its a press and hold button not sure what one off hand.Then it is the tuner number buttons if equiped or the crosshairs if equiped for disk change.I wave been in to Pioneer from 1986 so I can help more with a detailed picture if one of the above is not it

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Truck:1997 Ford F-150 STD. Cab 408ci.Twin turbo
Audio:Eclipse,Digital Designs,Phoenix Gold,American Bass

NEGATIVE.