Need some help.

[rmk800ak]

ok so my dad has a 1992 3/4 ton with a 6.2 diesel that he uses for plowing. the problem is the parking lites will not come on but after about a half hour of driving they will come on. we have checked the switch and it is fine i was wondering if there is a relay or silinoid that is sticking thats causing this and also where is it located i have checked chiltons and hayes manuals and can't fine anything or i'm not looking at it correctly any help would be appreciated thanks.

[GM-Tech]

No relay or solenoid. Power for the parking lights comes directly from the headlamp switch. Park light power from the headlight switch provides power for the dash lights... do those work when the parking lights are not working?

[rmk800ak]

no the dash lights don't work either when the parking lites are out.

[Turbine Doc]

This is normally indicative of a poor ground somewhere via a "cold junction" that when circuit warms up from current flow conducts current better.

 

Get anal and check every engine ground wire for corrosion GM & Diesels particularly are known for bad ground loops, as a test direct touch a wire to the frame and back of headlight gnd stud and see if it improves