BMW E30 M52/M50 Swap Wiring Guide | 24v M5X Engine Conversion Electrics Wiring Chart | 048
In this E30 build video I tackle the daunting task of wiring an M52 swap. Having recently installed the 24v engine conversion in my E30 I was keen to crack on and move the project forward in the direction of a first start.
Here's what I used in this video:
Solder sleeve connectors: ebay.us/z0qezW
Soldering Flux: ebay.us/fjBz1d
Wire stripper tool: ebay.us/aYNjWo
Heat gun: ebay.us/4YL6WV
A wiring adapter if you don't fancy DIYing: ebay.us/Ep1oGL
Or: ebay.us/oOKQHQ
Let's discuss whats involved in an E30 M50 swap wiring guide. For starters, you need to have the E30's original wiring alongside the wiring harness for your M52 or M50 engine.
In the most simple terms possible, you need to find a way to connect the M50/M52 engine harness to the E30's body harness, in place of the original engine harness the car came with. In my case an M40 engine loom.
Conveniently there is a large screw-locking connector on the E30's wiring loom, found just to the right-hand side of the wiring cowl cover within the engine bay on the bulkhead side. This large connector is called a C101 plug connector and effectively connects the E30 chassis harness to the engine harness via it's 20-pins.
The good news is that the chassis harness including the fuse box, can be left entirely intact for this engine conversion wiring. So you can focus on the engine loom side.
M52 engines can be found in a variety of BMW models, including the 3 series E36, the 5 series E39, and the 7 series E38. Each of them newer cars than the E30.
I believe the M52 engine I am swapping is from an E36, but whichever chassis its from, your M50 harness will have an X20 plug on it, which is the more modern equivalent of the C101. The X20 connector is a 25-pin locking connector of a very similar type to the C101 found on the E30.
What needs to happen, is you need to chop the X20 off your M52 loom and replace it with a C101 connector which can connect directly to the E30's body wiring.
Before we go any further, let it be known that you can quite easily purchase an adapter which connects between the X20 and the C101 to join your two harnesses together. However, there are drawbacks to this.
The main drawback in my opinion is the sheer cost involved for what is a relatively simple thing. I imagine the retailers of M52 or M50 wiring adapters understand how intimidating car electrics can be, and are charging accordingly for their loom adapters.
Additionally to this issue, using an adapter adds a lot of bulk to the wiring as you end up with two very large connectors instead of one which sits neatly in the carrier.
As my removed M40 engine and its harness has very little monetary value, I have no reservations on harvesting the C101 plug from it among other things to complete this e30 24v engine swap wiring.
Before I went ahead and started chopping wires, I took some time to compile a wiring guide table, or in other words a wiring chart for M52 swap. The table effectively takes the 20 pin wires from the C101 plug and their colours and maps them to the corresponding wires on the X20 plug.
This actually proved quite a difficult table to make as there appears to be a lot of variance in E30 wiring, I suspect they can be quite different depending on the model, year, market or even whether they had run out of a particular wire colour that day.
You will have realised that with the C101 only having 20 wires, to the X20's 25, we will have some redundant wires here. This should be no big deal providing we connect all of the key ones, bear in mind that the E36 is a newer generation BMW which has equipment that the E30 never had, such as climate control and cruise control.
After cross-referencing quite a few different pinout tables for the E30 and also for the E36 M52, I became fairly confident in what each wire does on both harnesses. There are still a few which I'm uncertain about, but thus far I can account for all of the important ones for getting the engine to run. See the wiring diagram in the video along with a more detailed explanation.
With that figured out, I went ahead and chopped the C101 plug off the engine side of the E30's wiring as far up as reasonably possible to give me a bit of extra wire to work with. I also chopped the X20 connector off the M52 harness as low as possible.
I followed my wiring table to connect all the wires together using solder sleeve connectors to make it easy.
With this done, I took my M52 harness into the engine bay and began connecting everything up, which was quite difficult but luckily BMW used a lot of unique connectors which help you identify which is which.
With this done I hooked the battery up and plugged an ECU in (one which I suspected still had EWS II on it). To my surprise the car now cranks on the key which is incredibly good news.
#e30 #e30build #wiring #m52 #m52swap #m50swap
8 окт 2023
