c101 and x20 wire diagram (e30 M50 adapter)

[m_dudey]

i have a 89 325i coupe, build date 10/88. Do I use the 88 325i ETM or the 89 325 ETM?

[bimerok]

i have a 89 325i coupe, build date 10/88. Do i use the 88 325i etm or the 89 325 etm?

89

[EtaSport]

check your colors against both, I have found differences in some. The pins should be the same but you may find colors dont match up.

[m_dudey]

EtaSport,

I have an early model 89 325i and the engine wiring harness from a 93 325i manual. I looked into the ETM for both wiring harnesses and I have confirmed the colors and the function. I even have a spreadsheet where I mapped out each pin, color, it's function, and what page to find it on in the ETM.

After doing so, I matched up the functions of the e30 harness and the e36 harness and what I came up with was very similar to your diagram in your post#35, shown here.

http://r3vlimited.com/board/showpost.php?p=542432&postcount=35

I don't have pin 20 because mine is an early model of the 89 325i, build date 10/88.

Then I saw your post# 48 shown here

http://r3vlimited.com/board/showpost.php?p=546954&postcount=48

And it's an update to what you had before. I can see why you made some of the changes. And I have an idea on how to hook up the oil level sensor correctly.

My question is do you have an updated or final working diagram, or is the one in post #48 the most updated one?

[EtaSport]

I believe thats all I had, its been quite awhile. I did find that I wired up my low oil pressure sensor wrong. There were two brown/gray wires in my loom on the e36 side. If you are uncertain which one to wire to pin 5 of the c101, just temporarily splice the wire to check. Mine is finally working now, just have to fix my friends' as I missed his too.

[Jason89i]

check your colors against both, I have found differences in some. The pins should be the same but you may find colors dont match up.

........I have confirmed the colors and the function. I even have a spreadsheet where I mapped out each pin, color, it's function, and what page to find it on in the ETM.

Just as a side note....

Wiring colors can change color at the c101. The wiring color may be one color on the engine side of the c101 BUT be a different color on the chassis side. For instance.... on an e30 m3, the oil pressure signal is BRN/GRN on the engine side, but BLK/BRN on the chassis side.

Cheers, Jason

[tonton]

Ok on an 88 is there much diff to the 89 and 90 or should this pin to pin diag. work

88 325 C101 to 94 M50 x20
1-25
2-1
3-X
4-12
5-23
6-22
7-21
8-24
9-20
10-2
11-7
12-8
13-13
14-14
15-15
16-19
17-X
18-18
19-X
20-3

You guys see any problems?

i see, i don´t have any wire in x20 pin 8 (gray)

so what goes c101 pin12?

have anyone working diagram for x20 e34 m50 vanos (9/92->) - e30 325 (88->)

[m_dudey]

i see, i don´t have any wire in x20 pin 8 (gray)

so what goes c101 pin12?

have anyone working diagram for x20 e34 m50 vanos (9/92->) - e30 325 (88->)

might want to check out this thread too.

http://r3vlimited.com/board/showthread.php?t=130715

[OrganicMechanic]

save the headaches.

READ THIS

[jogfrogjog]

anyone have a pic of the back of the cluster or the pin out for the green connector?

[Frog]

Can't find anything for early 318i. ugh!

[nando]

I've read this entire thread and done my own research, this is what I've come up with:

http://www.megasquirt.325ix.com/MS_to_Motronic/C101%20to%20X20.html

What gets really confusing is what people are doing with C101 #6 (O2 relay on the E30) and C101 #20 (ABS relay, powered from some random place, apparently).

If I'm not mistaken, the E36 harness powers the O2 relay directly from the main relay, and has no connection to the X20 at all. The E30 harness powers the O2 relay by connecting C101 #6 to fuse 9.

So what then, is the purpose of connecting C101 #6 to anything? I've seen a few suggest X20 #22, which goes to the E36 fuse box (fuse 25 or something), which doesn't exist on the E30, making it a dead end. As far as I'm concerned, there's no requirement to connect C101 #6 to anything on the E36 harness side.

Then we get to the late model ABS relay, where there is just as much confusion. It just needs switched power, and not a whole lot - the pump itself is connected directly to the battery.

I think the simplest way is to connect C101 #6 to C101 #20. That will power the ABS relay through fuse #9. If you look at the E30 harness, it basically does the same thing, only it doesn't go through fuse #9. I think the power requirements for tripping a relay are small enough that the 15a fuse at #9 should be enough.

Does any of this make sense? It's sort of unbeleivable that 10 years into swapping M50s and there's nothing concise about the C101/X20. I know there are harness differences on E30s but they're not that significant. There's more bad information on the web than useful.

[FredK]

I'm pretty sure that x20 pin 22 passes switched power to the diagnostic connector (X6002 pin 16), and if it's not connected, a code reader won't work. I think I thought the same thing at one time and did not make the C101-6 to x20-22 connection.

But yeah, you're right, C101 pin 6 is just a switched hot and can be used to power the ABS, among other things.

[nando]

that it does, so by connecting it to X20 #22 you're really just powering the diagnostics port (which I don't care about), not the O2 relay which I think is where the confusion is coming from.

[Mr.SWISS]

On OBD2 temp sensor pigtail which one goes to the cluster on the X20?

Is it the brown violet or the brown yellow? Trying to figure out which goes to the E30 single wire pigtail I have on the E30 sender. And do the O2's get power within the harness? Trying to make sure I covered all my bases this OBD2 is the same for the most part just a few loose ends lol.