Solar inverter 'charging' light... not lit

[BigWapiti]

Within the year, we purchased a 2004 Lance 915 used. It's been great. It seemed that the solar panel was charging, but I never did really check anything about it. I just know that when camping (I always dry camp) the batteries would show full charge by end of day. Now, however, it seems things have changed. I'm showing "G" rather than "C" at the end of any given day, and sometimes lower depending on what we do. It got me wondering. I peeked under the sink to find the solar box. There's an LED that has written next to it, 'charging'. I presume this will illuminate when the solar panel is actually charging the batteries?

We're leaving for a 4d trip tomorrow morning - of course, this just now came to my attention.

1. Is that led supposed to be lit when the panel is proving current to charge the battery?

2. is there a way I can test this box? my manual is worthless in this arena.

3. What is the most common thing to go wrong ... something I could check first?

Anything else you might offer would be great - I'm mechanical in nature, but when it comes to electronics, I've never taken an interest (sigh... wish I had).

I've been searching the forum here, but coming up short.

[BigWapiti]

Thanks for the quick reply. I did go through and check connections - it's pretty tight in there, but everything seems solid. I went up on the roof and disconnected and reconnected the plug. Seems tight.

I checked V at the battery: 13.0

I checked V at the Solar regulator:
BATT terminal: 13.0v
ARRAY terminal: 1.50v

Something I don't quite undersand too on the solar regulator -there are four total connections. the two on the left are BATT and ARRAY, shows [--Positive (+)--] above it. The two on the right say the same: BATT and ARRAY, but shows [--Negaive (-)--] above it. The side that shows voltage is the side that says "POSITIVE" .. The other has no V reading. I'm not understanding what is meant by POSITIVE vs NEGATIVE over the two separate terminals for BATT and ARRAY.

I only have one solar panel.

[kerrlakeRoo]

First thing always is to check your connections, especially the grounds.
Next check voltage at the battery, if the unit is charging the voltage should be up above 13.5, if not, back trace through the system to find where the voltage is being lost.