At just about 21800 miles and 19 months service this morning the brake system warning light came on. This is the yellow brake system warning light, not the red brake warning light or the generally similar looking yellow low tire pressure warning light. No other warning lights are on in the service indicator panel. What troubleshooting can I do myself before taking it to service facility?
Not much you can do without a higher-end scan tool. Regular code reader isn't going to tell you what's going on with manufacturer specific codes.