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Discussion Starter #1
1998 continental T Vin 67067 RHD in South Africa. Total mileage 20,000 km/12400 miles so as new.
Most of the driver's seat movements have quit working. Only the rake is working. I removed both seats thinking that there is an issue with the memory battery leaking on the printed circuit to find that there is no battery. The memory module is BMW #8356510 which has a flash (eprom) memory.
In the first instance I intend checking all the motors for functionality. The wiring and contacts all look perfect, the seat has been out before but I have no idea what the problem was. I have a family acquaintance who is an electronics expert and I intend taking both memories to him to check out. The printed circuits both look undamaged.
Are there any circuit diagrams available for the memory modules? Any advice please will be appreciated.
Thanks Robert
28885
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Most of the driver's seat movements have quit working.
This being the case focus on the switch. Try cleaning with electronics cleaner. The BMW seat control units are close to bulletproof. Since they are the same part # you can try and exchange sides.
 

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Agree with JR2 I just saw message. Make sure it is not a plug , exchnaging is an excellent way to test

1998, yes you have BMW seats so different than 97 and previuos

My only advice would be to contact the besty specialist I know in Europe, who is in UK and knows very very well all the electronic on those cars.
I am sure they know those BMW ECU too as they are electornic engineers working for Crewe directly for more than 40 years for John.

Contact Graham

[email protected]

Bowling Engineering Ltd,
Unit 5 Fishbrook Ind Est,
Stoneclough Road,
Kearsley,
Bolton BL4 8NF
Tel 01204 862500.
 

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Robert - did the motors click each time you pressed the button but no fore aft movement? If it wasn’t total failure out of the blue It is worth checking the drive cables as they cause the seat to totally seize up. google any bmw of the era given your seats are from a bmw 8 series (e31).
I worked on a 2000 conti T at 15k miles where the outboard side of the seat had small movement and the inboard zero which was a cable issue. its worth you doing given the seats are out as it’s very easy.

lastly while bmw e31 coupes are quite rare in SA its worth seeing if you can source a seat module/cross reference the part number to try a plug and play.
 

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Discussion Starter #5
Hello all,

Many thanks for your various replies/advice, much appreciated. I will be tackling the seat project in the coming week or two. First need to complete 2 other car jobs. I googled the BMW E31 seats and obtained considerable good information regarding the cables. I will advise my findings in due course.
 

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Those control units fit many vintage BMW's. Should be easy to source if needed in SA.
Looking at the training manual it shows that the seat control unit has three sources of fused power.
It would be wise to check and see if you have power at all three leads and if so that the voltage is the same at all three.
Here is the link to the manual:
Seat training manual
 

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Discussion Starter #7
Report back on seats:

Memory units checked out ok, no relay or circuit problems.

Seat motors all running perfectly, the problem was with the drive cables. They all needed lubrication, in particular the forward and aft ones which are used the most. Biggest problem was inner cable windup maybe due to friction resulting from poor/nonexistent lubrication. This meant that the cables became shorter resulting in not connecting with the motor. As per the RR/Bentley forum recommendation, Using a heat gun, I heated the metal ferrule at the end of the plastic casing, cutting about ½” – ¾” off the casing and refitting the ferrule using heat. In this way the cable protruded further out of the casing and problem solved!

Lubrication also made the mechanism quieter with less strain on the motor. Very pleased that all seat functions now working perfectly!
 
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