2003 325i airbag warning light

[2mbb]

My son has a 2003 325i. The AC blower stopped working so i replaced the blower resistor this weekend. Well the blower now works, but I have the airbag warning light on. When I start the engine it blinks once (when the warning lamp testing period ends) but the warning light then stays on continuously. I have an Innova scanner that will read SRS faults and it gives me code 50 "The DTC Definition is not available" and code 05 "Resistor ZK3 --> Passenger airbag". To replace the blower resistor, I did remove the glove box, upper kick panel and an actuator housing that covers the resistor. I also moved the passenger seat all the way back and reclined the seat. Afterward I looked under the seat and didn't see any disconnected plugs or notice anything problematic. All the under seat wiring was tucked up and secured to the bottom of the seat.

any ideas where to start looking?

any recommendations on a scanner that will give better codes and reset the airbag warning light?

Thanks.

[E39 Newbie]

First, check to see that the battery is good and that the charging system is working correctly.

I pulled the following from another site. I assume it's reasonably correct.

http://www.unofficialbmw.com/images/...lure_Codes.pdf

From the description of Error 5, you may have disconnected something/broken something, while under the dash replacing the resistor. Check all your fuses, then try following the diagnostic procedure.

Did you disconnect the battery before replacing the resistor?

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No, I didn't disconnect the battery. I watched some youtube how to do it, and they didn't disconnect the battery--haha. maybe my bad.

Since the COVID we haven't be driving the cars much. In the past year I've had to replace batteries on two other cars. This one also has a slow crank, so I'll check the battery voltage too. Thanks!

[MarcoZandrini]

It’s a good idea to remove the negative cable from the battery whenever yo mess around the airbags. The SRS system is rather sensitive to voltage swings.

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Yes I do disconnect the battery when I am removing or uncovering airbags. I was replacing the AC blower resistor and wasn't planning on effecting the airbag. Live and learn.

I did the first test associated with the code 05 troubleshooting from the link posted above. I tested resistance between the pair of wires that go from the passenger air bag back to the air bag control module. The resistance was within spec. My air bag actually has four wires (two pairs) going to it. I read someplace that after 1999, single circuit airbags were replaced with dual circuit. The resistance for each pair was within spec. My interpretation of that trouble shooting sequence is that if the first test works (resistance of the pair of wires at wiring harness connector at the airbag) is OK, then I don't need to do the remaining test; the remaining tests will locate a problem but are not needed if everything is OK. Am I understanding this correctly?

I measured my battery voltage (car not running) and it was just under 12VDC. I think my next step is to reset the codes and see if they come back.

Thanks.

[harrier]

There is a clip for the passenger airbag behind the dash above the glovebox. I would make certain you didn't break the connector. It has a funky clip that has to be engaged for the airbag to work and not throw codes.

Also, do you have a tool to reset the light?

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I have a reset tool out for delivery today, hopefully.

Since the original problem, I have pulled the passenger side air bag and disconnected the bag from the wiring harness. The wiring harness side of the connector is mounted to the dashboard. Is this what you are talking about? Or is this a clip associated with mounting the air bag?

I did try to see if I could un-mount that side of the connector, but couldn't easily figure out how to do it. So I just left it mounted to the dash as I checked the resistances between the pairs of wires, back through the air bag control module. Or is this a clip associated with mounting the air bag?

Thanks for the help.

[2mbb]

Sorry it's taken so long to give an update. I finally got to try out my new OBDII scanner with air bag reset capabilities. The strange thing is, one of the codes was for the left side (drivers side air bag), so I'm not sure why my meddling with the AC blower resistor on the passenger side would influence this. Anyway. I reset the codes and the faults went away and haven't come back yet. Hopefully this will take care of it for now. Thanks for all the help! On to the next project.

[ekjdm14]

Sounds to me like it was low-voltage related. anything under 12v suggests a battery fully discharged (fully charged = around 12.6+, 12.4 or below really needs a charge).

If the battery can't maintain a voltage of over 12.5 standing for a few days after being fully charged, I'd suggest it's past it. (although many "dead" batteries from modern cars are still perfectly fine for use in older vehicles with less/no computers since they'll still put out the amps to spin the thing over, so perhaps this one could be "retired" to something older in your stable)