Light Problems

[MY50CHEVY]

I have a 1994 GMC k1500 extended cab with 5.7 tbi. When i hook to a trailer and check lights everthing works good, but when i turn headlights on and try to use turn signals they blink once but then dont continue to blink. If i un-hook trailer they work just fine. Any suggestions as to where to start looking. I think i Will check the trailers wiring first, ive pulled several other trailers and didnt have this problem.

[crankman]

Seems like back in the day we used to have to replace the flasher relay with a heavy duty to handle the blinker load. Might be a place to start on my old truck it was a round thing under the dash with prongs on it that plug in. Sorry thats all i can think of to help. Also nice looking truck you have there.

[MY50CHEVY]

Ok ill check that out, thanks its my 72 c-10 ive got a 454 in it that im rebuilding, spun a bearing raceing a camaro ss, i won though!