SI points to the SDM needing to be replaced. If you also have a U1000 code I would plan on replacing the SDM. If you do NOT have a U1000 code, it most likely the Sensor Asm-Inflatable Restraint Front End. This is just what I read in SI, I would definitely take it in to your local dealer to have it properly diagnosed. It could need either part or both. The U1088 appears to be an OnStar code, any code that starts with Uxxxx is a communication error code. Typically loss of communication with the effected module or sensor.
Actually 0849, SDM does not control the air bag. From my understanding the SDM is the "black box" for cars. It just records every aspect of the car that it can angular speed, braking speed if any, speed upto 30 seconds before impact and between.
A U1088 loss of communication with SDM doesn't mean much.
It means whatever module you retrieved that from did not recieve a state of health (SOH) message from the SDM for a given period of time.
If the code is history, ignore it.
Don't start tossing parts at it.
U codes pop up from time to time all over the place, rarely do I see a car that doesn't have some. U codes are worthless unless they are current or related to another problem that you might be having.
The SDM is the controller and sensor for the air bag system. It has circuitry that records crash data for retrieval if needed. They used to have all kinds of other stuff but these days it is just an SDM and some other sensors, and on CTS you'll find a PPS system for the passenger seat.
I don't know the time window that the SDM will record, and it is only set to monitor certain parameters. It takes special equipment to retrieve the data and it rarely gets examined these days.
I can assure you it doesn't work like everyone thinks it does or how the news wants you to believe.
A module that sets a current U1000 can be faulty and will usually require replacement but only if the code is CURRENT and causing a problem.
Thanks to everyone for there inputs. All of the information was very helpful. Per the responses I also have a U1000C code and the air bag light on the dash is on all of the time. I pulled the passenger seat and there is nothing under it except for the carpet. I also checked under the carpet and did not find anything. Are there any detailed instructions on the site that will show me how to get at the device under the center console? My CTS is an Automatic if that makes any difference.
Sometimes when fat people sit in my passenger seat, the airbag light comes on. There is a yellow connector under the passenger seat that I disconnect and reconnect, then the light goes away. This should be done with the car off. Anyway, it happens about 3 time/year and I just reseat the connector. Some times I do the drivers side as well.
Getting to the SDM is not an issue, however getting there won't reveal anything.
You need to retrieve the codes to determine the cause of the light.
I have rarely seen an airbag component that was bad that showed a visible sign of being bad.
The SDM is a small silver box with a connector on it, looking at it will tell you nothing.
To remove the console you simply need to remove the shifter trimplate, then the 6 screws holding the console to the floor.
There are 4 in the back accessed by removing the plugs and two in the front that you pull the carpet away from the console to get to.
From there you lift up, and undo the connectors at the front or just prop it up and the SDM is right there at the back.
Be sure to follow safety and handling precautions as outlined in the FSM.
Again, without knowing the codes this is a genuine waste of time.