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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > DIY Guides > DIY Powered seat retrofit (WIP)

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      12-13-2023, 03:12 AM   #507
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Hello, I have got a E90 2007 320I with heated seats and i want to swap them to sports powered memory seats which i bought from E92 335I for very good price. Can someone suggest what diagram i need to use to complete this task?
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      12-15-2023, 11:58 AM   #508

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Originally Posted by Red Racer View Post
BurtDiesel / 4EST...

The LED module I originally used started to give me issues. So, I went back and re-worked the solution. I started with a timed relay module...


This allowed me to program the relay to turn on for 3 sec and turn off for 3 sec. I found that at 5 sec, then 4 sec intervals didn't re-activate the seat module. 3 sec seems to work continuously. It also gave me a higher amp rating which is where LED relay was failing.

Keep in mind this relay module is for 12v options and the seat only likes 5v. So, after the relay, I reduced the voltage to 5v by using a common Buck regulator set for 12v to 5v. There are many options out there... This is the one I picked.


Now the seat works continuously without any issues. Hope this helps.
Can you post what products you used? The amazon links are dead, interested to see what timed relay module you used.

Originally Posted by Red Racer View Post
Retrofitting E90 Seats into a Hot Rod or other car without a computer (KCAN).

Just wanted to add to this great discussion. I have been reading this for over a year while I build a 1968 Mustang Fastback. I have a set of 2008 M3 seats in dark red that matches the cars Shelby strips.

Obviously, the car does not have a KCAN signal or feed to keep the Driver's seat activated. I have been searching for a solution for quite a while and I think I found one...

I started with a 5v source @ 1-2 amps to trigger the KCAN feeds into the seat.

1st test included simply touching the wire to the feeds in the seat...result: seat worked for about 30secs to 1 min. By disconnecting and reconnecting, I was able to get another 30secs to 1 min.

2nd test, I found a common LED power source for retrofit automotive tail lights. It dropped the 12v feed to 5v - LEDs dont need full power. So by using an early mustang retrofit module where the LEDs sequenced to turn on each individual light bulb as the turn signal is activated, (the new mustangs, this feature is built in) I created a pulsing 5v signal. Low and behold, I found / created a signal that the seat saw as a KCAN Signal.

Result... the seat worked continuously while the ignition was active. All the other functions work when wired as others here have described.

What is the LED power source for retrofit automotive tail lights that you are referring to, is it something like these?

Sequential LED retrofit kit?

Generic LED controller:

Last edited by Red-Duc; 12-15-2023 at 12:12 PM..
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      02-10-2024, 03:44 PM   #509

Drives: BMW E34 525i
Join Date: Feb 2024
Location: Illinois

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I have E90 seats from a 2011(Power,Heated, W/ Memory). I can't get any movement from the drivers seat.

I have 12V+ to pin 4 (large red) and 12V- to Pin 8 and 13 (large brown). The seat won't move even for a second. Lumbar works though.

I have also tried 5V+ to Can_H and 5V- to Can_L. Still no movement.

Anyone know how to get the drivers module to wake up? All the other modules I've seen are black, mine is white. Is this related to the later model year or related to memory seats? Anyone successfully been able to bench test the memory seats without being installed in a car?

Last edited by at-jefft; 02-10-2024 at 11:28 PM..
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