Hi all,
My 2012 MCS hatchback R56 (N18 engine and automatic transmission) needs a replacement engine wiring harness due to some damaged wiring. My question is for anyone that is familiar with replacing one of the wiring harness is if a wiring harness from a 2013 MCS S with manual transmission (PN 8605260) can be used to replace my damaged harness (PN 7621311)?

RealOEM shows the required harness for my car as PN 12517621311 and is superseded by PN 12518605260 (02/01/2013 — ), Exchangeable retrospectively

 

engine wiring harness of an automatic or manual transmission is the same. HOWEVER, you need to pay attention to the high pressure fuel pump. That's what makes the two different. make sure the donor Mini has the same HPFP type/part.

 

minitobe,
Thanks for the info. I couldn’t think of any reason there would be a difference in the engine harness between auto and manual but still not sure whether I can use the superseded wiring harness. Both do have the connector for the newer HPFP. My MCS has a manufacture date of 03/12.

 

The issue is not auto or manual. The issue is if you have continental high pressure fuel pumps the wiring from an engine Bosch high pressure fuel pump WILL be different. Sure the plug to the pumps is the same BUT the pin assignment is different on the ECU.

what's the hpfp you have? What is the hpfp on the donor car?

 

MiniToBe,I appreciate any help you can provide. Looks like you have quote of experience with tinkering with these cars.

My 03/2012 MCS has the Bosch HPFP. The donor harness came from eBay and I’m told by the seller it came from a 2013 MCS with manual transmission but didn’t know the VIN or manufacture date.

I checked the connectors for both the HPFP and the fuel rail pressure sensor (FRPS) on my harness and compared them to the donor harness. The wiring for both connectors was exactly the same but oddly enough the pins were not like the assignments listed in the Bentley Manual and seemed somewhat swapped between the HPFP and the FRPS.

Here’s what I recorded:

HPFP
Pin 1 (WS) went to Pin 30 not 36
Pin 2 (SW) went to Pin 32 not 34

FRPS
Pin 1 (BL) went to Pin 36 not 30
Pin 2 (WS) went to Pin 38 not 28
Pin 3 (GE) went to Pin 34 not 32

I’m at a loss right now and not sure what to make of the donor harness. I’ve not come across any issues with Bentley schematics being wrong.

 

The Bentley manual might be showing a harness from a harness with a Continental hpfp. At this point, compare the colors. The Bosch hpfp connector has white and black wires. Not sure about the rail sensor but if you match colors, you should be fine.
if it is still risky, find another set from a know bonor VIN.

 

the Bentley manual shows both continental and Bosch HPFP pin connections for the N18 with the color codes I listed above. The colors match up between the two wiring harnesses. Both wiring harnesses match for the HPFP and FRPS. I bought this car a few months ago with 51,000 miles and it had a CEL with codes for misfires on 3 cylinders and random misfires. I inspected and replaced the spark plugs, ignition coils, and fuel injectors. I cleared the code but the car wouldn't start. After some troubleshooting I saw that the fuel pressure was way high at around 3600 psi. I disconnected the FRPS and the car started but was limited in power and I got the code P0193 for FRPS circuit high bank 1.

I replaced the FRPS and got the same code. I then checked the wiring for the FRPS and the connector showed 5v on Pin 1, 0v on Pin 2 both as expected, but 5v on Pin 3. I thought this should only have voltage on the line relative to the sensed pressure but with it disconnected it should have been 0v. I thought maybe this line might be shorted to another 5v line but couldn’t find any damage.

Earlier today, I replaced the FRPS and reinstalled my original harness after checking continuity on all pins. Once again, car starts and idles fine but has the same code of P0193 and is limited in power. Just for comparison, I partially installed the spare harness (PN 12518605260) and I get the same readings on the FRPS wiring harness connector.

I’ve been working on this car for several months trying to figure this out but back to square one. I’ve replaced the fuel filter, checked the LPFP pressure, replaced the HPFP, replaced the FRPS, had the BMW “specialists” diagnose a “bad” ECU (I think they caused it), cloned and replaced the ECU, checked the wiring harness, and replaced the FRPS again.

Does anyone out there know my FRPS connector has 5v on the sensed line? Anyone seen wiring discrepancies with the Bentley Manual schematics or those on the newtis.info website? I live in Guam and we have limited service shops and replacement parts takes 2-3 weeks to get. I’d love to get his car I running right but so far it’s been running me ragged.