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turbolizard

e39 M5 airbag control unit

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My airbag light is on and INPA gives the following error codes.

I beleive the first error in the list (240) indicates that the control module needs replacing but before i do I would like to confirm if it was killed by the belt tensioner, or if these other errors may be false due to a fault in the control unit.

For context - I have previously had false detections of sensor faults in the ABS system when it was actually the DSC control module that was crapping out.

Can the belt tensioner be independently checked?

Date: 12/08/15 08:14:30
ECU: MRS3
JobStatus: OKAY
Variant: MRS3
-------------------------------------------------------------
RESULT: 3 errors in error memory !
-------------------------------------------------------------
240 Internal ECU error
Error frequency : 1
-------------------------------------------------------------
3 ignition circuit ZK2 -> belt tensioner passenger
Error frequency : 1
error not active at the moment
battery short circuit
error is not sporadic
-------------------------------------------------------------
3 ignition circuit ZK2 -> belt tensioner passenger
Error frequency : 6
error not active at the moment
short to ground
error is sporadic
=============================================================

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there is a model of these built around 1999-2001 etc that all seam to be failing now

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The part number on mine is 65776900727 and a search of the web seems to suggest it is one of the troublesome modules you mention. Therefore, at the very least I need a new control module. Is there any way to determine in advance if the error codes about the belt tensioner are legitimate or just part of the module failure?

Thinking about the control module now - looking on Real OEM I see that there are a number of supercessions of this part....

65776900727 is... Superseded by:
65776910676 (01/01/2001 — 09/26/2001) , nonexchangeable retrospectively
65776920848 (08/29/2001 — 04/12/2002) , Exchangeable retrospectively
65776919789 (02/25/2002 — ) , Exchangeable retrospectively

If I get one of these (retrospectively exchangeable) later modules with the newer part numbers (or if I get a working but different version of 65776900727) I assume it can be reprogrammed to suit the number and location of the airbags in my car. Is that right?

Mike

Edited by turbolizard

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Mike - are they hard faults? - can they be cleared?

Also check ign switch. Faulty contacts on acc circuit will trip air bag circuit faults. Been there!

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I can't clear the airbag faults.

INPA seems to read them ok but when I try to clear them I get some sort of error message....

[Job status Error]-ECU rejected Instead of OK! Continue running scripts? <--something like this

I replaced the ignition switch some months ago, which solved a bunch of random behaviour. Airbag fault turned up later, but I do also have a fault with ABS/DSC module at present (previously had this repaired but it is flaky again and out of stock at maf-shop.com).

I love this car but the electronics are driving me crazy right now. Wish it worked like my e34, which seems very robust.

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Does anyone have an airbag module for sale with one of the following part numbers (in order of preference)...

65776919789 <--this one probably best as is the most recent (and hopefully more reliable) part

65776920848

65776900727

The modules with part numbers above are for two stage airbags as used in 7' e38, 5' e39, Z8 e52 and X5 e53. If it is from a different model I beleive I can code it to the car ok using NCSexpert.

The part number on mine is 65776900727 and a search of the web seems to suggest it is one of the troublesome modules...


Thinking about the control module now - looking on Real OEM I see that there are a number of supercessions of this part....

65776900727 is... Superseded by:
65776910676 (01/01/2001 — 09/26/2001) , nonexchangeable retrospectively
65776920848 (08/29/2001 — 04/12/2002) , Exchangeable retrospectively
65776919789 (02/25/2002 — ) , Exchangeable retrospectively

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How did you get on with this?

Did a new module clear the other codes?

I've got the F0 internal error showing on my 750i so cant clear the codes at all. Looks like I'll be needing to get a new module coded to the car.

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So far it is not solved.

First, I got hold of another '727 module (same part number as mine, but from an e38). I could talk to it using INPA and could code it with e39 settings using NCSexpert, but it had the same 240 Internal ECU error as my original '727 - it was therefore also dead and error codes could not be removed. Brent warned me that it is hard to find a living version of the '727.

I then bought a '789 module, which is listed in RealOEM as a retrospectively compatable supercession of the '727. I could code this module and could clear fault codes, but when I start the car I get four fault codes back (which I can clear, but reappear when I restart). The codes I get now are inplaussibility codes and the original (possibly bogus) codes have not returned. I think the coding issue I have now is something to do with the move from MRS3 ('727) to MRS4 ('789) as there are some differences in the data for these modules. I used the default settings from the VIN number in NCSexpert, so it may not be recognising that I now have MRS4.

I need to do further investigation but for the moment I am driving my more reliable US made vehicle, or my older more reliable German vehicle. It is just as well for my mental health that I think of this as a hobby!

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