"Servicenews article - After shutting off the engine, you may hear certain noises coming from the vehicle. Here's the lowdown:
â?¢ Noise from Under Vehicle: This noise is caused by the vacuum pump inside the fuel evaporation leakage check module (ELCM). Depending on conditions, the pump will come on for about 15 minutes about 5 to 10 hours after engine shutoff.
â?¢ Clicking from Under Hood: This noise is caused by the electric brake booster (EBB) system. The system will come on for about 3 minutes every time a front door is opened."