Diagnostic tool for 2002 BMW 318ci - e46 engine

adocholiday

Hi all,

I have spent ages looking online and am completely confused as to what I need. Basically I have an airbag light on constantly that is caused by a faulty sensor. I need to diagnose what sensor it is, replace it, and then reset the light.

There are so many different tools, 20 pin and 16 pin connectors, different software... and I've no idea what to get. Can someone please tell me what exactly I need for this?

jimgoose

The problem you're going to have is that those SRS systems tend to be outside of OBD-II core powertrain, and probably can only be read by manufacturer-proprietary diagnostic equipment. There are numerous tools available on eBay for resetting the airbag light, but you say you want to do some actual diag-and-repair. Have a look at the wiring looms under the front seats - bad connections/wear in these often causes SRS problems, as it is usually here that the seatbelt pre-tensioners are linked to the airbag system. Failing that, I'd try to find an independent garage with BMW diag capability.

deandean

You can buy an airbag-specific code reader & reset unit, here is a link to one, also check ebay etc:

http://dx.com/p/b200-bmw-airbag-srs-scan-reset-tool-35188#.UyBH7j9_sao

Idbatterim

its probably the seat occupancy sensor, I think its usually the passenger side, if this is the culprit, you can by a bypass sensor on ebay for a few euro...

Nforce

Back when I had my E46 I used INPA Ediabas diagnostic software.

adocholiday

Thanks for the replies everyone. One of the key things is that I don't want to just bypass it, I want to actually fix it. If it's faulty the airbag may not actually work so I'm not taking that risk. Nforce do you know if that software can work with the SRS? Also what is the interface between the car and the computer?

Nforce

IIRC it could interface with the SRS system too. It worked via the OBDII port requiring a laptop with an RS232 port in order to work correctly with the software.

adocholiday

Nforce wrote: »

IIRC it could interface with the SRS system too. It worked via the OBDII port requiring a laptop with an RS232 port in order to work correctly with the software.

Thanks that's great! One last thing, do you remember what kind of cable it was? That would be everything I need then!

Nforce

It was a little electronic box that connected one end into the OBDII port on the car and the other end connected to an RS232 port on the laptop.

TBi

If it's the occupancy sensor then there's no harm in bypassing it. It just means the passenger airbag will go off in an accident, even if no one is sitting there.

Two resistors, a diode and some soldering skills are all you need. Very cheap fix!