For those considering cleaning the contacts on their relays, here is what one looks like disassembled.
This happens to be the same as 2 on our older 1999 MADP that drive the Cummins intake heater grids. This relay located under the bed, above the engine on the passenger side rail had corrosion on the external threads causing it to trigger a yellow fault light on the dash (per code) so it was replaced with a new one. This is the old one I rebuilt and tested for a spare. Guts pull out once nuts are removed and tabs bent back with screwdriver. Once reassembled after cleaning the contacts. A larger pair of channel locks work great to bend opposing metal tabs back in place.
1999 Newmar Mountain Aire MADP 4080, Cummins ISC 8.3L, Allison, Spartan MM IFS, Howard Power Center, Chev Trailblazer LTZ Towed w/ BlueOx rigging, Segway X2.