My Jetta is a TDI. Normally, when then engine is turned off, there is a small electric motor or pump that runs for a few seconds. Yesterday, this pump got very loud. It is making a plastic on plastic, or plastic on????? rubbing "ticking" sound. If I had to guess I say something got in there (either broken piece of pump or external). What is that pump/motor that runs after the engine is stopped? Where is it located?