2004 2.5i Driver's Seat Issues

[jwjjr]

I am relatively new to BMW ownership. I've got the 2004 Z4 e85 2.5i convertible manual transmission. It has several issues, but one that bugs me is the driver's power seat. It works when the car is off, but not when it's running. The passenger seat works fine. I spoke to my BMW dealership about it possibly being a safety issue, but they had never heard of such a thing. Is there something i'm missing that will allow the drivers seat to be adjusted when then engine is running?

[Muzz258]

Welcome to the world of BMW ownership. A few things to help set you up:
- NewTIS for wiring diagrams and service information https://www.newtis.info/tisv2/a/en/
- Real OEM for part numbers and exploded diagrams www.realoem.com
- Have you got a good scanner with BMW software so you can read the trouble codes in all modules? Its recommended that you get one, saves money in the long term and helps you understand your car better. There are lots of option, here are two

INPA software (free) on a laptop with special cables (cheap) https://www.bimmerforums.com/forum/s...xperimentation

Foxwell NT530 scanner with BMW software https://www.foxwelltool.com/wholesal...installed.html

Once you get your scanner, check for trouble codes in the seat memory module.

Lookup the seat memory module in the wiring diagrams in NewTIS and see how the power supply is feed to it. Is there anything that might change when the car is turned on?

[JAS1169]

I honestly can't see how OEM power seat wiring could result in your power on/power off seat issue. However, I then realized that this could happen if a prior owner intentionally altered the electrical system. In that, I'm guessing here, that a prior owner wanted to hardwire a device into the car and need a power line and chose the power seats because it is always on. The new power line to the device was installed with some kind of diverter which allowed power to flow to the seat when the car is off and then diverted the power to the device when the car was running. I would also strongly suspect that this type of modification would have been done by a professional installer. I guessing that the device is long gone with the prior owner. However, the modifications made to the car remain and result in your odd seat power issue.

I may be 100% wrong, but it's the only logical answer I could come up with for something that shouldn't otherwise be happening.