take the hazard switch on the column, and pull it up and down rapidly about 20 times. Push it back down and then see if they start working.
That reminds me of Tae Quon Do class...they had us rub our hands together vigorously 33 times...then do something with them....
I never thought of this idea...but next time I have a problem like this I will try it first...
Then I will take my Power Probe and see if the cab is grounded to the frame...and then check the turn signal circuit going into the ign. switch and then the actual turn signal switch will get the scrutiny...
If you go to the fuse panel and find the turn signal fuse and check for power and ground it would probably help...
Good luck on it...
Oh, yeah...this is the service truck...
well...the work body was put on and the rear lights were adapted...
I would check in the back just to see how everything looks...