Front markers on 1978 C10

[MY1978]

Can someone please tell me if the front maker lights on a 1978 Chevy C10 are supposed to blink when the turn signal is engaged?  Since I am normally driving, I really do not know if they are supposed to blink or not.

Thanks.

[bd]

Yes.  The front marker lamps will flash in unison with the front turn lamps when the park lights are switched OFF and alternately with the front turn lamps when the park lights are switched ON. 

You should develop the practice of periodically walking around the truck to check the function of all of the lamps (i.e., headlamps, running, turn, brake, license, flashers, and backup).

[MY1978]

So I am continuing to have an issue with my front driver's side marker.  Problem is when the headlights are off, both front markers and signal/parking lamps blink as they should when turn signal is engaged.  When I turn the headlights on, the driver's side front marker will not blink (parking/signal under headlamp does blink).  Passenger side works fine as do all the rear lights/turnsignals both driver's and passenger sides.   Thinking it was a bulb problem, I have tried numerous LED bulbs in the side marker socket and it still happens.  I ordered new true LED side markers and yet the drivers side marker still will not blink when the headlights are turned on.  I have contacted the company I bought the headlights from and they are saying I need resistors, but it is only one side that is the problem and I am wondering why - which they are not answering that question.

Any one have any thoughts they would like to pass on.  I am so frustrated.  ONE light that will not blink is the ONLY hold up.     I would post a video but I do not know how to make it small enough to share.

[bd]

It sounds like there is a floating ground in the left front lamp circuit, meaning the ground is less than perfect.  The forward lamp harness ground wires that connect to the radiator support on our trucks typically are shared by multiple lamp circuits.  Ideally, the ground connection points should always measure zero (0 VDC) relative to the battery negative post when the connected circuits are energized and operating.

Try this:  connect a DC voltmeter between the battery negative post and each ground connection point on the radiator support, in turn, as you energize the various lamps that are giving you fits.  If the voltmeter registers greater than zero at any time, that ground connection point is compromised and needs to be disassembled and serviced.

[bd]

I should add, if all the ground points measure >0, service the ground jumper between the battery negative post and the radiator support.

[MY1978]

Okay, so WHY I didn't think about this earlier..........I removed the headlights (which of course required me to dismantle the bezel and trim ring) and swapped them.  I installed the driver's headlight on the passenger side, and vice-versa, and GUESS WHAT!!!!  They worked perfectly and are continuing to work perfectly - W........T.........F........!!!!! .   I am not sure how that made a difference, but it did.  So back in business.

Thanks for everyone that provided comments and suggestions.  What can I say..........I am feeling like quite the dumba**!!!!!!