Obd1 318 to obd2 328

[Jonaheh]

Hey! First post but damn have i ever spent a lot of time on this forum. Ok so I have a 94 318 manual that’s super clean and a 97 328 auto that isn’t.
I would like advise for what’s needed to be swapped over for this to happen. The plan is to use the 318 trans , driveshaft and diff and swap everything else.
Now I have the 318 motor already out because it was blown.
I see a lot of people saying to use m50 obd1 engine harness but I have everything from the obd2 car. Do I need to completely gut both cars and swap the body harness too?
I am a mechanic but never done a “engine swap” I’ve replaced a bunch but never swapped a motor from one chassis to another.

Any info would be awesome thanks guys

[E36M3LX]

you can re-pin bmw engine wiring harness plugs. just need to find pin-outs for the car and for the m52. I have a pin-out for the m52 but you'll have to find the obd1 318 pin-out yourself.

m52 pin out.jpg

[Jonaheh]

you can re-pin bmw engine wiring harness plugs. just need to find pin-outs for the car and for the m52. I have a pin-out for the m52 but you'll have to find the obd1 318 pin-out yourself.

m52 pin out.jpg

So what you’re saying is I can use the obd1 body harness (fuse box back) and use the obd2 engine harness and plug it in by changing the pin out on the plug? On the m52 there is no 3 block of relays that is built into engine harness though ? Would I not need the body harness for the throttle or is it drive by cable ? I’m sure this would all make more sense if I had pulled the 328 so far but it’s just so damn cold out.

[E36M3LX]

So what you’re saying is I can use the obd1 body harness (fuse box back) and use the obd2 engine harness and plug it in by changing the pin out on the plug? On the m52 there is no 3 block of relays that is built into engine harness though ? Would I not need the body harness for the throttle or is it drive by cable ? I’m sure this would all make more sense if I had pulled the 328 so far but it’s just so damn cold out.

m52 wiring harness has the 3 relays. engine wiring harness is very simple on these cars so it will be pretty easy. but yes i would just re-pin the connector for the m52 engine wiring harness to match the x20 connector on the body side of the car. throttle cable is is just a cable so simply use the m52 throttle cable.

[AJLM34A]

Here is a link for a lot of the older BMW factory ETMs;
http://wedophones.com/Manuals/BMW/

I installed an ODB2 S52 in a 94 325i and deleted a lot of the wires for ODB2 engine harness side and X20 body side components.
The only addition circuit/wire I had to add is a 12volt higher amperage in the X20 on the body side to power 4 O2 sensors.

Use control F on whichever wiring diagram is for your body and type in X20.

I would "guess" that the X20 wiring for a US and Canadian car is going to be the same, but it is not many wires and the colors and where they go to should be really easy to verify.