Airbag Light on and Code B1000

Started up the truck yesterday to find my airbag light on. I tried multiple restarts in the driveway, but it remained. It stayed on all day and is still on today.

My OBD code reader shows code B1000 - Airbag ECU Malfunction.

I haven't done any sort of work/mods to the truck in several months; this issue came out of the blue.

I have unplugged/replugged the steering wheel airbag and both airbag connections under the seat. No change.

The only other symptom that may or may not be related came up last night. I started the truck, and it immediately started beeping at me to shift into Nuteral and was flashing the 4LO light. I had not touched the 4WD selector; it was in 2H still. This went away with a restart.

Does anyone have any starting places on how to diagnose the B1000 code? Should I remove the center console to get down to this piece and check the wiring at the source? I have an appointment at my shop for Dec 1, but I would like to resolve it myself if possible; I don't love driving around without airbags.

 

Fixed. I had to remove the entire center console and AC ductwork for the rear seats. I unplugged and re-seated the Airbag ECU, and the problem was corrected. I will update you if it returns. Plug J46 in the plug below. There is no way to unplug it without taking everything out as it sits underneath the AC duct.

All in I'd estimate it was a 1.5 hour job, with 95% of the time being trim removal.

 

For anyone who may come across this post in the future. One more picture to help clarify things. The J46 plug in the diagram below is under the carpet, as shown by the red arrow. You cannot get to it without removing the ductwork from the dash to the back seats shown with green dash where it was removed. The removed piece is outlined in green.

Once the ductwork is removed, you can reach under the carpet, release the connector, and reset it. If you had to remove the ECU itself, it may require cutting the carpet to make more room. As it sits, it's a continuous piece that goes from door to door.

 

Update. This was over a year ago but felt the need to revisit this post. Shortly after posting "Fixed" the light returned. The light comes on and off seemingly randomly. I think I've tracked it down to the passenger seat, likely the occupant detection sensor. It's been a wild goose chase.

 

Could it be a ground?? on and off possibly through the vehicle's vibration maybe shorting out due to a loose ground. I don't think anyone has come across this issue or you would have people chiming in.

 

Checking grounds is on my list. It's weird that its just a B1000 without any other specific codes for whats wrong. It looks like typically it will call out the failing part of the system check. Makes me think the ECU may need replacing.

The other thing I need to do is pull the seats and check all the connectors. I have a sub under the drivers seat, maybe that is putting pressure on one of the connectors down there. Also, I have some Classico covers that may be pulling on wires.

 

Actually I'm realizing now from my previous update picture that this was an issue prior to installing the seat covers, so I can rule that out!

 

Maybe an exposed wire.. Unless someone spilled fluid into it, but the way it's positioned I highly doubt that.

 

Revisited this issue after talking with my mechanic a little. Because there were no codes other than the B1000, he suggested replacing the SRS ECU. He said they require very specific internal resistance checks and it is not unheard of for them to go bad.

I bought a used unit from a local junkyard from the same year/same body style (2007 crew max) for $90 and installed it today.

I started the truck with my fingers crossed. No airbags exploded, the occupant detection lights went through their check sequence, and the airbag light came on and off. So at least I didn't break it. I'll give it a few weeks before calling this solved. The issue was so intermittent it's hard to know if it's fixed or not.

As I suspected in my earlier post, I had to cut the carpet to access the unit. I zip-tied it back together and have no worries that it'll hold just fine. Once the carpet is cut you can access the 3 10mm bolts, 1 from the front, and the other two from the footwell. A good bit of trim needs to be removed but this is an easy DIY job.

 

Three weeks later, and no airbag lights. I think I'm calling this problem fixed. A $90 part and 1 hour of installation [with dozens of hours of research and troubleshooting beforehand].

For anyone else with a B1000, if there are no other SRS codes, I would jump straight to ECU replacement. B1000 seems to point to an INTERNAL problem with the ECU.

I opened up the old ECU, and there were no apparent signs of damage or damaged components on the circuit board. If someone smarter than me wants it to poke around let me know, otherwise it goes in the trash next week.