lights pulsate while heat is on. noticed this...

What kind of shape is your battery in?

Beside batteries.......Converter might be failing.

You need to resize you pic to 640X480 per forum guidelines.
It's way too big.

Fuses #8 & #9 are for the slide out motors 1 & 2

BOTH should be 30A
An auto reset DC circuit breaker are being used......not typical in a DC Dist Panel -------- they don't quite fit properly

#8 is wrong size....12.5A
#9 unsure of its amp rating


Fuse # 3 is for your Fridge AND Furnace.......need to strip the wire insulation back a little bit and reattach wire to fuse terminal....some wire insulation is under terminal screw


As for lights dimming/getting brighter---if that is what you mean by 'pulsating'
That is sign that converter is failing.........DC Voltage not remaining steady when DC Load changes.
Need to check Converter DC Output with battery cable disconnected. DC Output S/B 13.2V Minimum and steady

Also need to check EACH battery cell voltage and specific gravity

your furnace uses 12v even when plugged in ,check your batteries and the water level.

Check fuse #4 Bath Lights. It looks like it is inserted crookedly. Looks like the right side is next to the contacts instead of between them.

One other thing to check is the tightness of all connections in the 12v circuit. I found a bunch of loose terminals when checking mine. Some of my connections terminated in a buss bar inside of an electrical box along the frame close to the battery. Pay close attention to the ground wires as well.

Start with those showing in your photo and work back from there. What you are describing isn't normal.

Also, some other thoughts:

3rd wire from top - the insulation wasn't stripped off enough and there is some of the plastic jacket under the screw. Maybe same thing on a a few other connections but hard to tell from angle of photo.

As a general routine thing, check tightness of all connections at the 12 volt panel. Also, is there enough of the wire under each screw - should extend past each terminal a bit. While you're in there, check connections in the 120 volt section too.

99% of electrical issues are caused by bad grounds! Check frame ground and battery ground connections as they sometimes can be loose and/or corroded. Check battery connections and positive connection at battery going to the converter. If there is a mini circuit breaker in the A-frame, see if the pos battery wire runs through it and if connections are loose or corroded.

Use a voltmeter and see what the voltage does when "pulsating". Does it dip down a lot or a little? Disconnect battery and check voltage for state of charge and also see if the converter voltage is correct. Unlikely the cause, but is the 120 volt line voltage good? Do all lights pulsate or just the ones on one of the circuits? Do they pulsate the entire time the furnace is running? Do the lights also pulsate when extending/retracting the slides?

Is the wiring factory or done by an owner? Curious why 600 volt rated building wire was used. If not original, perhaps there's a bad connection somewhere beyond the panel due to non-factory work? Where is the negative wire for each 12 volt circuit connected - is there another bus bar somewhere? If so, maybe there's a bad connection there? I would have expected the negative connections to be at the bus bar on the right. Actually, the more I look at the pics, it doesn't seem factory original.

Not sure what brand that converter panel is, but maybe it's simply old and tired and needs replacing.

We had some flickering lights and I traced it to an improperly crimped connection at the switch - courtesy poor factory workmanship.