My rear defrost on light just started blinking/cycling off for 30 sec. on for 10 or 15 WITHOUT touching the defrost switch. I am away from home and my manuals does anyone know which relay controls it..thanks

 

Note from DJ
Open up the Junction Block door in the RH kick panel and look for a 10 Amp fuse #12; pull that fuse and let us know if it stops blinking.

 

Well this morning it was pouring rain and I didn't want to kneel in the mud to get to the fusebox...it was blinking when i first started the truck but after a few minutes it stopped and didnt do it for the next hour.. when i hit the defrost switch the light comes on and if i hit it again the light goes off...normal ops.i didn't run it long enough for it to turn off by itself like usual...don't know if its a basic timer function or based on temp of the back window..will keep an eye on it ....thanks anyway

 

Meaning to get back to this for a while...thought the rear defroster was now working UNTIL...mid October and it got cold and wet. Now that I needed it, the defroster would not work even though the lights on the switch seemed to work normal. . Found a great link thru a post here, just cant remember but a search will find it...tons of good troubleshooting info. None helped, found no volts at the back left power connector..right side ground was good. Ended up pulling up the flex boot at the tailgate hinge point, found a ton of broken wires. Power wire broken, rear window brake light broken, A brown wire that I have no idea what it does, and 3 others were almost broken thru. Took about 2 hours to splice in new wires so there were no repairs in the boot..took another 2 hours to jam all the wires and stuff back thru those tight little boots but now everything works hopefully forever