Air bag control module 2000 Z3 Roadster

[Schreier]

Hi folks,

I just inherited a Oxford Green Metallic 2000 Z3 2.3 roadster, and I just love it. A little green roadster! Such fun. Until I learned that the airbag warning light on the dash is kind of a big deal.

After reading forums and finding out it might be nothing more than pinched seat sensor wires, I thought it may just need to be reset and I could get on with my life. So I bought the Peake SRS scan and reset tool, and read off the codes. There are quite a few, and some repeat multiple times, and the tool isn't able to reset any of them.

17 Satellite, right sensor (for side airbag), comms fault or open circuit
17 Satellite, right sensor (for side airbag), comms fault or open circuit
17 Satellite, right sensor (for side airbag), comms fault or open circuit
1A Seat occupied recognition 1 (SBE1)
01 Firing circuit, driver airbag, stage 1
F0 Control unit fault, internal error
16 Satellite, left sensor (for side airbag), comms fault or open circuit
16 Satellite, left sensor (for side airbag), comms fault or open circuit
11 Supply voltage
1A Seat occupied recognition 1 (SBE1)

What should be the first course of action here?

F0 seems to indicate the whole airbag control unit is kaput. RealOem indicates the part number for the module is 65776908896, and it's $500 for an "uncoded" unit. Ouch. On the other hand, a used module can go for $25-80 on Ebay. But there's no telling of the quality, how well it would work in an accident. And would it even make the F0 code disappear, so that I could beat down the other potential issues, if it weren't coded to the vehicle?

Any advice is greatly appreciated.

[MIKYZZ4]

The first thing I would purchase is a BMW service manual for your z3, as I don't know your level of expertise on SRS systems , and would not want to be responsible if you were injured. That said, Peake is an antiquated tool, much better, cheaper options out there.

[MarcoZandrini]

The Peake SES tool is actually very good. The Peake OBD2 tool is ok as the codes are tailored for a BMW. OBDFusion is the preferred OBD2 tool.

Schreier, I'd disconnect the SES module for a couple of minutes and then reconnect it. The software may have hiccuped.

[Schreier]

Thanks guys; I think this indeed is a car that will require a service manual.

Marco, would it be enough to disconnect the battery and drain the system by turning on the caution lights, like I've read in other threads? Or do you pretty much have to pull the SES module for that to work?

[MarcoZandrini]

You could accomplish the same thing by disconnecting the ground and in the positive kit of the cables on the battery and shorting them together for about 10 minutes.

[jclausen]

The air bag control module is the main module for the system, clear all the faults and recheck

[Randy Forbes]

There is NOTHING to be gained, certainly on the Z3 platform, by disconnecting the battery; all that will serve to accomplish is losing the radio security code (which it will demand the next time you power it up, remaining silent until you do).

At some point, your car will need to be connected to a real diagnostic computer, not just for reading the trouble codes, but a new/used module WILL HAVE TO BE CODED TO THE CAR. It's not going to work right out of the box.

My advice is to take it to a reputable independent repair shop, one familiar with BMWs at the very least, and have them investigate why your light is on.

[328 Power 04]

Hi folks,

I just inherited a Oxford Green Metallic 2000 Z3 2.3 roadster, and I just love it. A little green roadster! Such fun. Until I learned that the airbag warning light on the dash is kind of a big deal.

After reading forums and finding out it might be nothing more than pinched seat sensor wires, I thought it may just need to be reset and I could get on with my life. So I bought the Peake SRS scan and reset tool, and read off the codes. There are quite a few, and some repeat multiple times, and the tool isn't able to reset any of them.

17 Satellite, right sensor (for side airbag), comms fault or open circuit
17 Satellite, right sensor (for side airbag), comms fault or open circuit
17 Satellite, right sensor (for side airbag), comms fault or open circuit
1A Seat occupied recognition 1 (SBE1)
01 Firing circuit, driver airbag, stage 1
F0 Control unit fault, internal error
16 Satellite, left sensor (for side airbag), comms fault or open circuit
16 Satellite, left sensor (for side airbag), comms fault or open circuit
11 Supply voltage
1A Seat occupied recognition 1 (SBE1)

What should be the first course of action here?

F0 seems to indicate the whole airbag control unit is kaput. RealOem indicates the part number for the module is 65776908896, and it's $500 for an "uncoded" unit. Ouch. On the other hand, a used module can go for $25-80 on Ebay. But there's no telling of the quality, how well it would work in an accident. And would it even make the F0 code disappear, so that I could beat down the other potential issues, if it weren't coded to the vehicle?

Any advice is greatly appreciated.

Oyyy, so much conflicting information in this thread. Peake tool is 'meh' at best. Very limited, and way too pricy for what it does.
Disconnecting the battery will not solve any problems on BMWs, ever. Shorting the two leads can be even worse for modules with batteries in them.


Now that I have said this...


Time to get you on your way to repair your problem. I bolded and enreddened the main fault you should be concerned about. This is also known as "Error 240 Internal Control Unit fault" by real BMW diagnostic tools. This is the kiss of death to that module, as it is a physical hardware fault, meaning an electrical component inside the module is broken. The module rejects any code clearing when this code is present. The 'airbag module reset services' you see online will NOT be able to fix it, as those are for clearing crash data disabled modules.

It can be caused when a wrong (non-corresponding) part is attached to the circuit, such as a wrong date range seat belt tensioner.
It will also happen 'out of the blue' (possibly due to shorts) on the ~03/1999 to 07/2000 Z3 airbag modules, and it is quite common with that date range revision. It is part number 65778386192. Not an uncommon problem.
BMW have superseded that part number to a new version because the old one was known to have this problem. It has happened to many users here, and to my 2000 Z3 roadster as well.

The only fix is module replacement with coding of new/used one. (This is where the expensive Peake tool is useless)

The module is located in the center console area, right below/behind the A/C controls, mounted to the chassis tunnel. You can reach it from the side, without having to remove all the center console, but you will get your hands scratched up, working in a small space.


A used module will work, but it HAS to be from the same date range Z3 (M or non M), but keep in mind that it may fault out again eventually in the same way. A new (from Dealer with superseded part number) or a used one will need to be coded (to set the correct vehicle options into it), which is fairly simple with the tools I posted in my diagnostics thread.
A module from any other model other than a Z3 will not work (no matter what the ebay part fitment guide will tell you). And it has to be from your build date range.

[Schreier]

Thanks, 328, for calling my attention to your diagnostics thread. ~$30 worth of cables and connectors to use with INPA is a much better deal than the $130 I paid for the Peake module (which only works on the airbag module). I'll post in your thread if I have any specific questions or to share any experiences.

Since you also drive a 2000 Z3, how often have you had to replace the air bag control unit? Is there some sort of long-term fix for this, or are we just doomed to drive without airbags after the control module supply dries up?

[328 Power 04]

I only had to do it once. It is not a regular replacement item. Just luck of the draw.

I think I may have caused my error when I plugged in a driver's belt tensioner that I was given (used) to try to repair a latch fault. I can't confirm because I wasn't focusing on that error, until I saw it come up.

I paid $50 for a module from a 2000 Z3M being parted out on the forums, and it has worked fine ever since (~4+ years now).

The new update (superseding part number) will probably not fault out like this.
For me, I would swap out the module multiple times at $50, but others will choose to pay the $500.
INPA easily tells you what is operational and not, in the airbag live status functions.
The coding part is quite easy if you follow my directions. Feels intimidating, but it isn't really if you follow directions. I try to be as thorough as possible.




Now if you know any really good electronics experts, I am sure they can figure out what is faulty on the module.

I initially thought it was a candidate for airbag module reset/repair service, so I bought tools to read the chip data, but it was just not possible. That's what the module reset services do; read the software off the module with aftermarket tools, erase out hard faults, and flash it back.
(The tool worked well to read the airbag modules on my other cars, as a test on VWs and BMWs, but this faulty module was not recognized at all)

- - - Updated - - -

Looking back...

http://www.bimmerforums.com/forum/sh...9#post29287829

this member's airbag module the MRS4 version from 2002 Z3s.. and it faulted in the same way. Sad to see even newer version do the same.

You and I have "MRSZ3" version 2.5 in our cars.

- - - Updated - - -

And I just updated the diagnostic thread to include how to code a single module under the "Using INPA and other BMW Tools with Z3" section

[Schreier]

After much frustration and a few broken tabs, I've been able to remove the center console and extricate the airbag control module. But I found something on the way.

z3 airbag module wires.jpg

There's two wires that definitely appear to be pulled straight out of the SES module connector. It's a blue/white wire and a yellow/white wire. Any idea what they do?
z3 airbag module wires 2.jpg
I'm concerned I'm going to have to hack up the end of this harness and wire up a new connector. Maybe the airbag control module actually is OK and just has a messed up harness?
z3 airbag module.jpg

[328 Power 04]

It's worth a try to put back together and try it. That is CURIOUS!

Your module has already been changed once. That's the superseding part number that was not installed originally on the car.


Somebody purposefully removed those pins. Very weird.

If they meant to disable the function of something, and shorted some wires in the process, then yes, the module may be damaged.

Much strangeness.

[Schreier]

Your module has already been changed once. That's the superseding part number that was not installed originally on the car.


Somebody purposefully removed those pins. Very weird.

Curious indeed! Changed module, pulled pins. Interesting.

I made good use of my PDF copy of the official BMW electrical troubleshooting manual for the car. Here's what I found on page 133, the Supplemental Restraint System.

srs cm 133.jpg

I'm looking for white/yellow (WS/GE) and white/blue (WS/BL) wires. Well, well. What do we have here? Some white and yellow and white and blue wires!

bmw z3 srs drivers passengers side impact sensor.jpg
They go to the driver's side and passenger's side impact sensors, respectively. And just what kind of error codes did I find with the Peake tool?

17 Satellite, right sensor (for side airbag), comms fault or open circuit
16 Satellite, left sensor (for side airbag), comms fault or open circuit

So that potentially helps me out quite a bit. My thinking at this point is that there were some kind of faults in the left and right side impact sensors, and someone thought it would be better to pull the wires for the two sensors than to fix the actual issue. May or may not be related to the fact that the SRS module was replaced at some point. But I do know that this car has only one previous owner, who is deceased, and the car has a clean Carfax with no accidents reported.

Who knows, but my goal right now is to get it as close to factory as possible to sort out the airbag issues. I'm hoping I can manage to get those crimps back into place in the original connector. I've got a replacement SRS module on my porch right now waiting for me to come home and plug it in. I've also got a USB to OBDII cable that should arrive today, that I intend to use with my new INPA installation to pull codes from this Service Engine Soon light. Fun times.

Short of tracking down a 2000 Z3 in a salvage yard and hacking out the airbag control module harness, anyone know how to acquire one? I could find no part number or diagram on RealOem for such a thing. I could find nothing on eBay. Nothing through Google. The most I could find out is that the actual connector is called an X74, apparently may still used in BMWs. But it's a 50-pin connector but not all pins are used and there's probably a crazy amount of variation in the cable configuration.

[328 Power 04]

I think you should be able to put those pins back in just fine.

Strange repair attempt by them... As it would never work.

[LannVouivre]

This is also known as "Error 240 Internal Control Unit fault" by real BMW diagnostic tools. This is the kiss of death to that module, as it is a physical hardware fault, meaning an electrical component inside the module is broken.

I've been getting an intermittent airbag light, so I borrowed my old boss's Solus Pro to pull codes. Got the F0 internal fault code. Guess I need to locate a replacement at some point.


Anyway, I have ProDemand open to TSB 72 04 00: sensors for side airbags, mrs 3 fault codes 16/17

1. says if airbag control unit is 65 77 8 386 192, replace with 65 77 6 908 896
2. says that if impact sensor wires (pin 20 white/blue, pin 21 white/yellow on X74) are not a twisted pair, replace with PN 61 10 6 914 295
3. says if the 896 module is installed and the satellite sensors have twisted pair wires, replace the affected airbag sensor with 65 77 6 454

[328 Power 04]

That's good info!

[Schreier]

I've been getting an intermittent airbag light, so I borrowed my old boss's Solus Pro to pull codes. Got the F0 internal fault code. Guess I need to locate a replacement at some point.


Anyway, I have ProDemand open to TSB 72 04 00: sensors for side airbags, mrs 3 fault codes 16/17

1. says if airbag control unit is 65 77 8 386 192, replace with 65 77 6 908 896
2. says that if impact sensor wires (pin 20 white/blue, pin 21 white/yellow on X74) are not a twisted pair, replace with PN 61 10 6 914 295
3. says if the 896 module is installed and the satellite sensors have twisted pair wires, replace the affected airbag sensor with 65 77 6 454

I'm sorry to hear about your F0 code. Thank you for contributing this info, very important! I'll take a closer looksie at what I've got and report back. Any chance there's a TSB on what to do for a code 11, supply voltage?

Thanks again!

[328 Power 04]

Supply voltage is a code that is usually historical for low battery. When module is operational (meaning sans Internal Ecu Fault) it clears just fine.

[LannVouivre]

That was the only TSB for the SRS system that I found besides generic service info that applies to all BMWs.

[Schreier]

An update

Initially, I was concerned that I'd have to do some surgery of the X74 connector to get the wires for the left and right impact sensors. But lo and behold, there's a simple little white retaining clip on one of the ends of the connector that slides up and out. Once you slide the white clip out, you'll see that the actual connector is hidden under a yellow cover, and it's also possible to slide that cover out. Then you get a clear view where the wires go.

_DSC2843.jpg

_DSC2844.jpg

If only my issue were as simple as plugging the two wires back in to the proper location. As it turns out, both those slots were already occupied by other wires. Pin 20, the driver's side impact sensor, had a solid blue wire. The very next pin down, the passenger impact sensor, pin 21, had a solid yellow wire.

_DSC2847.jpg

So, to recap: the SRS module isn't original. The original driver and passenger impact sensor wires have been pulled. These wires have been replaced with other wires. The SRS module matches the replacement specified in the TSB.

I suspect that these yellow and blue wires are the twisted pairs in the 61 10 6 914 295 kit, and that if I pull the doors apart I'll find the 65 77 6 454 impact sensors. That would be the responsible thing to do, tear down the doors and investigate. What I did instead was plug in a replacement SRS module from a wrecked 2.3 to see what happens.

When I did that, I got the following codes:
01 Firing circuit driver airbag
02 Firing circuit belt tensioner
06 Firing circuit side front right
0d Firing circuit driver airbag stage 2
16 Satellite left sensor
11 Supply voltage
0d Firing circuit driver airbag stage 2
05 Firing circuit side airbag front left
14 Seat buckle belt switch
03 Firing circuit belt tensioner

That was with the Peake tool, and INPA showed an additional fault for the accident stored in memory. Ok, as much was expected from a wrecked car, though luckily no "internal fault." But I didn't expect the next thing to happen. I went through the normal coding steps for the module as described in the Z3 diagnostics thread, and what were the results? Still had SRS light, but only two codes showed in INPA: left and right impact sensors. Nothing about an accident stored in memory.

Did coding erase the crash history? Dunno, I'm no electrical engineer. Not saying that this is a real fix for an SRS system fault. All I know is that I've driven the car at least 50 miles like this, and the fault has not returned.

At any rate, will need to tear down the doors and take a look at the impact sensors eventually.

[JoshS]

The impact sensors are not in the doors, they are under the seats.

- - - Updated - - -

If it helps, I have a 65 77 8 381 564 sensor sitting around that you are welcome to.

[Schreier]

The impact sensors are not in the doors, they are under the seats.

Well I'm very glad not to have gotten into the doors to look for that, then! Are they attached to the actual seats? I'd be very thankful for any posts/diagrams/photos on it.

If it helps, I have a 65 77 8 381 564 sensor sitting around that you are welcome to.

That would be very generous; I'll keep that in mind

[JoshS]

Well I'm very glad not to have gotten into the doors to look for that, then! Are they attached to the actual seats? I'd be very thankful for any posts/diagrams/photos on it.

If you remove the seat and pull up the edge of the carpet at the split you'll find there, you'll find a horizontal/lateral frame rail running across the car. The sensors are mounted to the edge of that rail, just behind and inboard of the front outer seat bolt. Can't miss it :-) Best pic I could find (this is someone else's car, not mine, just went through my stash of Z3 race car cage photos). It's the small black thing with the yellow plug. Although this car is obviously well-gutted, I'm pretty certain you could get to this without doing any more disassembly other than removing the seat.

IMG_0015.JPG

[Randy Forbes]

With any luck, yours won't look like this one...



... and though still not pristine, this one is an order of magnitude better!

[328 Power 04]

This thread is filled with quality information. This will help through the decades.