Do you have enough resistance to trip your blinker relay? If you don't, it'll do what you're describing. If you do have enough resistance, it's most likely a ground issue.
“The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed.” ― Robert M. Pirsig, Zen And The Art Of Motorcycle Maintenance: An Inquiry Into Values