97 Ford F250 diesel block heater shorts out when I plug it in

Kill power to the circuit before you use that ohm meter, or it will be popin like that block heater

A block heater is just a simple heating element. There are no fuses b/c you run house voltage (120V) out to it, and those are on breakers, so no need for 12V truck fuses.

Block heaters can range from 500 watts on up to 1500 watts. U know those heaters in Wal Mart that only go up to 1500 watts? That's as much as heaters (including block heaters) are allowed to pull off house current. Remember, use a heavy gauge extension cord, not that 100' long skinny thing. That's not good.

OK, to check the block heater, all you need is a simple voltmeter. Switch it to Ohms (resistance). That's the one with the Omega sign. Put one lead on one flat terminal on the plug of your block heater, and put the other lead on the other flat terminal. Leave the ground (round) terminal alone.

If it reads infinity, or open, then your block heater is bad. It's an open circuit.

If it reads resistance, then it should be good. I don't know what readings for a Powerstroke they should have, b/c often resistance changes with how hot/cold it is outside.

If you plug it in to your house and you hear arcing/sparking, then don't use it until you figure out what's doing that. The block heater is usually on the passenger side, although on Powerstrokes it could be different. However if you follow your plug, you're gonna find where that heater goes. Chances are some idiot has pinched the wire.

If you plan on replacing it, soak it down good with penetrate oil. It's gonna be a bear. And remember to drain your antifreeze down.

Block heaters are great b/c it reduces wear on your glow plugs, plus you get hot heat almost instantly after you start.

Plugging it in any long than two hours before you crank it is a waste of time. It can only get the block so warm, and it does it really quick.