Why does my yellow triangle light on my 1987 635csi flicker on and off?

The yellow triangle light on your 1987 635csi typically indicates a warning or alert related to the vehicle's systems, such as the traction control or a general fault indicator. If it's flickering on and off, it could signify an intermittent issue, such as a malfunctioning sensor or a loose connection. It's advisable to check the owner's manual for specific meanings and consult a mechanic to diagnose and resolve any underlying issues.