Have you tried them with the parking lights on? With the park lights(or headlights, too) on, the front side marker lights will flash alternately from the front sigs. This adds a little more resistance to the circuit, and may slow the flash speed down. Without the park/headlights on, the side marker do not flash when turning at all.
Also, a bad/loose/compromised ground could cause a fast flash rate, even with all of the turn sig lights working properly.
At any rate, it do sound like the flasher may prolly need to be replaced.
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Joel Adams
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