Winnebago camper versions of the Eurovan include an LP Gas Detector, which issues an alarm when gas is detected. This device draws power constantly from the coach battery when it is enabled. This can cause the coach battery to discharge. Some owners disable the alarm by removing the fuse. The operator's manual recommends other ways to avoid draining the battery. Once removed, the fuse and cap can be easily lost.
To locate the LP Gas Detector itself, refer to your Operator's Manual. These Operator's Manuals are available in pdf form on Winnebago's web site if you didn't get a paper manual with your vehicle. As an example, the 1999 manual is located here:
The diagram on page 0-4 (item 18) locates the LP Gas Detector. There is further discussion on page 1-4.