N52 Swap Discussion

[wazzu70]

In the ECU does the P code = hex code?

P3300 = 0x3300 etc.

[nando]

I had it connected to pin 18 on the old version of my wiring spreadsheet that’s linked way back.

It’s also connected here:

https://oomsgfx.com/misc/S54%20Swap/DIY%20Posts%20on%20Forum/S54%20SWAP%20WIRING.pdf

I expect at minimum that this allows a DTC to be stored in the DME for a failure to start. P0512 is “Starter Request Circuit,” so it’s possible this connection is only ever used to log a failure to crank to diagnose a bad starter connection before you buy a new starter motor and pull the intake manifold off.

Btw, please try to post errors with BMW hex code values - not generic SAE P-codes. ;)

Two problems with SAE vs BMW:

1) BMW has many error codes that go way beyond the scope of P-codes definitions. At best, you'll get a generic description.
2) In the DME calibration, everything is defined with the BMW hex error code - the same thing you'll see in INPA. Basically, when figuring out a DME function and associated errors, P-codes are completely useless. On the other hand, I can trace BMW hex codes to specific locations and states of memory

You can probably find a translation for SAE to BMW, but my brain isn't that big, lol. It's best to stick to the BMW definition, since many of their codes don't have an SAE equivalent anyway.

[nando]

I'll have a look at my bench flash harness - but there are 3 power wires that I remember. One constant, one start - and a wake-up signal that is effectively just an ignition switch signal, since we don't need the CAS or EWS modules.

On the E90, wakeup does stuff like prime the fuel pump when you open the door. Not something we need on the E30, but you still need it for things to run properly.

[nando]

I had it connected to pin 18 on the old version of my wiring spreadsheet that’s linked way back.

It’s also connected here:

https://oomsgfx.com/misc/S54%20Swap/...P%20WIRING.pdf

I expect at minimum that this allows a DTC to be stored in the DME for a failure to start. P0512 is “Starter Request Circuit,” so it’s possible this connection is only ever used to log a failure to crank to diagnose a bad starter connection before you buy a new starter motor and pull the intake manifold off.

There's a constant battery supply, I don't remember the pin off the top of my head, but the wire label is consistent across every BMW, even as far back as the E30. It's one of the main power pins on the large connector.

But actually, both MSV70 and MSV80 have non-volatile memory - disconnecting the battery does not erase error memory, fault memory, stored codes or anything else. That only really worked on OBD1 cars.

[nando]

Here's my wiring question: Pin 2 of the X6001 is the "Start signal" that comes from the car access module.

The S54 swaps have a similar pin and the explanation is as follows "6. Starting signal [ wire this to pin 18 on X20 it signals dme that engine is cranking]"

This makes absolutely no sense to me as the motor know it's starting from crank sensor signaling rotation.

Is this only related to "convenience start" or is it actually required?

Wire it to the ignition switch. The engine will not start without this signal.

Actually, if you think about it, the E30 even functions in a similar way. The ignition is not directly activated by the key - the key triggers a circuit in Motronic, which in turn activates the main relay and then physically powers the DME, coil, etc.

[hubcapboy]

I had it connected to pin 18 on the old version of my wiring spreadsheet that’s linked way back.

It’s also connected here:

https://oomsgfx.com/misc/S54%20Swap/DIY%20Posts%20on%20Forum/S54%20SWAP%20WIRING.pdf

I expect at minimum that this allows a DTC to be stored in the DME for a failure to start. P0512 is “Starter Request Circuit,” so it’s possible this connection is only ever used to log a failure to crank to diagnose a bad starter connection before you buy a new starter motor and pull the intake manifold off.

[hoveringuy]

Here's my wiring question: Pin 2 of the X6001 is the "Start signal" that comes from the car access module.

The S54 swaps have a similar pin and the explanation is as follows "6. Starting signal [ wire this to pin 18 on X20 it signals dme that engine is cranking]"

This makes absolutely no sense to me as the motor know it's starting from crank sensor signaling rotation.

Is this only related to "convenience start" or is it actually required?

[nando]

nando : The C101 gives us vehicle speed to the Motronic on pin 14. Motronic uses that to change at least idle speed when the vehicle is stopped. The MSV70 accepts a signal (on pin 17 of the X60001) from the dynamic stability control which is called "signal processed wheel speed, rear right." It seems curious that this wouldn't be done over CAN on the modern computer, but if it IS given its own wire, I expect that means the DME will understand the e30's signal?

My example MS43 wiring I've been referring to doesn't use that signal, but you reference it here:

https://www.r3vlimited.com/board/for...p-speed-signal

Just checking that the same holds true for the MSV70... it sounds like the DSC is just "faking" the vss pulses.

Yeah, surprisingly it comes from a wheel speed sensor, not CAN. It's actually very simple - I just change the number of pulses per mile (the "K" factor) from whatever the E90 is to 9 for the E30 diff sensor, then adjust for tire diameter. Fortunately it's an unsigned DWORD so there's plenty of room to adjust it.

You of course need to run the signal from the cluster (that gets processed through a little chip on the speedometer PCB), which goes to the C101 anyway - and not directly from the diff sensor, which is just a reed switch and presumably quite noisy. If somebody wanted to ditch the E30 cluster, you can salvage that chip and make your own signal processor for it, the function of it is pretty dang simple. This is what I was doing with my E46 M3 cluster that I finished but haven't got around to making it all plug in.

MS43 does use VSS as does basically every DME since at least MS41 - it's used for things like VANOS actuation and a ton of other things on MSV70. But, most people with those older DMEs left it disconnected (rather than just dealing with it properly), and worked around the issues of it being missing by changing the VANOS maps, etc. so it wouldn't run in limp mode.

[hubcapboy]

Ok. Here's an attempt. This should incorporate:

-EKP under the hood and driving the fuel pump through the C101
-All connections to the C101. No check engine light is provided, but I'm extending that to the glove box for later use. Service reset will be a momentary switch at the firewall, oil pressure is taken from the harness, oil levels are taken from the e30 switch via an abandoned secondary O2 sensor circuit.
-Econometer signal from Steve's former Seattle Circuit early model taking a signal from an injector
-OBD2 plug using ISO 9141-2 K-line.
-Accelerator pedal that I forgot to draw traces for but trust me they all go to X60001
-A spare PT-Can plug in the glove compartment for later use.
-An American Autowire 11V threshold charge light trigger
-An added circuit for the 2nd coolant temp signal for a double temp sender (one for gauge, one for DME)

Fortunately I've never been asked to design a PCB. This is messy laid out flat... it's not as bad as it looks.

n52_E30 HARNESS.pdf

[hubcapboy]

nando : The C101 gives us vehicle speed to the Motronic on pin 14. Motronic uses that to change at least idle speed when the vehicle is stopped. The MSV70 accepts a signal (on pin 17 of the X60001) from the dynamic stability control which is called "signal processed wheel speed, rear right." It seems curious that this wouldn't be done over CAN on the modern computer, but if it IS given its own wire, I expect that means the DME will understand the e30's signal?

My example MS43 wiring I've been referring to doesn't use that signal, but you reference it here:

https://www.r3vlimited.com/board/forum/e30-technical-forums/24v-engine-swaps/m54-s54/382375-mss54-s54-swap-speed-signal

Just checking that the same holds true for the MSV70... it sounds like the DSC is just "faking" the vss pulses.

[hoveringuy]

458lbs with everything except oil and exhaust.. Includes A/C, engine mounts, wiring, the shifter, G6-17 transmission.

M20+G260 is about 497lbs.

[hubcapboy]

My blue connector Pin 7 is labelled "Blue Relay 87." That shows up here:

https://www.newtis.info/tisv2/a/en/e90-330i-lim/uI4HGeS

If anyone can decipher the A4010 and give me confidence this is just ignition switched power that would be great. I've clicked through all the fuses listed on the junction box, but I don't see them. I'm sure this is "oh duh that's terminal 30 or terminal 15 or something something" but my eyes hurt...

[hubcapboy]

Here's my thingy diagram of the three harnesses above that are mysterious. It looks like I forgot to connect pin 6 of the green connector, so the power supply for the coolant pump will need to be a mystery for now (edit: I found it... fuse 09 should go to pin 6 instead of pin 5. Pin 5 just goes to the ground bus). There's a pdf attached to the post which reads a lot better that the jpeg... but honestly this all hurts my eyes compared to looking at it in autocad with a black background.

My next task here is to compare this to the X3 harness I have to see if there's helpful length and to the Z4 DME pinout to make sure it works with the flash.

Then I can half-tone everything that stays, highlight everything I don't need, and overlay the connections that I need to make to the C101 and e30 dash for the accelerator and OBD.

[hubcapboy]

I don't know how helpful this is going to be for everyone else, but based on what I've just learned this has prevented about 12 boneheaded "I wonder why it doesn't start" moments and maybe 3 "I wonder why my battery keeps dying" moments.

I know all the circuit information is in the TIS, but for the e90 there's 3 or 4 revisions of a few parts of this harness, and the TIS only lets you look at one little part at a time. I end up chasing one circuit through and forgetting where I was. This is an attempt to document the 2006 330i harness that I have to start with... so that I can compare it to the X3 harness that I think I bought for some additional length, and so that I can understand how to sew in my additional wiring, or re-use wires that I won't be using. The wiring harness can be broken down into four parts by unplugging connectors.

X60001:

This starts out pretty anticlimactic. The X60001 connector goes into the smaller of the two DME plugs. The reason this is cut off from everything is this handily only contains wires that go back into the dash. None of the X60001 conductors are part of the engine harness... this is the DME's connection to the interion including CAS, Battery sensor, Brake light switch, exhaust flap, accelerator pedal, clutch switch, wheel speed, OBD... we're going to be using a lot of these later for connecting to the car.


The Crab Harness:

My brother named this the crab harness. We used to have a crab intake, we may as well have a crab something. this is mostly sensors but also has the DISA changeover plugs, throttle valve and the starter trigger. It includes the X60002 connector from the small DME plug (which is mostly 02 sensor related) and the X60005 connector from the large DME plug (which is the largest connector and has most of the engine business sensors as well as the BSD bus for the alternator and oil condition sensor). This harness also includes a relay for the crankcase breather heaters, and everything that doesn't go back to the DME goes to a Maroon X60551 connector.


The Rail Harness:

This harness has two plastic rails, one with the 6 injector plugs and one with the 6 ignition coil plugs. Each rail has some "front of engine" sensors plopping out of it. The valvetronic motor pops out of the middle of the ignition rail. All of the ignition signals connect to the X60006 connector in the big DME plug, all of the valvetronic wiring is on X60004 in the big DME plug, and all of the fronty engine stuff like VANOS solenoids, thermostat, water pump, the eccentric shaft sensor for valvetronic, the camshaft position sensors, and the oil pressure switch return to the X60007 connector in the big DME plug. There's also a valvtronic activation relay hanging off this harness, which is powered by the positive lead ring connector. I don't understand why this is powered separately, but I expect I need to dig up a fuse for that.

Everything that needs to be passed on to the car such as the AC compressor signal, or several different power supplies is passed to a green X60552 plug.



The power harness:

The power harness looks small, but honestly this is a huge mess. This was the hardest part to figure out, because powers and grounds are spliced, there's fuse blocks... ugh. The power harness plugs into the crab harness with the maroon X60551 connector, and the rail harness with the green X60552 connector. It also powers the DME with the X60003 connector, which is in the small plug. It has a B+ distribution which is the main power for the engine, and needs a 60 amp fuse added. All the grounds combine here and go to chassis, and there are 7 fuses. This harness also has a blue plug that goes to the chassis with the AC compressor signal, the reverse switch (which is the long protected wire that we won't need because our reverse switch is chassis-side already), the starter signal... the wakeup signal... the CAS injector relay signal... it's basically the e90 equivalent of the C101.

[hoveringuy]

Awesome! I want.


"The weapon holder in the central rear seat armrest provides space for an MP5 and three magazines. The holder is fitted with a lock, which is operated via a switch operated from the front seats."