So the Idrive controller on my 2007 E91 3 series was playing up. Basically it would sometimes appear to hang but mainly the press to select/enter function would get stuck down. You could see from the display that it thought the button was pressed from the surround changing on the option select. The rotating part generally seemed to work ok apart from what seemed like it hanging.

So I bought an updated one (which didn't work because I need to code it and also needs a new console surround) but decided to have a go at fixing the original - figured a dodgy/noisy switch or something was most likely but knowing BMW expecting hall effect or optical sensors.

So as I pulled it out and swapped the updated one in temporarily I found that jiggling the wiring to the controller made the system sense button presses. Ok so could be a dodgy connection right at the connector rather than the controller electronics. Pulling it apart was not difficult and I found 2 optical sensors for rotation and 1 for button presses. I suspect the first 2 somehow also sense up/down/left/right since there is no other way. Neat either way.

Anyway here's what I found at the 4 pin connector that is the sole connection to the car.



You can see 2 pins of the connector underneath. There appears to be no solder whatsoever (either side) holding the pin header on. I did try pushing it out of the board but it seemed fairly well held in either by the 4 pins or the 2 black plastic mounting points (or both). I didn't force it though since I had no need to get it out.

So it seems they've either forgotten to solder it completely or are relying on some kind of press/interference fit. I've done quite a bit of volume electronics manufacturing and have never seen anything like this nor would I consider it, particularly for a high vibration, harsh environment like a car. So presumably BMW or their 3rd party CM have just stuffed up here. I'm surprised I didn't find much other than a Youtube video of some guy soldering 4 "cold solder joints" on the optical sensor (I touched them up too in case).

This doesn't explain why the rotation seems to work OK since the wiring is basically power, ground and 2 signal lines (CAN I think) i.e. everything goes over the same bus but perhaps noisy power was falsely triggering the optical sensor.

Soldering the four pins and after a quick test it seems to be functioning significantly if not perfectly now.

So thanks for reading the novel. Interested to hear anyone's thoughts. empegbbs was the forum I figured I get the best response (as always). There are too many BMW ones spread all over the place....

Oops.

Good find. Perhaps not many of these made it past QC and you were one of the unlucky ones. Do you find many other people complaining of the same problems online?

I've not found anyone complaining. I did just find another thread with picture which looks to be the same but they're complaining about dust/fluff clogging the optical sensors.

http://www.e90post.com/forums/showthread.php?t=1070338

Pretty clear that it is unsoldered too.

I'm surprised it lasted 7+ years.

I'm going to take a wild-ass guess and suggest that BMW are worried that stresses on the cable would crack any solder they might have put into those joints, so they instead tried to make do without the solder.

So yeah, solder seems a fine thing to do, but make sure you've got enough slack in the connector cable that vibrations and whatnot won't overstress the solder points.

That's something us empeg owners/fixers are only too familiar with.

Yeah no stress on this at all really. A 4 wire harness and plug similar to a 3.5" floppy power connector. Plenty of slack and just the weight of some of the wires itself.

Thread dig. So the SMG shift speed switch in my M3 had become a bit sticky. I think a tiny spot of soft drink or something had gotten in. I pulled the switch out and sure enough there was a very tiny little splash of something gooey on one side - a spot at best. Easy to clean up.

I looked a bit closer at the PCB and what do you know, another non soldered header. This switch isn't used very often and this one has never played up that I noticed.

First one in this thread was from the 2007 E91, this one was from a 2004 E46 so a different model run and quite close to the end of the model.

The switch is mounted to the centre console and has a fairly long cable the plugs into it so certainly no chance of stress on the cable. Even then I'd take a soldered connection over some kind of press fit.

BMW can't be serious that this is a good idea in an automotive environment can they?

So I'll be soldering this one too. The first fix I did has worked perfectly for 2.5 years.

Wait, am I to interpret from that photo, that what we're looking at is five individual loose separate pins which were press-fitted into those holes?

In your earlier example at least it was part of a connector assembly which had been press-fitted in.

Yes, the pins looked basically press fitted to the board with no sign of solder on either side. They were all individual and not held together in any way aside from the PCB itself.

I didn't try to remove a pin as it was otherwise working fine but I suspect they would have popped out fairly easily. Can't really tell from the photo but there was a bit of a kink in the pin. I had to put it back together and into the car, so it got soldered. So can't easily look again at this one.

I probably should just pull another module from the dash and expect to find similar bad manufacturing/design.

The first one did have the pins held together with the black plastic they used to make headers but also it had the plug into the board. But that was all.

Connectors on wiring harnesses are normally all friction-fit (crimped), so I guess they figured the smaller PCBs could also use similar tech?