engine harness issue

#1

I am swapping an engine from a later model 325is into my 87 325is. Where the harness goes into the passenger compartment there are a few small connectors that I’m not sure where they go. I hooked up the DME and just a few inches from that connection is a 3 wire connector but it doesn’t match up to anything I have in the car. There are also two single wire connectors. I have a 3 wire connector in the vehicle, hanging near the “extra connector” but the wire colors are different. I will take pictures and attach them tomarrow. Anyone know what I am talking about or could someone check there car and take pictures??

#2

I have a early model. Some people say that early model and late model engine harnesses are not exactly the same. But of the differences I’ve read about, and JLevie is the guy to talk about it, I don’t recall anything similar to what you are describing.

That long caveat aside, once the cable comes thru the firewall into the passenger compartment, all it needs to connect to is the DME.

#3

You only need to worry about the three wire connector. It should be black. I believe this smaller harness is for the cluster (specifically the RPM input).

#4

I have another e30 that is untouched. I pulled down that cover to acess the DME and there is similar connectors. As Rob says the three wire one is the only important one (other than the DME), so I unplugged it and the car will not start and the check engine indicator will not illuminate. The only problem I have is that the harness I have in my track car is different and the wire colors are different. The weird thing is, is that the wire colors on the car I did the testing on are different on either side of the connector, so how do I figure it out? I will assume that the pin locations are the same and butt connect 1 to 1 2 to 2 and 3 to 3 and see if it starts. Anyone have anymore info?

#5

[attachment:1]C:\fakepath\dme connector e30.jpg[/attachment]

here is a picture… this is an 87 325i

#6

[quote=“E30KDG” post=56686][attachment:1]C:\fakepath\dme connector e30.jpg[/attachment]

here is a picture… this is an 87 325i[/quote]

The picture isn’t showing up for me. I have an '87 as well, and if memory serves me correctly, the wires do not match connector to connector. Next time I have a chance, I’ll snap a picture for you.

#7

There are ETM’s online that you can download for the different years. I would bet that you could trace the wires down with that and get it figured out.

EDIT

I found the site

http://wedophones.com/BMWManualsLead.htm

http://www.bmwtechinfo.com/etm/data/toc_cd2.pdf

#8

Well I went back to the shop tonight to check out those wires that were in question. I went to hook up the battery and check for power, ground, signal ect… Right when I did that I looked up and saw smoke coming from the fuse box under the hood on the driver’s side. NOT GOOD.

The car has not been started since I swapped in the new engine. It is from a 1990 325is, the car is a 1987 325is. There were a few things that were different (like the wires that I started this post about). But as far as power supply and such, I didn’t touch anything. The engine came from a running car (I started it before I did the swap), and I drove the doner car to the shop, so I know there isn’t a pre-existing short. Is there any major difference’s from a later model e30 harness? I can’t understand how there could be that big of a short? I have the grounds hooked up at the shock tower. I have all the power wires hooked up at the junction on the passenger side of the firewall. The DME is plug n play. The c101 is plug n play. Where could I have gone wrong? Any ideas? Is there a pin on the c101 I was supposed to switch and didn’t? I’m confused and upset I just cooked my fuse box and possibly my DME and I have a track event in a week!!

#9

I traced the “smoke” to a burnt wire from the c101 connector that goes through the fusebox into the car. It looks like c101 pin 20. Trying to find out what that wire is for? Ive seen a few documents saying pin 20 not used, and one saying it goes to the ABS. Any input? I’m having a hard time finding anything with the actual bmw manual on wedophones.com.

#10

I just google searched for BMW e30 etm or something like that and found some bummer forums talking about it. Do a search and you will find it.

I remember some wire swapping on the c101 for m20 to s14 swap so maybe it is a late to early thing.

#11

I found out that on an early model 325 that pin 20 on c101 on the harness is not used, but on the chasis side it is a ground. On the later model 325 harness that I am using, pin 20 on c101 is the power supply for the ABS control unit. So B+ and chasis ground met a c101 for about 30 seconds and burnt the ground wire completely, some of the power wire, the main relay, and possibly the DME. What I am going to do now is cut along the engine harness to expose the damage; somewhere there is a splice on that power wire so I’m not sure yet how much damage is done.

#12

I’m putting a mystery engine in my 1990. I have attached pictures of the C101 and diagnostic plugs for the mystery (right) and 1990 (left) M20 wiring harnesses. I had smoke from the driver side when I hooked up the battery as well, but couldn’t find any burnt wires or pins (the sparks were a clue, and I disconnected the terminal right away). I’m trying to figure out 1) what year the mystery motor is and 2) what terminals I need to switch on the car side of the C101 to make everything happy.

#13

Oh by the way, I have an undamaged wiring harness from the 1990 motor, if you end up needing it (and if I can figure out my swap without using it).

#14

When using an early harness in a late production car, the secret for the C101 problem is to clip the wire the wire that goes to pin 20. I clip it on the body side so that I can replace the harness, if necessary, w/o having to remember to “adjust” C101.

#15

Maybe this is how we definitively tell an early harness from a late harness. By early and late I mean harnesses that have the same round multi fuel injection connector vs. the individual connectors as Robert Patton mentioned in an adjacent thread.

As I understand this thread, I can safely put an late harness into an early car, but not vice versa. Agree?

#16

Maybe this is how we definitively tell an early harness from a late harness. By early and late I mean harnesses that have the same round multi fuel injection connector vs. the individual connectors as Robert Patton mentioned in an adjacent thread.

As I understand this thread, I can safely put an late harness into an early car, but not vice versa. Agree?[/quote]
A late (from 9/87 on) harness in an early car causes smoke unless you clip the wire going to pin 20 of C101 on the body side. As mentioned, there are two late variants with the difference being the style of injector rails. As far as I know there are no other differences in the two late variants.