rcltrh

On my 2001 ML 430 there is a device kind of in between the battery and the coolant reservoir that has 3 heater hoses connected to it and one of them appears to go into the firewall to the heater core. It is leaking and I need to get a replacement, but I'm not really sure what to even ask or search for. It is mostly all black plastic but has a silver metal housing looking thing on the bottom with an electrical connector, and some valve looking chambers in the plastic housing. Is this some sort of heater water control valve, or could it be - from what I've been reading in old posts on here for all mercedes in general - something called an auxillary water pump? Whatever it is it is leaking coolant a drop or two at a time very slowly but I figure that will only increase as time goes by, just not sure what it is. Any help?