I've been working up a 'no com' on my son's 2005 Mini Cooper, and have hit a wall. He has had an intermittent OBD CEL with no drivability issues. When I hook up my three scan tools (Autel Maxisys 906BT and two others), I get proprietary body codes but no OBD codes, no engine data, no fuel trim, cannot communicate with engine computer, ABS, or EHPAS. However I am able to interrogate multiple devices on the K-bus system, I can communicate with BC-1, and the DS2 pathway is intact. So, I installed a breakout box on the datalink connector, and using my Picoscope I find that the D bus is shorted to ground. This was proven by using a 170mA test light inline with a power probe, showing that with a one second test the light glows brightly but the scope shows only noise centered around zero volts. The DS2 line is intact, showing 12 volts and the test light fails to light on that line using the same test. This 2005 version of the Mini does not have the 14/6 links to the Can network through the OBD connector, but in view of how well the car is working I expect the CAN network is fine.

At that point I began removing devices, one at a time, on the Diagnostic Bus, thinking that I have a shorted module. I started with the Power steering, no change, then I moved to the EMS2000 computer, no change, then I removed the ABS connector, no change, the short to ground persists. His car is a manual transmission, not CVT, so I don't think he has a transmission module, and even though the dealers repair manual shows a Diagnostic bus link to the IKE, I don't see the link in the wiring diagrams in the dealers repair manual. The dealers diagram also describes a LWS module for steering angle, but on reading the manual I think that one is for the Cooper S only. His car has no traction control or DSC.

By this point I'm thinking I'll have to go old school and painstakingly trace those wires. The repair manual shows a central splice point of the Diagnostic bus line, but unfortunately they have not labelled that and I have no idea where it is, presumably behind the dash somewhere. I have removed the paneling at the drivers footwell and found no corrosion, and I have blown out the water drain for the sun roof. I have inspected the datalink OBD connector, no corrosion or wiring issue there.

Any ideas? Anybody know where that main splice is for the Diagnostic bus?

 

Please explain what you have and have not? Does the car run okay? Does the Kombi (speedometer and also tachometer) work okay? Are there driveability problems? If no problems there, then your CanBus seems okay. What is EMS2000?

On the D-Bus is the GIU (transmission interface), ABS (brakes), EHPS (power steering), and also the MCU (motor control unit) and the Kombi (speedometer plus tachometer). These problems can be horrifically difficult to troubleshoot when intermittent so a permanent "short to ground" is a wonderful gift. With every component unplugged, if you still have a short, then clearly it is your harness. But check to unplug those Kombi and MCU connectors.

I bought a complete (used) main harness but it may not have the D-Bus included as I don't recall seeing an OBDII connector. Maybe there is a plug above the OBDII connector.

Part of the main harness from the battery and MCU into the back of the dash goes past sharp metal flanges near the steering wheel support with no buffer. A sheet metal edge guard can help those areas. I hate climbing under the dash and twisting my back.

Good luck,
Peter

 

Thanks for the reply, Peter! After hours of chasing an occult short to ground, I found it! There is a cylindrical connector just behind the left headlight, not shown on the dealers repair manual. I was able to divide the problem in two by proving the short was distal to that connector, which allowed me to chase the distal end all the way to the power steering module. That wire takes a sharp turn under the return line for the heater core, and the wire was pinched against the motor under that coolant line. Insulation had melted against the engine, and in fact the wire was broken, though it might have torn when I removed it. I didn't find it until I completely removed the length diving under that corner on its way deep to the exhaust manifold. A short length of repair wire, solder, dielectric grease and heat shrink, careful reassembly, and Bob's your uncle. I recorded the experience for a video on Youtube, I'll probably post it in the next week to help anybody who has a similar problem. I guess that wire got trapped by a previous mechanic, since there were scattered signs that this engine had been worked on.

Regarding your questions, BMW have all kinds of confusing synonyms, like General Module=BC1=Body Control Module=Main Controller=ZKE; and engine computer=EMS2000=DME2. It seems to get easier once one learns the strange lexicon. The car was behaving completely normally, the history code after I got the Diagnostic pathway working was P-0456, a minor Issue I'll deal with later. It hasn't recurred since the repair, just a history code right now. The Instrument cluster worked fine, GIU was absent since it's a manual transmission. I never did find that central splice, I don't even know for sure which side of that cylindrical connector it is on.

 

All right. Good job.

 

For anybody who is interested, I posted a detailed video of how this repair was done, here on Youtube. There is a real paucity of information on the net for no comm problems, this may help others who encounter similar issues in a Mini. It's not technically difficult, just application of basic principles, though the needle in a haystack challenge is hard to underestimate.

 

Nice video. I've been down that road many times. Ha! Pulled many of the same components. My 2005 is not worth that much so it has become a mental challenge. I can solve this!!!

I've also found the frayed power wire under the battery. I wrapped mine in a split rubber hose to protect it. I've also found wiring problems that seemed like the problem but didn't fix it. Applied TESA to the frayed harness, cleaned a dozen ground points, cleaned and put dielectric grease on ten connectors, replaced frayed wires, I even replaced all of my wheel speed sensors.

My current problem is intermittent CanBus communication loss. I think the solution was to remove the Tachometer (go figure) recommended by another forum post. My only guess is that the Tachometer talks like a five year old at Thanksgiving dinner. Nothing can communicate while it babbles on relentlessly. I don't know how to troubleshoot that; however, my plan was to disconnect things looking for a similar set of error codes so maybe I would have found it by myself. Anyway, it has been running great without a Tach.

Peter

 

Hello,
Nice video!! I had a similar problem but in my case i get link with ecu, abs and Hydaulic steering pump. And no link with ike.

 

Amazing video. It has helped me try and figure out why my 06 PW/B can't connect to the diagnostic bus (dbus / kline).

For future reference, the round cylindrical connector with 10 pins is X6011.

I had water leak from the sunroof drain and had cleaned up corrosion on the 54-pin connector under the fusebox.

When I disconnected the X6011 plug for the first time, I had brown water come out of it. Hm.

The only logical reason for this is that the cover for the headlamp washer flew off and water flew in through the hole because that plug is right there behind the opening.

Also I no longer showed a short to ground on pin 7 of the breakout box after disconnecting x6011.

When I put the toner on pin 9 (violet / white stripe) for the DBUS/KLINE connection on the distal side of the connector, the signal dropped significantly right there at the connector itself.

After tearing the aibox out, ecu, and the motor mount and inspecting like a madman, my next step is to snip the violet/white stripe wire on both sides and just jump it and see if my obdii scanner will connect to the dme.

Pray for me.