I've had a sound I hear inside the car that has been increasing in intensity over time. Tracking it down, it seems to be coming from the underhood box the ecu is in. I've read that there is a cooling fan in this thing that pulls air out of the passenger compartment to cool the ecu. Noise is just like a PC with a bad cooling fan. Anyone else had this issue?

Chrysler says the fan comes as part of the box - not available separately. Wanted to see what the options were before I took this thing apart.