/green...............23 browm/green……oil pressure
17 white/blue...................19 white/green....service interval reset

but looking a bit more, it seems like pin 6 c101 to pin 15 x20 is wrong, the problem is at the c101 side in europe we don't need to use the pin 6 c101, that's ok.
but in the x20 side i still having the pin 15..wihout any pin to splice in the c101 side..where i need to plug it?

maybe like this?
c101 side.........................x20 side
pin 8 black/yellow .....to....x20 pin 18 black/yellow and x20 pin 15 black/green

[Thujalvi]

Have you determined that the unloader circuit is not working? What happens when you try to start the engine, do the headlights, headunit etc get switched off? The way the unloader relays work, is in normal operation they are grounded through the starter, but when it cranks, the coils are energized (this from bmw etm), so if you want to troubleshoot the problem, try grounding C101 pin 6.

[Mr Mpower]

maybe my explain isn't clear.
this is a euro car, first with a 1983 m10b18 inside and now with a m52b28.
euro cars don't use pin 6 at c101 (car side) because we don't have any pin for that in our x20 connector.

the problem is with my pin 15 in my x20 connector (engine side)...i know is for the unloader relay but it don't have any pin in the c101 connector (car side) to match it..

for that, i answer where to plug the pin 15 x20 (black/green)..maybe i need to unplug from pin 15x20 (engine side) and splice with pin 18x20 (engine side)?

[Thujalvi]

No pin 6 in the c101? Do you still have relays k5 and k7? (I'll assume they are the same on early cars as they are on late ones.) As for connecting x20 pins 15 and 18, I'd expect that to prevent the starter from working, as it'd essentially short circuits the coils in the starter, though if you want, feel free to try it anyway.

But if there's no unloader circuitry in the car, the x20.15 isn't doing anything and the fault is elsewhere.

[Mr Mpower]

No pin 6 in the c101? Do you still have relays k5 and k7? (I'll assume they are the same on early cars as they are on late ones.) As for connecting x20 pins 15 and 18, I'd expect that to prevent the starter from working, as it'd essentially short circuits the coils in the starter, though if you want, feel free to try it anyway.

But if there's no unloader circuitry in the car, the x20.15 isn't doing anything and the fault is elsewhere.

i have pin 6 in my c101 but in the x20 (euro harness) we don't have pin 22 to plug it..
because of that, i have pin 6 but i don't need it for nothing..at first i've plug into pin 15 x20 ..but that's wrong true?