What Does Yellow Warning Light Mean?

Do you mean the glow plug light?

On my '82 and '85 diesels, a blinking glow plug light indicated water in the separator. Of course, its standard function is to indicate when the glow plugs are on. It should go out after a delay, or as soon as you start cranking the engine.

If it comes on when you turn the car on when it is below 40º F it is the glow plug light and it is trying to tell you to leave the ignition on, but don't turn it any further until the light goes out, then turn it the rest of the way to activate the starter. It indicates the glow plugs are being powered up and warming up to help start your engine. It usually takes a few seconds to 30 seconds depending on how old your cars is and how cold it is. I think the max for your engine is about 15 seconds.

Flashing is another problem. It likely looks like some hot coiled wires.

On the older ones, that meant it's time to drain the water out of your water separator.

Does it look like this?

( O )

If so it's the brake pad warning light.