Mechanical Seats to Electric Seat Upgrade

[ANUSTART]

Does anyone know if the base Z4 is prewired for the electric seats? I have the cheap vinyl seats with mechanical adjustments and would like to find some leather electric seats. I could probably do some surgery and take a seat out, but wanted to check here first.

Thanks! Chris

[santov]

Yep, it's the same wiring the the alarm system plugs into.







Sorry, couldn't resist since you didn't sell me your alarm kit.

[ANUSTART]

I was asking for that one.

[The HACK]

I removed my driver's seat to see if anything can be adjusted to lower the seat another 1/2" and noticed that there were more plugs that plugs into nowhere than there were plugs that actually plugs into physical harnesses.

So my guess is yes all the harnesses are present and it should be plug and play. Can't imagine why there'd be one giant harness with a ton of wires when the ONLY electrical part of the seat is the occupancy sensor.

[ANUSTART]

Originally Posted by The HACK

I removed my driver's seat to see if anything can be adjusted to lower the seat another 1/2" and noticed that there were more plugs that plugs into nowhere than there were plugs that actually plugs into physical harnesses.

So my guess is yes all the harnesses are present and it should be plug and play. Can't imagine why there'd be one giant harness with a ton of wires when the ONLY electrical part of the seat is the occupancy sensor.

Ah, very good to know. I may have to pull a seat and take a volt meter to test and some photos for reference. Thanks!

[CFoote]

The 2003s and maybe some early '04s were shipped with a complete wiring harness no matter what options you chose; in later years they shipped cars with a wiring harness that was suited to the car.

I retrofitted power seats to my '05 and I originally had manual, heated, leather seats. The 12V +/- wires were missing and the single K-Bus wire to the General Module was missing to have the power seat memory function work.

It is not a big deal. Once you get your manual seats out, run a 12V +/- wire to the battery (make sure you put a fuse in line for each seat). You could run the wiring to the power distribution panel in the front of the car, but I didn't want to tamper/mess with the existing wiring (something could break, wires could get loose from their connections, it could be a mess and the Z4 is a tiny car, not a lot of room to work).

Once you do that (make sure you use at least 12 gauge wiring, if not 10, and thats for each seat), you can run a small wire up to the button panel in the center console. You can grab the K-Bus signal from there to get the memory seats to work. (check online for a Z4 wiring diagram and you can see which wire to tap).

That's about it. I would suggest getting Z4 seats as I believe the mounting points and mechanism are slightly different than the E46/3 series.

Chris

[3002 tii]

if i were replacing seats, i'd go for lightweight buckets, ie recaros. the only thing i really like about my powered seats are the fact it's heated, but don't really care for the adjustments since i don't move them once they're in place.

[ANUSTART]

@Chris, thanks for the detailed info. Looks like I twill finally be getting the Z4M seats. I'll post back impressions and details. Thanks for all the info!

[donoman]

Has anyone successfully completed this? I have manual non-heated vinyl seats in my 2003 Z4 2.5i and just purchased electric heated leather seats from a 2007.

[ANUSTART]

Donoman, you'll run into the same seat sensor issues I ran into. Still working out the details to get around it. I ordered a seat bypass off eBay while in the middle of the complex, and tedious act of transplanting my old sensor to the new M seats. So, for now, till the bypass has been proven to work or not work, the sensor swap is on hold. I'll post back how it goes, but may be after the new year.

Others can correct me, but I am pretty sure that after the facelift the sensor changed and will give you the red light on your dash when you swap seats.

Also, I posted my experience with doing the actual seat swap on another thread on here (with photos.) It's not hard, just time consuming. Run and positive and negative wire to your new seats with a fuse. Total time was about 6 hours to do, if I remember right.

[donoman]

Thanks Hog,
So are you able to run your seats with the seat bypass now? If that's the case I won't even bother with the transplant since I don't have kids.

[ANUSTART]

I don't know yet. I ordered it on Thursday and was shipped Friday. It's coming from Ireland so hopefully by end of week. But then I'm going out of town so won't mess with it till we get back. May be another couple weeks before I know for sure. I'll post back how it goes.

[donoman]

Hog, thanks...hopefully it works for you.
I'd really like to avoid performing surgery on a perfectly good seat.
Does anyone know if the seat occupancy sensor is a simple resistor? Thanks

[ANUSTART]

No worries. Here's the basic transplant diy. It is a mat that goes between the foam and leather. The bypass is a simple resistor though. http://www.z4-forum.com/forum/viewto...=23646#p331649

[donoman]

Looks like the bypass is actually a 4.7K resistor in parallel with a 1N4001 diode. Easy enough, I will try and report back... these instructions are for an E46 (http://forum.e46fanatics.com/showthread.php?t=771535)

[ANUSTART]

Originally Posted by donoman

Looks like the bypass is actually a 4.7K resistor in parallel with a 1N4001 diode. Easy enough, I will try and report back... these instructions are for an E46 (http://forum.e46fanatics.com/showthread.php?t=771535)

Cool. Would like to hear how it goes. I ordered one to save the time and pug and play, but I hear the DIY is dirt cheap to make and quite easy.

[donoman]

If you have a chance can you check the resistance of your bypass unit? Thanks

[ANUSTART]

Don't have it yet and won't till I get back home from Christmas vacation with family. Will post back.

[donoman]

I want to document my findings.

My 2003 had manual non heated vinyl seats and I upgraded to leather heated electric seats. The harness was plug and play. I do have an airbag light still as I haven't messed with the occupancy sensor. The memory function on the seat seems to work. Electric adjust worked instantly after plugging in. Heat worked immediately after I bought a console module from another Z4 on eBay for $90 with the heated seat switches. Pretty painless upgrade from vinyl... Highly recommended!