A factory scan tool or a high end scan tool will show past or history codes that have been flagged. Most aftermarket scan tool will only show current code meaning the warning light has to be on to catch the code before the vehicle's computer will shut it off again.
The codes you gave me have to do with the communication between computers in the vehicle. U2105 is the engine/transmission computer. U2107 is the body computer (interior lighting etc.) And C0889 is the electronic brake computer (abs/traction control) has detected low voltage. If any of these codes are still present then there is an issue but it sounds like there not any more. These codes were most likely cause by the electrical system. Changing the battery and alternator has corrected that.
15.2vts isn't that uncommon because this charging system is control by a computer and the computer will adjust the charging output as needed.
As for the air bag light, have you been able to capture a fault code with your scanner when the light comes on? Do both of these test with the key on engine running ***DO NOT disconnect any connector at this time*** Try wiggling the electrical connectors under the seat connected to the seat belt buckle (if your vehicle is a 2 door let me know because the cobalts and pontiacs have history with the seat belts triggering intermittent air bag warning light). Wiggle the electrical connector at the air bag computer (its under the center console and has a 60 pin connector).
Does your vehicle stall at idle or when driving?
Thursday, March 6th, 2014 AT 5:23 PM