Code SO38 on a Cadillac Eldorado typically indicates a problem with the vehicle's anti-lock brake system (ABS). An easy fix can often involve checking and cleaning the ABS wheel speed sensors and their connections, as dirt or corrosion can lead to faulty readings. Additionally, ensuring that the brake fluid level is adequate and that there are no leaks in the brake system can help resolve the issue. If these steps don't clear the code, further diagnostics may be needed to identify underlying issues.