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Old 05-20-2011, 02:27 AM
AceFX AceFX is offline
Location: I come from the land down under
Join Date: Mar 2011
Posts: 1,248
Mein Auto: BMW 760Li BMW X5 4.8iS
SZL CAN BUS errors on my 2003 760Li

Hi all 7 owners. I have a major problem that has had my car off the road for five months now.

Originally I had DBC, DSC, ACC, SZL errors.

I went to a BMW Dealer and they said cats were 50% blocked. They said replacing cats would fix all the faults as the car was in limp home mode.

$7,900 later I picked up my car on Saturday morning from the BMW Dealer and the car was fine. My V12 had unbelievable power again.

Then after about 1 hour of driving, the trans errors started to appear again but no DSC or DBC.

“Gear position N only when engine running”
"Transmission fault" and "Drive moderately"


ACC Failure……the dealer thought the faulty brake light switch was the problem.

So the Transmission faults and the ACC faults were continually coming up.

Then I got the worst warning….”Transmission Failure” …..

The transmission faults always seemed to start when the car was stationary…..does that mean anything or help???

Well, the funny thing was though that the car was driving fine, changing gears nice and smoothly . Didn’t lose power and the car remained quiet and quite drivable, no problems other than the annoying alarms continually going off. Even with the “Transmission Failure”, the car still drove perfectly.

Well I went back and they reset the errors for the trans.

His device was reporting the following….

51AC No message(identification sensor connected) from engine management
5147 No CAN message from SZL

It also reported that the Brake Fluid sensor switch is faulty. RED car on the display warning symbol.

Also the Windscreen Washer Water was reporting empty even though it was full, and the Boot will not open properly and the lid wont stay up, it kept falling down, wouldn’t lock upright.

But after they reset the errors, after a few moments, they came on again whilst his device was still connected…..the engine was running whilst he had his device connected.

Could it be the alternator causing problems? I have read about this on the bimmer forums.

I also read somewhere about a faulty wheel sensor upsetting or confusing the trans????? One of the front struts has been replaced, would that be something???

On the forums they also talk about trans oil levels etc too???

So I headed off home with the alarms going off every 30 seconds or so, hoping that a run would charge the battery and all would clear.

No such luck. Problems got worse. I was 70km’s north of Melbourne at the BP Service Station.

Whilst stopped after getting fuel, the windscreen wipers started operating and I couldn’t stop them. Then the Airbag and Seatbelt tensioner warnings went off and the dash turned red with those alarms. Then the Trans errors, ACC errors, it was all happening at once. The car was going nuts.

Interestingly, the ACC would sometimes work fine and then other times fail every 5 secs…….it’s fault is definitely intermittent, but it was more faulty than working.

I returned the car back to the dealer to be looked at again.

I just remembered one other odd event. Sometimes whilst using the iDrive, the menu would keep going back to the main menu screen, like it was not responding to the commands I was giving it and just kept jumping back to the main menu screen??????

The SZL unit has now been replaced twice in one month and also the battery has been replaced twice (genuine BMW AGM Battery done at the dealershiop both times) in the last month. The first new battery died with two dead cells when it was only one week old????

PLEASE HELP because my BMW dealecant seem to fix it and he has had my car now for five months.

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