2012 Savana light problem

I have a 2012 GMC Savana 2500 4.8 with light problems.The right side lights all work.On the left side only the running lights work.The left brake,emergency and turn signal do not work.Both left and right backup lifts do work.Have checked all fuses,looked for lose wire and dirty plugs but all are good,even changed the bulb which is the double element type.If it were a computer or relay problem I would think the left would not have any working lights.Any ideas on what could cause this problem?Thanks

Both front and rear lefts inop? then probably just exercise the emergency flasher switch (which is part of the multifunction switch) 150 times---on-off-on-off.....xxxxx 150.

The circuit flows right through those contacts that can become corroded, loose,, etc-- you don't really want to replace that multifunction switch-- they are mega bucks....seen it before- but usually no turn signals/brake lights work.

Thanks for the reply.I have searched for a flasher relay but this van does not have one atleast not like the older autos from back in the day.I took out both front left and rear left bulbs this week to back trace my steps and found nothing.The bulb that is giving me trouble has the two elements inside,one works one does not.The one not working is the ones I mentioned before.So at this point I don't know where to go.I have read and been told to maybe replace the actual turn signal flipper arm,it has the turns,wipers,ect but I don't want to go removing stuff and buying something that is not the problem.But to answer your question yes both left rear/front do not work only the running lights work.I have pushed in the emergency flasher on top of the column and only the right side will flash but you are saying push this switch up down many times and see if that does anything?I will give that a try.I believe if it were a bad fuse or computer type problem nothing would work on the left or both sides.Thanks