Z4-forum.com

I know this has been done before and isn't the most difficult of tasks, however thought it might be interesting to anyone who can get their hands on heated and electric seats.

My car had M Sports seats but they were manual and unheated. Dellboy sold me his Z4M seats that were electric and heated, I was looking at swapping them over and hoping the wiring loom was present to simply plug and play.

I had also bought a new centre switch panel from Pawnsacrifice with the heated seat buttons.

So on a very cold Saturday afternoon, I finally had the time to fit my new seats.

First job was to disconnect the battery, which is a nice easy job to ease myself in.

Next I replaced my old switch panel with the new one from Pawnsacrifice.



I had taken the panel on and off a few times, so when you get the knack, it is an easy process. Just unscrew some torx screws and the new panel fitted perfectly and was an exact match. Getting it back in is a fiddle, but after a few minutes of tweaking and twisting I got it back in. My plan was to install the One Touch Module whilst the panel was off, however due to the fact even by this stage I couldn’t feel my fingers I decided that would be for a warmer day.

Next job was to take the driver seat out of the car. This was a very simple process, just unscrew 4 bolts and detach the seat belt from the seat itself. Then just unplug the cable running from the seat under the floor into the car.



Having got this out (wish I’d put the windows down to help easing them out) I was able to hoover 6 years worth of mess from the cabin. It actually wasn’t that bad, I was surprised it was so clean.





As there are no occupancy sensors on the driver seat, it was a simply plug and play. I reconnected the cable and at this point also reconnected the battery to test the seat movement. Very little point putting seats into the car that I wouldn’t be able to move.



Happily, the seat immediately sprang into life moving when I pressed all the buttons. 10 minutes later, I had reattached the seat belt, hooked the seat over the bolts at the front, located the bolts at the back and tightened everything up.

I double checked all the movements, they were fine, and when I pressed the heated seats button, the lights came on. I think the seat had spent a long time without the heating element working, so it didn’t warm up very quickly, but I could definitely feel something, so I started work on the other side.

I disconnected the battery again and followed the same procedure to remove the passenger seat.



Once it was out of the car, I again hovered up and found 7 pence, which I can factor against the cost of this retro-fit! I then took my old seat inside the office to warm up a bit and to sort the minor issue of the occupancy sensor.

With both seats on their sides, I unplugged the sensor cable on the new seat and taped it to the frame away from the other wiring as I no longer needed this.



I unplugged the same cable from my old seat and traced it around to a black box. Out of this box came a blue wire and a white wire. I cut this and removed the box from the seat. I then connected my bypass unit (thanks to Dellboy for pointing me in the right direction) to these wires.









I then plugged this back into the connector under the new seat.



Then I had to venture out into the cold (it was about 0 degrees now) and test it in the car. I laid it in the cabin, reconnected the battery and turned the ignition on, hoping I wouldn’t see an airbag light. No light stayed on, and the seat moved on its base.



10 minutes later the seatbelt was reconnected and the seat was back bolted to the floor.



Everything worked perfectly. The only thing I forget to do was to reattach a plastic cover for the connectors under the passenger seat, so if I lose a connection I will take the seat back out and reattach it. I also scraped the skin off one knuckle and (ehem) broke a nail

A quick tidy up of all the tools, the hoover and 5 minutes of wrapping my hands around a hot cup of coffee.

The journey home was enjoyable and warm!

So a big thank you to Dellboy who sold me the seats, and also pointed my in the direction of the occupancy sensor along with a great step by step guide of how to fit it all together.

Thanks also to Pawnsacrifice who sold me the centre panel and offered real advice and encouragement on fitting everything.

I know this isn’t the most complex or taxing of projects, however it is by far the biggest undertaking I have ever carried out on a car, and I am really pleased I was able to do it without any issues.

I now am looking at a refurb for my 18” MV2s, two new number plates and apart from a really good clean, clay and wax, I can look to enjoy the car this summer!

I now have two M Sports seats sat in my office looking very lonely and ready to go to a loving new home. Of course whoever buys them will have to attach the black box from under their existing seats to ensure the sensor works. I am not sure of precisely what it does, but I know there are people on this board who are far more knowledgable than me to ensure you do whatever is necessary correctly.

I will put a post up re the seats as soon as I can and am open to good offers as I have a lot of money to try to get back from all the money I have spent!

Thanks

nice write up, hope the fingers have warmed up!

a11y is looking for a set of M seats...

Nice work - good to see it all in and working (phew)

Good work on the write up too - can never have too much info, especially pictures.

Now you've had the ash tray unit out fitting the one touch will be a doddle.

Excellent write up. I bet you get a long list of bods wanting your old seats...... ill be in the queue too.

Excellent write up. I bet you get a long list of bods wanting your old seats...... ill be in the queue too.

Good job and write up.

I was half expecting to read oyu connected the battery, dropped the window to clean up and now had an airbag light on, but no such mistake

Well done, always very satisfying.

Interesting, uh, work shop

So the heaters and electric seat wiring is already present... They vey kind on BMW part!

Your office looks like mine.... Hope you didn't do this near my desk while I was away

But a good job and write up, always satisfying getting a job done yourself.

Great write up, and a brave man doing that outdoors in that temp! I retro-fitted heated non-sport seats into my Z4 and did it in similar temps, not fun.

BTW I've emailed you about seats...

Nice write-up. Puts me in mind of when I did the same to my old Z

All working perfectly,........ unless, as a passenger, your airbag won't deploy if the worst happens.

gookah wrote:All working perfectly,........ unless, as a passenger, your airbag won't deploy if the worst happens.

To be fair, you've got it the wrong way round mate, but yeah, that would be very poor form. It will always fire the airbags - the risk is having an accident with only the driver in the car and the airbags doplying for a passenger that isn't there - damaging the dash and the passenger door.

A silly question
could you use the electric base off standard seats and retro fit to non electric m-sport seats like yours? i wonder if bmw just change the top part and kept the base as a cost saving exercise.

Does the fact that the black box under the seat is unconnected make the car think that someone is in the seat? If so, that would explain why my seatbelt light flashes up and the warning chime going mad if I don't have seatbelt clipped in. It's making me mad having the seatbelt clipped in all the time and a pain when a passenger gets in.

how much you looking for for the seats?