I have a 02 mini s with a bad BCU. I have found a donor car and am working through replacing all the necessary modules. I am down to removing the bad BCU, bt cannot get the Green plug unplugged at the bottome of the BCU. Does anyone have any clue how that plug is released?

 

Slide lock, you need to find which way the lock needs to slide and just grab it and give it a good slide. It should come apart, unless it has corrosion in it, which we have seen multiple times..

 

Hi, did the BCU swap out work for you?

I have all the symptoms of having a bad BCU. I have read that exchanging the BCU still has to be programmed by the dealer. Have you had to do this?

Any help would greatly appreciate it.

 

Bad BCU???

This has been intensely frustrating. Occasionally, and maybe related to a rain event, imy R50 does the following. The tachometer stops working, dash lights all light up, the CVT starts shifting very erratically, (like to first gear on the highway). Sometimes clearing the OBDII codes fixes it completely for two weeks.

It seems like the "rain in the BCU problem" but I don't see any sign of water. I've had the MCU out and checked, soaked the wiring harness in the cowl area to no affect. The BCU looks fine but there are many splices in the harness to the four connectors (look like old dealer repairs).

As bizarre as it seems for a $1000 car, I'm planning on replacing the entire wiring harness, the BCU, the MCU, and the battery box and lid.

And I don't know if this will even resolve the problem.

Peter

 

You need to pull out the BCM and look at it, you might have corrosion built up from previous water. Open it up and check the board, it might be corroded.

https://www.northamericanmotoring.co...working-2.html

 

I opened up the BCU and it looks perfectly fine. No sign of corrosion anywhere. However, there is a smudge on the plastic cover that kind of looks like mildew so maybe there is high humidity.

The right side floorboards and carpet also look perfectly fine with no sign of water infiltration. The rear near the tailgate also looks dry. I put paper towels under carpet and behind door cards to telltale of any hint of water.

Since it was "sensitive" to rain, I assume water is getting somewhere but I can't find it.

Peter

 

Check the a-pilliar for those drains (sunroof) and behind the carpet.

 

I pulled the headliner down slightly and everything looks good. I then poured a cup of water into the moonroof troughs and the water poured right through the drains and onto the floor.

I also got another harness and carefully grafted replacement wires into the 13 wires that had been spliced to the BCU.
That is,

1. Carefully removed the pin from the plug on the donor harness plug,
2. cut that wire 14" back,
3. removed the spliced wire pin in the car,
4. cut it back past the nasty splices,
5. soldered them together at a good harness location,
6. put two layers of heat shrink on the joint, and
7. when all 13 were complete, I wrapped the harness in TESA.

I then cleared the codes and it drove fine (but for how long?) However, when I drove it again I got an SES light PO1611 Transmission communication fault I think. I cleared that fault and it still drove okay and without another fault (but again, for how long)?

Peter

 

Not long. I swapped in another BCU and it ran fine for a few miles. But then it went into fault mode and revved to 3,000 rpm all the way home.

Does the BCU need to be programmed to the car? I would have thought it wouldn't run at all if that were the case.

Peter