Top marker lights not working

[James and Yvonne Hoak]

I have a 1981 dodge motorhome the none of the upper yellow and red lights don't work I checked bulbs they are are ok any suggestions what it could be

[James and Yvonne Hoak]

Thanks everyone for your replys I will check these out

[david craft]

Ground the light to the corner molding and test the running light bases till you find power and work the string from there. If you have power then establish a ground. If it grounds through the base, they make a #9 aluminum hex screw that is excellent to replace the original screw with...slightly bigger and aluminum for reduced electrolysis issues.

[david craft]

These run ina series ...like christmas lights. If you lost them all, look for a breakdown driver rear corner, tail light or above, or possibly driver front where the string begins.

[Michael Mueller]

Bad grounds 9 out of times it's the ground other one would be corrosion try electric spray cleaner in each socket ,I use the spray
$2 treatment is worth a try
Good luck