Electrical Issues

What's your voltage availability to the accessories inside the cab? IE what's the voltage at your power windows when you're operating them?

Almost willing to bet you've got a cab ground issue.

 

Not sure. Never looked inside an Argosy before. Key thing is you need to check the voltage with the circuit loaded up (by using the accessory). The fact you have multiple cab accessories that are weak lead me to believe you've either got a power supply issue to the offending accessories or a poor cab ground.

 

I had a 2006 Century. The in Cab accessories went wonky, found a loose ground wire from the cab to the chassis.

 

Clean both positive and negative side power. Clean all battery post terminals, battery negative to chassis (or from starter to chassis), chassis to engine, all bulkhead ground ring terminals, and any other ground you might find. Positive as well, clean battery terminals, battery positive to starter, and battery (or starter) positive to the cab.

 

Don’t forget to check and clean cables to alternated also. Most likely what uncleal13 said, cab to chassis ground.

 

Echoing the others... My money says you have a loose or corroded connection, or a ground strap that is broken or missing. The common thing with all of these items is the cab ground. A quick way to troubleshoot if it is a ground issue: get some jumper cables and ground the cab to the frame (bare metal to bare metal) and see if the power increases to the electrics. If it does, you know where to go.

I'd definitely put some scrutiny on all of the ground connections between the cab, engine, batteries and frame. Don't just look at them; take them apart, clean them up with a wire brush and some brake cleaner before putting them back together.

 

On my 84 Mack a small ground wire on the starter broke and lost all power to cab