Busy Weekend

Everybody’s favorite is wiring, right? I had a very busy weekend creating the pass-through wiring harness shown here:

M3 Passthrough Harness 1

M3 Passthrough Harness 2

The SMG gearbox talks to the DME on a CAN bus in connector 2. Since this is the smallest connector, it was fairly simple to wire up the pins to pass through, and then tap into the two wires I needed to bring over to the M1. As you can kind of see in the first picture, the pins on there are designed to go into a printed circuit board, so they must be bent out of the existing shape so that you can solder wires to it.

This is fast, easy, and simple if you’re doing this all the time.

It’s been months since I soldered last. So it was none of that.

Here’s how the car currently looks. This is with the stock suspension back in, and the removal of the tint from the front windows. You can kind of notice the difference during the day, but it is extremely different at night.

M3 Exterior with Fixed Suspension

I don’t think the E-Box was ever opened: M3 E-Box 1

M3 E-Box 2

Interestingly, there’s no relay attached to the cover on the M3 like on the 330 with SSG. M3 E-Box 3

Stock wiring, all nice and tidy: M3 E-Box 4

With the adapter mostly in place: M3 E-Box 5

I already had a power connector pass-through, so that was used to power the M1.

One thing ProEFI got right in their design was the mounting hardware is cheap and functional. The first piece uses two of the three existing mounting places in the passenger bin to put a support bar… M3 Passenger Bin 1

…which a plate is mounted to which has the ECU, and on the back igniters (and on the original kit - reisistors to fool the DME). M3 Passenger Bin 2

M3 Passenger Bin 3

So after this, we’ve got our ECU in place, our data line run…and no way to control things or get the data out of the ECU. We need one more item. USB to CAN!


USB is fast, but in practice even USB 2 isn’t that fast (hence why we have 3.0 now). Motec went for a very elegant solution here - Ethernet.

Ethernet, using IPv6. For those that don’t know, IPv6 is the ‘future’ (it’s been the future for 15 years) IP addressing scheme. It solves the networking problem of running out of addresses. Instead of 32 bits of addresses, or 4,294,967,296 addresses, IPv6 is 128 bits, which can have

3.4028236692093846346337460743177e+38 addresses.

That’s a lot of addresses. It’s enough for approximately every square meter of the earth (or something just as absurd).

It also supports auto-discovery, and fixed addressing using a known pattern. It’s these last two features which is what I think attracted MoTeC to using Ethernet. It’s also much more standardized…and if you get creative, you can do this over WiFi. No WiFi for now. So lets put in an Ethernet cable.

M3 Ethernet 1

First we need to remove the screws for the glove compartment: M3 Glove Box 1

M3 Glove Box 2

Then comes the real fun. You have to fish a wire through a grommet that thankfully is already available for use. But this requires a bit of contorting. M3 Glove Box 3

When all is done, though, you have a nice cable jack available for you.

M3 Glove Box 4

The wiring in the engine compartment is pretty clean. M3 M1 and Ethernet Cable

After this was done, we used the Motec CAN Inspector software to dump what was being transmitted on the SMG2 CAN Bus. As I had been told by someone, the data is indeed unique on that bus. It’s not the same as the data we already have on the rest of the E46 series. That data is on another bus.