Anyone know how to test the headrest relay? The symptoms are that my headrest will randomly start going down on their own. I can push the switch up to stop it, but it only cancels it out from full retraction. If I take my hand off the switch the headrest will continue to go down indefinitely until the plastic teeth start clicking. It seems like it is completely random, doesn't matter if I'm driving or not as long as there is power (ie, door open or car on).

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1990 190E 3.0L