Clogged Cat, Slip Control Warnings, stealership ranting

[Steve85]

I don't know about GM stuff, but when the engine light comes on on a toyota, it almost always also sets the VSC light. Why? For most codes, I don't have a clue. But it does.

My guess would be that throttle (engine power/braking) is used as part of the overall VSC system. When there is problem with the power delivery system, it handicaps the VSC, default is to turn VSC off and warn the driver of impending certain doom.