Seat Module, my $5.90 'fix'

[Showtime]

Awesome. Thanks again for your response

[llawes]

holy schematics batman!!!! nice write up bro!!

[wpoll]

Amen to that - awesome work!

It's this sort of thing that make owning (and working on) the e53 such a joy - later cars are getting so complex that very few will go this far down the rabbit hole...

[iansanderson]

I'm really happy you made this post RDCX5! I have been banging my head against a wall for two years over my passenger mirror reverse dip on my '04 E53.

In the E53, the SM controls exterior mirror recall for seat memory, and reverse dip. My passenger mirror goes where ever it wants into and out of reverse. Sometimes it dips halfway down, sometimes it stays pointed at the road and doesn't come up. Today, I kept pressing memory 1 and the mirror would move all over the place even though I wasn't adjusting it. I have replaced almost every part of the mirror control system to date: mirror drive, general module, driver switch module, passenger switch module.

What I have not replaced was the seat module. What you wrote totally makes sense. The amount of read/write cycles the (now 16 year old) CPU takes for something like mirror memory is probably the culprit considering every X and Y adjustment, reverse dip, seat recall, uses the CPU memory. The passenger mirror data is probably no longer being recalled correctly from the CPU causing the erratic behavior. The new SM will be here in a few days, and I am hopeful it finally fixes it!

[RDCX5]

Welcome. Have you checked the variable Resistors in the mirrors? They get used as position 'sensors' and if they are gunked up or have gone bad they would report all kinds of erratic data for the actual position of them causing all manner of weird issues like that as well.



https://xoutpost.com/bmw-sav-forums/...d-writeup.html

[iansanderson]

Originally Posted by RDCX5

Welcome. Have you checked the variable Resistors in the mirrors? They get used as position 'sensors' and if they are gunked up or have gone bad they would report all kinds of erratic data for the actual position of them causing all manner of weird issues like that as well.



https://xoutpost.com/bmw-sav-forums/...d-writeup.html

I actually replaced the motor assembly new from BMW on my very first attempt to fix it, same issue. I even wired the motor twice thinking I made a bad connection. The last straw was the power folding mirror I just installed yesterday, and it's acting identical to my old one. I'm at $1K (parts) into this issue, and unless there's some crazy wiring issue that I haven't found, the new SM should do it. There's literally nothing left to replace except the car

[iansanderson]

Update: The new seat module fixed it! Talking with a BMW tech friend, he said there is a similar issue on the newer models' FRM module, where the CPU inside goes bad from too many read/writes. Thank you RDCX5 for the research and the post!

Part number is 61 31 7 119 867, retail $407.90, $305.92 with discount

[RDCX5]

Welcome, glad to hear the info helped and that sorted it for you.

[amancuso]

Originally Posted by iansanderson

Update: The new seat module fixed it! Talking with a BMW tech friend, he said there is a similar issue on the newer models' FRM module, where the CPU inside goes bad from too many read/writes. Thank you RDCX5 for the research and the post!

Part number is 61 31 7 119 867, retail $407.90, $305.92 with discount

And this is why I am not going to replace mine for a mirror dip issue. I rarely parallel park anyway. To stop the mirror from misbehaving, I just leave the mirror switch to passenger side to stop it from dipping. Problem solved, and it was free. ;-)

[upallnight]

Originally Posted by iansanderson

Update: The new seat module fixed it! Talking with a BMW tech friend, he said there is a similar issue on the newer models' FRM module, where the CPU inside goes bad from too many read/writes. Thank you RDCX5 for the research and the post!

Part number is 61 31 7 119 867, retail $407.90, $305.92 with discount

You could have bought my two front seats for $100.00 and taken out the module from the driver seat for a lot less.