Rollover Sensor Replacement Help

Hey everyone! I have went through a couple days worth of Google searches and cant find the answer. I just picked up a 2008 H3 Alpha with a bad rollover sensor. I took it to my local mechanic who took a pass on replacing the sensor and just got a call from the GMC dealer that has had it (for a 3 day diagnostic). Long story longer it is "just the rollover sensor" that needs to be replaced...for $1200.

Has anyone replaced their rollover sensors? I know some of you have had a premature airbag go off due to rollover sensors before. I can not find any walkthroughs or really any firsthand accounts about having to change it.

Second I see a bunch of them available (rollover sensors) but they are listed as 2010 - is there any easy way to see if the 2010 is compatible with a 2008 or do I need to get a 2008 specifically from GM (UGH).

Anyways thanks for any potential help or leads.

The sensor is in the center console, just aft of the shifter. Taking the center console out is a pain, because you have the pull the seats, or at least unbolt them and slide the console out from underneath the rear seat brackets.

Once you're in there, the service manual just says to unbolt and replace the sensor. 3 nuts, torqued to 89 lb-in. Disconnect the battery before starting any of this.

Did they give you any diagnostic codes? It looks like a faulty SDM (airbag module) can also be the root cause.

Take this with a grain of salt. According to what I can find online, 25809367 and 25973140 are the 06-09 parts. 20842671 is the 2010 part.

93355990 and 94729712 are the 09 H3T parts. It looks like the 2010 part fits both models, but I can't be certain.

Good luck.

Have you double-checked to make sure it's not a corroded connector? If the carpet got soaked (happens on these H3's)..

If it turns out to be the airbag sensor, or if you need some tech support, I sent my airbag sensor and seatbelts to the guys below and they had it back to me quickly. They do more than airbags, might do roll-over sensor too (??). It was a good service:
https://blogs.myairbags.com/airbag-module-reset-how-to-turn-off-an-srs-airbag-warning-light/

I have also used myairbags with success


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I saw this while I was trolling eBay today. Looks like a different 06-09 part number.

https://www.ebay.com/itm/Airbag-Rol...dule-15837307-OEM-Hummer-H3-2006/303699640464

Ill reach out to myairbags and see if they can assist. I have the trouble codes but need to find the sheet they gave me (my wife put it somewhere).

I saw that Jeff - oddly its labelled as a 06 but the sensor i think was 06-08 (or 09) and the part number doesnt look like it goes. the physical part though looks the same as the OEM one and also the same as the 10 which is why I wasnt sure if they were the same just packaged differently. Cheeky car manufacturers.

GM seems to have certain part numbers that were only only sent to the factory when the car was built. They're different from service replacement part numbers. It's a giant pain the ass to chase down what fits which models and trim levels.

Ok, I think I know what you're askig (was slightly confused initially). I was thinking you were referring to the Lateratal Longitudinal Sensor under the driver's seat. (my bad). Ok. That module under the carpet below the rear of the center colsole is the vehicle rollover sensor AND the airbag module. Anytime the airbags go off, or it rolls over, it collects batch vehicle data from the vehicle (speed, braking, steering, etc) from some seconds before a crash ...which can be read by police (or insurance companies??) at the time of the incident. After that occurance, or an airbag deployment, the module needs to be replaced. It's not just GM, it's a federal law. After the crash/incidence/deployment the idea is that vehicle data will be permenantly stored. You can still drive the vehicle, but the airbag light will stay on and the airbag system won't (or might not) deploy. The vehicle needs to be taken to a dealership for the entire airbag system to be scanned and checked over and the module needs to be replaced with a new one and "paired" (programmed with the new vin) to the BCM by the dealership (or using a dealer scan tool). That's the theory.

I wrote all that for others following this thread who might not know that (It sounds like you're up on this already). Another approach to taking the vehicle to the dealership is to install and reprogram (Pair) a USED module to your car OR .......a few companies like Myairbags.com, have authorization to reprogram modules for, say, body shops, etc, and they can refurbish the EXISTING module which keeps the original VIN and pairing. What I found was it was cheaper to have them reprogram my module than get a used one reprogrammed, in my case.

What they do is drill a 1" hole in your existing aluminum airbag/rollover module case that you send them. The hole is over the main chip. Then they stick some probes in it and dump new programming into the chip (with your VIN) and vehicle information you send them. Then they spray some expanding foam which cover's the hole. They know what the programming should be by the module's part number. I personally didn't like the foam idea, so I epoxied (JB Weld) a piece of round aluminum over the hole they drilled.

Read the ENTIRE General Description in pages 324 and beyond in this link if you haven't already. It tells you how the entire system works:
https://schwarttzy.com/wp-content/uploads/2013/01/Hummer-H3-Airbags-1-4-1.pdf


The Schwartky manuals seem like they're scanned in 'reverse'. The general descriptions are always first in GM manuals. Oh well. Start from the back and work forward. LOL

Thank you for the detailed breakdown Jeepwalker. So if I understand even if I replace the rollover sensor it would still need to be paired with the system through the dealer. Still doesnt quite explain the insane labor cost but the service guy said that it is just a "book price" not based on actual labor times or anything. Ill reach out the myairbag guys and see if they can work something out - I just want the lights cleared off the dash for my own piece of mind. Im curious if I can find someone local to do the pairing for me - just to get it over with faster. This is now my daily driver on top of my (hopefully soon to be) overlanding rig.

How do you know your sensor is 'bad'? Are you sure the airbags didn't deploy at some point? I would pull off the B-pillar plastic and ohm out the seatbelt tensioners. I don't know if a 'chinese' TechII clone scanner can re-program a 'used' (different) airbag sensor, or if there's something different with the dealer scanners (access to porgramming). Maybe one of the other guys here can comment on it. Usually the airbag sensor is dealer only. Yeah, call myairbags.com, and see if they can dump newer programming into an earlier year module. I'm sure they can give you some direction. Perhaps you could send them your module and see what happens. Worst case maybe they have another one and can program it and put your sticker on it. (??). Let us know how it turns out.

I will keep you updated - I have to assume others have had this issue before and hopefully when it is sorted it may save someone else some time, hassle, and/or money. The dealer inspection states:

The inspection found the SIR system has 3 codes stored, B3855 and B3856 Nroll overs sensor discard codes inspect and scan for codes. Recommend replacement of the roll over sensor and reset the STM and clear the codes.

The rollover sensor and SDM (sensing and diagnostic module, AKA airbag module) are two separate parts. It's even on page 11 of the PDF posted above. They're parts 5 and 6, respectively.

The sensor replacement is also in that PDF. Page 127. Unscrew the old one and install the new one. There's no 'marriage' procedure. You don't need a scantool for it.

The yaw sensor under the seat is for the stability control system.

Quick update - I just talked to myairbags and they told me since its the rollover sensor they cant help - nor could they point me to someone that could help. I may order that replacement module thats on ebay and see how the chips fall. I just dont want a accidental deployment because something in the system doesnt jive haha.

I can guarantee the H3 hasn't been in an accident since I owned it (6yrs). The sensor just came on within the past year, my local lube shop pulled the code showing the rollover sensor. That Ebay listing is a steal since everything I saw online was $250 - $300. I'd bet if you replace it you'll be good.

Glad to see H3 Sr live on in H4O!!! Family nickname for 08 is Sr and the new 10 is Jr.

Hey man! yeah this community is great - lots of knowledge floating around and people seem super welcoming! So far she is running like a top, just getting used to the creeks of a new car but overall I have 0 complaints.

I saw the listing on ebay for the 06 sensor and the ONLY reason I have not pulled the trigger on it is I have no idea why the car it came from was salvaged and I would hate to pop it in and have the sensor blow the airbags because of a crash or something on another vehicle. I hope to get it all tied up next week though - and will probably order the OEM one and just install it...the procedure seems pretty simple but Im about as novice a tinkerer as they come. Go slow, follow the book is about all I can hope for (maybe Ill tape it and put up a video for others if they have this issue)

Chances that would happen are really low, but....

Something to consider: if you plan to hang on to your H3 for a long time, might be a worthwhile investment to consider getting a 'good' scan tool so you can see these things and know what's going on in advance. For the price of the OEM part (vs Used), and a trip to the dealer, you could put that money towards a GM knock-off Tech II scanner (~$350 or less). Then unhook the airbags and turn it on. You can see if a used module sends out a fault (or any module/relay/solenoid/sensor/etc doing something not anticipated). Just one saved trip to the dealer could pay for it. I have access to a Snap-On scanner that has a lot of capabilities and has saved my butt many times. Not as comprehensive as the GM Tech II, but not far from it in terms of capabilities, bi-directional controls ...and works cross platform. Eventually most owners get fatigued from dealer pricing or not having the ability to troubleshoot or understand electrical issues (and eventually sell their vehicle out of frustration of being bled money), or some get tooled up. Anyway, just a thought -- glad you have a plan for the sensor. Buying a new sensor/part never hurts either.

I had planned on getting some flavor of scanner -its been recommended across the board it seems and I plan to keep this thing a while...ideallly I will learn how to do stuff on my own as well to save the prices. The only reason I went to the dealer was I am a little queasy about messing with the airbags and was not expecting the 800 dollars in labor they quoted me. Im very much a youtube/google competent repair guy - by that I mean if I can find a thorough tutorial on something, I can get it done. Regardless Ill look for a Tech II scanner and see if I cant manage to find something that will work and save myself some time and frustration. Im going to order that module now as well and just fingers crossed.

You might consider going to the H3 manual and read through the section on airbags if you haven't already. One of the best parts of any GM manual (for any section/topic) is the Description section which explains how things work in concept and practice. Once you understand how things are supposed to work, and why, it really helps clarify matters and makes it easier to troubleshoot & repair. For a guy learning his vehicle and how to repair, it's a valuable resource.

Look through the forums and ask a bunch of questions before you buy the Tech II (or other scanner). So you get the best one that works for you.

Great to hear! This is definitely the place to be!’