OK, I am new to diesels so therefore new to block heaters. Here is my understanding of how a block heater works: Electricity flows through the wires an into the heater itself where it meets resistence. This resistence generates heat, therefore heating the surround oil. If the information above is correct, then the correct way to diagnose block heaters that are throwing GFI circuits or breakers is to use an ohm meter to check the resistance between both prongs It should read high resistance. If little resistance then the element itself is bad. Next, check each prong against the ground prong. If either read low resistance then there is a short to ground so you should check the wiring. Does that sound right? I have found there are many conflicting stories on how to diagnose this problem.
Are you checking the end of the cord or the actual heater element? I would unscrew the cord from the element and check it separately. Might be a worn spot in the wire. Or depending on the age of the truck the wire could just be worn out, constant heating and cooling will change a wire resistance over time....Let me know what happens. Brian
I visually checked the wire and everything looks ok, but it is hard to see in some places. I will disconnect the wire from the heater sometime this weekend. I checked it out when the wires were dry, so wetness is not the issue.
all wet? First of all , your block plug should be in the cooling jacket in antifreeze not oil. If you have an oilpan heater it would be a silicone rubber blanket adheared to the outside of your oil pan. If you keep popin your gfi, one some gfiz ar 15 amp rated but only ten to twelve amps thru before they pop. Some gfiz are rated for 20 amp and 20 amps thru the circut. Where you are pluging in could be the culprit, what you plug in could be the problum too. block plugs are cheap and apain in the ass, usualy under a manifold in a hard place , so before you replace the cheap plug check your gfi, try another plug not a gfi on a twenty amp breaker. I assume you are just plugging in the block plug by itself and not ganged up with a battery blanket and maybe a 1500 watt cab heater as well. The other guys have good advice , check your cords for shorts, oil,anifrozen saturation. Buy , a new gfi outlet rated for 20 amps , if your block plug is bad and continues to frustrate you, put in a new one, and be happy knowing your rig will start at -20, cause you pluged it , and it works.:stir:
