Brent Weight

My 200 Suburban airbag light comes on and stays on when it is colder. When warm, it doesn't stay on. Sounds like some sort of wiring issue.
I took it in to the dealership. They scanned it and the code is b0028, front passenger side airbag low resistance. Their service notes says the circuit to the SDM module is good and the airbag needs replaced. They wanted $1100 to do that.

I went and pulled an airbag at the junk yard. Appears to be in good shape. Plugged it in under the seat and the light still stays on. I guess the module could also be bad, but I doubt it and not eager to spend $1100 to find out.

Any ideas on how to further troubleshoot this? Are there any other sensors that I should be checking? I would even settle for a way to bypass this one airbag.

If the airbag light is on, does that mean that ALL airbags are disabled or would it just be the passenger side airbag? I'm not comfortable driving the car without any airbags.

Any help is appreciated.

kevinkpk

No where near an expert in this field, but general troubleshooting I would look at the seat sensor. Low resistance to me sounds like the sensor is "worn out". I am gauging this on passenger side air bag with no passenger, and getting the message, but on the driver side.

tech2

they test the system using a air bag load tool. the tool simulates the airbag resistance. the sdm is looking for a set resistance...when the resistance is out of spec a code sets. the tool is plugged in place of the airbag...if the code goes stored, the faulty part has been removed..air bag. if the fault is still present the load tool is plugged in at the next connector closer to the sdm. this is continued until the fault goes away.
they use the load tool as this is safer than checking wiring with a ohmeter...ie current from the ohmmeter causing deployment.

the fault can only be in the airbag, wiring, wiring connector or sdm.
you can only perform diagnostic testing on the system when the fault is active. if the fault is not active the system will test all ok.



if the airbag light is on...the complete system is disabled.

Brent Weight

I am assuming that they did this and that is why the indicated the wiring to the SDM and the SDM are ok, but the air bag is not. Yet when I plugged in a different air bag, I got the same code.

I am assuming based on the fact the light is on when cold and off when warm, that the code is not permanent and if the airbag system is ok, the light goes out. That assumption leads me to believe if I switched out the airbags and it was good the light would go out and the code does not need to be removed with a scan tool. Can anyone confirm?

I used the connector under the seat where the airbag itself plugs into the harness. Perhaps they tested it at a different connector. Where does the hardness go that starts under the seat? Does it end up in the dash or somewhere else?

Anyone know what resistance they use to simulate an airbag? I could make my own tester to see if I could troubleshoot it. I know you aren't supposed to measure the resistance directly with an Ohm meter.

Brent Weight

Do you happen to know where this seat sensor is located?

tech2

hard for me to know what you are doing without pics. why are you going into the seat when the fault is for the passenger dash airbag? are you sure you are connecting into the correct loop?
2.2ohms

Brent Weight

It is the passenger side airbag in the seat, not the passenger front airbag. So it is in the seat or the harness that is leading to the seat. I just don't know where the harness that is in the floor right below the seat connects to in the rest of the car.

Where is the SDM in this model? Perhaps it goes directly there.

tech2

after you plugged in the replacement...do you have a scan tool to clear out the old fault code from the sdm. Not 100% sure but without a scan tool it may take 40 key cycles of test passing to clear without a scan tool.


can you not remove the seat back cover and follow the wiring from the airbag to the connector.
if the replacement air bag is good... use it as a load tool....plug it in moving forward in the harness until the code goes stored. or make a load tool with a resistor and old connector.

Brent Weight

I don't have a scan tool. I'm not sure if I need one because in the late afternoon, when it is warm, it starts without the airbag light being on. It only turns on when it is cold. That tells me that the code comes and goes without needing to be cleared, but I would love someone to confirm.

The wire from the airbag down to the seat is not very long and I have that wire harness on the "new" air bag. It is hard to get into the actual seat back. I need to figure out where the next connector is moving towards the air bag control module. It goes under the carpet but I have no idea where it ends.
Working on getting the right resistor to make my own load tool.