When doing engine swaps, yes, you track down what each pin is, and then start moving wires to where they need to be.
Sometimes you have to go through multiple connectors, at which point, yeah, it becomes easier to
wire around the discrepancy rather than chase it through various routing. You need to be
careful to confirm that no- one gets kicked off the island when you do that, though, as often a signal's
routed differently because it's also going to a third destination as it makes that roundabout trip.

What gets involved is that you may then end up having to change other components, and re- pinning their connectors
as well. Have you confirmed that the N42 dash is the same as the M54?
With the E46, BMW was on their way to making discrete electronic assemblies interchangable, but had not
yet fully succeeded.

For example, can you find an oil level input on the dash connectors? Frustratingly, the labels aren't
always explanatory or consistent- often, you're left tracing out the wires on the corresponding diagrams...

Repinning the connectors isn't too hard- you just need to decide on which side you want to do it
(do you make your body harnesses M54 pinning (recommended) or do you make an 'adaptor harness'
to stick an M54 into an N42 body)

You're on the right track, keep at it!
t

 

Thank you, i've tried to be thorough while preparing for the swap, but didn't expect to stumble upon issues like this. It was never supposed to go smoothly, this is a learning experience for me.
I've managed to decode a bit more of the number soup that is the WDS: Apparently, both fuse 29 and fuse 30 of the N42 X6021 port 1 and the M54 X6011 port 2 end up at the S2 Ignition switch, they're both getting power at the same time. Thus i've decided simply move the M54 X6011 port 2 into the first port in the X6021 connector. The only difference is that Fuse 29 is 7.5 amps, and Fuse 30 is 5 Amps. If it doesn't work, replacing Fuse 30 with a 7.5 amp one should do the trick.
Downstream, it just connects to one of the DME connectors, as does the M54 X6021 port 2, so that should be fully compatible. The only differences now are the connectors going to the instrument panel. I couldn't find specific differences in the WDS, so i'll just try to run the engine without these two connectors and see what happens. I'll update as soon as the rest of my parts arrive.

 

Update!
I soldered the M54's X6011 pin 2 to the X6021 pin 1 on the car.
Started the engine for the first time today and all seems well. Fuse 30 did not blow and i don't have any warning lights.
I did notice that the battery light on the dash that is supposed to indicate a failing alternator turns off while i'm still in key position 2 (before starting the engine). that indicates to me that the instrument panel does not know if the alternator is charging or not, as it is only supposed to turn off once the battery is being charged. That is probably due to the M54's X6011 pin 4 not being connected. The oil light seems to work however, and disappeared after the engine started. A probably unrelated problem is that the Secondary air pump does not turn on.
I hope this info is gonna be able to help out the 1 or 2 people that are crazy enough to do this swap.
Regarding wiring info, i can recommend bmwteka.com aswell as the "WDS for Android Free" app, those two helped me figure this out.

 

But on x6011 the 2 port are empty, jos did goi connect?

 

Started this exact project just over 2 weeks ago and your post is really helping me! Apparently the guy I bought the engine from, provided the incorrect transmission harness so now I'm just waiting for the correct one to arrive.

Did you do anything else than changing pin 2 from X6011 to pin 1 on X6021?
I have SAP delete, so the air pump not turning on, wont be an issue for me.

Is your AC, headlights, heating etc. all working?

Thank you!

 

I didn't do anything electrically except changing the two pins you mentioned. I didn't touch any fuses, relays or other pins, and the engine is still running just fine.
The sap pump fixed itself and everything else is working, except the AC compressor, which you will have to manually wire to X6011 pin 8, which is where the N42 had the compressor switch. I haven't done that yet, but I'm pretty sure if you do that, it'll work just fine.
Remember you need to bring the wire all the way from the compressor into the DME box yourself, as i believe the M54 engine harness does not have a plug for the compressor (at least mine didn't).
Good luck with your project, it's nice to hear this post is actually helping people.

 

I'm so glad to hear that! Was just about to pay 950€ to get this car shipped to an expert so he could sort out all the wiring. Now that I discovered, I had the wrong harness it all makes a lot more sense.

Will definitely be wiring the AC compressor so that works, but thats the smallest issue at the moment.

I really appreciate this post. Don't think anyone else in Denmark has done this exact swap so I was really exited when I discovered your post.

Thank you so much

 

im a bit late on this post but im about to do the same with my e46 318i could I may have your Facebook if I need any help with the swap im from Denmark too

 

One of the fantastic things about the E46 is that the wiring usually isn't all that complicated.
Another thing i did, which you probably already know though, is get the DME of the new engine and the EWS module/immobilizer of the old car coded together, so that the immobilizer actually lets the key start the engine. It shouldn't be too expensive, i found someone on ebay who i sent the car's EWS module, the new engine's DME and the car's key, and when i got them back it all worked first try. If you don't do that, the engine will not start.

 

Yes I was aware of that.
I purchased a DME from Digital Tuning and got EWS delete so this wouldnt be an issue.

But thanks for the heads up

 

Then you should be good to go

 

The guy I was about to buy the transmission wiring harness from, apparently had the wrong one. Do you by any chance have pictures of the harness that goes down to the transmission and 02 sensors? Or can you confirm, its supposed to look exactly like this? I found these pictures online and those connectors seem to match my other harnesses perfectly.

 

Sadly i didn't take any pictures, but as far as i remember, on the manual transmission there was only one plug for the reverse lights switch, and then one each for the two O2 sensors at the bottom of the header+cat combo. The pictures you sent could work, as it has those, but it also has two more plugs which i can't identify. You'd need to check if your engine has anywhere to plug them

 

The pictures I sent would match my engine wiring harness perfectly.
The plug within the red circle, is the X6021 connection which is missing on the harness the guy sent me, aswell as the one I have now.

Do you know any websites in Germany or elsewhere in Europe, where I might be able to find this harness?

 

Sadly not. I bought my harness with the engine. Maybe you'll have luck going to a junkyard or similar to find the parts you need yourself, or find someone who's parting out their M54 car

 

After a few hours searching, I found a guy selling it in Germany. Instant purchase.

That should arrive around thursday, so hopefully it'll be running before next weekend.

Will post an update when something happens

 

Did you ever find out if your oil level sensor worked like it should?

 

hi, swapped an m54 b30 into my 318 but now im stuck with the harness, ive got the engine harness to match ms43 but the body harness has the connector for the bosch dme
is that similar to what youve done?

 

Yes thats exactly what we've done

As written above, you just need to rewire pin nr 2 from X6011 (green & brown wire in my case) to the empty spot on X6021.

Also make sure you have coded EWS to the new ECU if it itsn't coded out from the new ECU.

Im still waiting on the correct harness to arrive, but I'll be doing this exact thing in a few days.

Post an update if you get the engine started

 

Not sure if this is the same as yours? Going from Bosch to ms43 so connecting body harness to ms43 connector, got it mostly done, just connecting it

 

I swapped from ME9 to MS43 (n42 to m54) and made sure i got transmission harness, engine harness and iginition harness for the m54 engine

Plugged everything in as normal and all I have to do, as I understand from "Cvariable", is to remove pin 2 from X6011 to pin 1 on X6021

I didn't touch any of the wires for the DME as you're doing

 

Ah so you swapped the body harness also?
I don’t have my obd port working yet, also had to wire ignition switch to 12v port in the car.
Might have to buy a body harness hm

 

hi,
sorry to jump onto the post late but,

@FrederikBV

did you have the loom for the m54 engine, gearbox and ecu? was it literally just exchange 2 pins and all else was/will be fine? no major cutting and splicing into the existing loom on the 318? just asking as got a 320i m54b22 (rear end crash) and a 318i n42b20 (head gasket gone) and looking to make a start over the weekend, will have the engines and boxes swapped out in a day just the wiring side of things that i'm uncertain with.

cheers

 

Hey guys, sorry to not answer the last question. This thread has been invaluable in my swap too.

Done a m54b25 (2002 Facelift 325i) swap into a 318ci Vert (factory n42 manual). I've completed the above steps in the wiring successfully but I have one question. Has anyone transferred over an E box fan into the new car?

My 318ci didn't come with an ecu box fan and I'm wondering if I need it. And if I do, how to wire it up.

Cheers Legends.

 

 

Hello

I am also working on from 318 to 325 I am now also against the wiring car rotates around only start no doubt ignition

but the cable does not go over the black wire and the green wire do I have to disconnect them and connect them in the right place?

 

 

hi, i indulged in inserting the m52b28tu engine into the bodywork where the n42b20 engine was. All my wires match except the k62021 and k6011 connectors can anyone tell me how to connect or reconnect them? It would mean a lot to me and thank you very much in advance

 

Can somebody help me?, I have the same swap going on but with N46 and my DME/ECU is Bosch MEV9 and the connector for ecu is wayyy different than this N42 one. Im not an electrician so my head is fucking exploding since i can't figure out what to do, any help is appreciated.
And can someone tell me how to read the "X60001" etc. ty

 

i have done the same as you and have got the car running although i cannot connect to obd and alternator light doesnt work and few other things.