Replace 4wire rotary dimmer light switch

The light switch for the kitchen ceiling lights has failed. The switch has two pairs of wires. Red (in) marked plus paired with a black wire. Red (out) paired with a white wire.
These wires were attached, as follows, to the coach wires:
Red + (in) attached to a yellow wire, black (paired with Red + (in)) attached to a white wire.
Red + (out) attached to a purple wire, white (paired with Red + (out) attached to white wire.
Based on info I found, I ordered a couple of replacement switches from Starcraft Parts.Com. Unfortunately they come with only two wires, red and white.
Has anyone had, and solved, this problem?
Thanks for any help offered.
Bob Hutchins
2008 Cameo F36KS3

Can you put an ohm meter on it and see what the current path is in the ON and Off position. Test every wire to every wire on the switch.
Could you post a pic of it?

Whites should be grounds. Attach the two whites together, and touch the yellow and purple together to make sure you still have lights.

Is the new switch just an on/off rocker? If so, put between the yellow and purple. Direction shouldn’t matter.

If the new switch is a rheostat, then direction might matter. Try it both ways between the yellow and purple. One or both should work.

 New switch installed and working. The solution was, as suggested, quite simple. The two white wires were coach ground wires which we tied together and the colored wires were simply power in and power out of switch. Still not sure why the grounds were routed thru the original switch. Thanks for the help.
Bob Hutchins
2nd National VP, Carriage Travel Club
2008 Cameo F36KS3
2006 Ford F350 Dually

If the switch had a light in it, it would require a ground