i searched, but haven't found much info on this. it seems i have a button problem.

the button for the defrost/window heater hasn't worked since i bought the truck. i tried the MFU diagnostic just now, and couldn't get it to "beep" right, but i was able to get the button to light up, and verified the mirrors and rear glass do heat up. turned off the truck, tried to turn them on again and it still wouldn't work. as far as the MFU goes, all the other functions that it controls are working fine (save for the rear wiper/sprayer, but the wiper arm is broken back there and i'm betting the motor is shot).

i'm doing this MFU test correctly, right? hold switch down, turn key to second position, release button. i tried swapping buttons in the dash binnacle, but they all seem to only work in their designated slot.

 

Hit the switch with some electronics cleaner and then deoxit, got the MFU into diagnostic mode. Rear wiper and wash buttons weren't firing what they should but the MFU sent power to both. Cleaned those and they work now too. For the hell of it, cleaned my cruise control button and that works now too.

Word.