I am new to the forum, looking for some help tracking down a problem on my mom's 2005 4WD Sierra. I have searched around here a bit, and haven't been able to find a thread dealing with this problem. My mom mentioned an issues with the ABS light, so I took it out for a drive, and had the ABS and Check Engine light flash once, with a corresponding *Ding*. Both lights went off immediately, and there is no persistent check engine light. Since I have only seen it once, I don't know if there is any pattern as to when it happens, but for me it happened while I was driving at about 30 MPH.

I don't know what this is likely to be an indication of, but with no check engine light, I am assuming there is no code to be pulled. Thanks for any help.