Tracking down running light problems

[BS_k5]

Ok so my left running lights, like when the headlights are on, both the front and side ones, will not come on when I turn the lights on. I know its not the lightbulb because the blinkers work when the lights are not on, which tells me it also is not a bad connection at the bulb. Both of them on the right side work fine. Any suggestions?

 

[Fordum]

I'm pretty sure the front ones are dual filament bulbs. Not sure about the side ones.
A dual filament bulb could have the running filament blown and the blinker filament work fine. So, either grab a new bulb, or swap it with the other side.
If the blinkers only work with the headlights off, then most likely a bad ground.
If its not the bulb, post back with more info. Make and model of truck, etc, and we will try to take it from there.

J.

 

[BS_k5]

Correct it is a dual filament bulb. Its an 84 K5 custom deluxe. I kind of figured it wasnt a bad ground because there is what appears to be a ground wire attached to both the left and right lights that goes into the dash.

 

[BS_k5]

Oh and I pulled the bulb out to check the filaments and neither were broken so does that mean I should rule out the bulb?

 

[Fordum]

Nope, odds are its good, but never go by looks. Easiest way is to just swap in a known good one. The one on the other side is the closest.

As for the ground, just because the wire is there, does not mean it has a good connection. Also, the socket can have the ground go bad inside.
Swap the bulb first, and then we can check more exotic things.