2005 Silverado 3500 Service Air Bag

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Mar 9, 2019
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I keep getting a service air bag light only when it is cold out. I've replaced the front air bag sensor (the 3500's do not have side sensors that I'm aware of), and cleaned the ground by the front drive side frame. What gets me is this comes on intermittently, but if it does it's less than 40*F. It really likes to do it when it's single digits in the winter. Sometimes it will go out while driving, other times it flashes on and off every 10 seconds, and others it stays on the whole drive. Once in a while when cold it won't come on at all. I have never had it come on when it's more than 50*F outside. This intermittent behavior makes it really hard to tell if anything I do either fixes it, or being able to track it down.

Any suggestions or starting places?
 
I have an 06 1500, but there were two sensors. It said service airbag so I replaced one. It didn't fix it. Replaced the other, fixed. Maybe you have two up front?
 
The system is more than just sensors... there's also the clockspring, which can be a wear item.

There will definitely be more than one sensor-- the system has redundancy.
 
BOTH front sensors under the radiator are the most common issue on those generation trucks.

There will be a history code stored. Try to have omit read
 
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Not sure on the 3500 but the 2500 trucks I have worked on from that era also had one under the drivers seat.
 
Forgot to mention I did pull the codes, but all of them were unknown to the scanner and internet search hasn't helped much.

C0026
C2575
U1301

If anyone has references to where the two airbag sensors in the front are that'd be helpful. I've only ever seen one and found references to there being one. The 3500's are setup different than a lot of the smaller trucks.

I'll take a look under the seat, but I don't think I remember seeing one when I pulled the seat to replace the heating pads.
 
What module were those pulled from? You need to scan the RCM. Air bag codes are B series codes. C codes are chassis codes.
 
It was all of the modules the scanner could do, one of those rental types at the auto store. There were no B codes stored (or it didn't read them), just the chassis and network codes.
 
Most popular airbag issue with these year range GM trucks including SUV models. There are 2 sensors in front on the rad support. You can tell them by the YELLOW connector. Yellow is used for all airbag connections. I always replace both at once. Did about 6 or 7 this year alone. Runs about $100 a sensor depending where you buy. I once got 2 used for $150. Verify your codes 1st with a proper scan tool first.
 
I'm not saying anyone is wrong about there being two sensors, but I would really love for someone to point them out to a blind old me. I only see one sensor (that I replaced last year due to this same issue and the new sensor didn't fix it), which lives in the center of the bottom of the radiator support. There is no left or right sensor, and I cannot find any harnesses with yellow connectors outside of this single sensor.

I have told almost everyone that 3500's are different than 1500/2500's, and I keep hearing there's two sensors on all trucks. Please tell me exactly where they are, because all I see is the one in the picture below (if the picture uploader worked?).

20200512_161324 - Copy.jpg
 
Got a scanner that could read airbag codes. B0035 - Auxiliary Discriminating Sensor Closed or Shorted to Ground. Symptom of this is setting the airbag light, as I've been seeing.

Any clues where to go from here?
 
I looked up your truck in the Chilton Library. It shows that it could have come with either one or two front sensors...apparently yours has one. It also shows a sensor in the passenger door, near the bottom rear.
 
I checked the inside of both passenger doors and could not find any sensors.

I also cleaned the two ground points on the driver side frame, tightened the front sensor pins, looked for any rub through on the harness, pulled the fuse block and checked the wires, pulled the seat and checked the SIR module connector. I can't find any place this would be shorting to ground, unless the sensor itself is bad. I really don't want to buy another $100 sensor just to have it not be it.
 
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