If that doesn't cure the problem , check the multi wire pin connector that comes outta the steering column , there are two of them side by side right at the dash brace mount for the steering column. Mine had a loose connector in it and I ended up loosing my turn signals intermittently. One time they'd work , then they wouldn't .
Seemed that when my knee bumped into the harness , it would make the connection and work. Had me stumped for a bit till I found it .