No Lights

2000 Dodge 1 ton with the Diesel engine. The headlights and brakelights work as well as the turn signals but there are no park lights, including the lights on top of the cab. This is Dad's truck and he hasn't tried anything to fix it yet because he is lost.

So, any ideas on where to start troubleshooting (and how)? Any resources that we may be able to use to figure this out? We are both good at working on cars, just that he's never had one this new and electrical isn't my forte. I appreciate any help that you can give me.

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