Hoping someone can help me with my 97 xlt, I have the 4.0 ohv. My front driver side running light is not working. Works with turn signal, and hazards, but running light does not work. I’m new to diagnosing electronics and don’t really understand the wiring of these lights enough to easily diagnose the issue. I replaced the bulb with a known good bulb with no luck. Passenger side works without issue. I have a digital multimeter but don’t really know where to start. Thinking it may be a ground issue but if anyone has any ideas let me know.

 

Are these lamps single filament or double?
Are you familiar with your meter? Sometimes just plain corrosion will stop a lamp from functioning.

Remove the passenger's side bulb and test the contacts with the circuit on. That means test for 12v on the center contacts. See if the socket is getting electricity. Make sure the black lead is on a good ground.
How do you know the bulb is good? Did you test it? Is the vehicle new to you? Perhaps a previous owner tried installing an incorrect bulb and forced it in. Twisting hard with an incorrect bulb can damage a socket to where contacts don't line up. You could even be doing this yourself.

You mentioned "a ground issue". It seems the bulb lights with turn signal and hazards so it's got ground there. I don't know which bulbs you have. Sometimes on older vehicles the contacts wear and just don't touch. Are these metal based bulbs or the flatter bladed ones with wire contacts?

 

Thanks for the response,

Ended up being a pretty simple diagnosis. Both harnesses had 12v with the key/running lights on. I switched the working passenger side socket into the drivers side and everything worked, looks like I have a bad socket. Easy fix, $10 part. Thanks for the help. So glad I didn’t have to track back through the harness to find the issue. Already working on that with the 02 sensors and let me tell you that is a pain.