Hello all:

I have a 2007 F-250 PS Diesel, and have owned it since new with zero issues. Friday, I plugged in my block heater as we were expecting some pretty cold winter weather. When I did, it popped my GFI breaker. I checked for water on the plug, as I had just washed the truck and decided to leave it unplugged for the night. Today, the weather was really bad, so I tried to plug in and my GFI popped again. The plug is dry, and the only thing I can think of is that a wire has come loose or something -- too cold to fiddle with it now. Have any of you seen this issue before?

Thanks,
Dave

 

GFI outlets don't like heaters.
If that is the same outlet you have been using consider yourself lucky. Sometimes you can get away with it if the heater is the only thing plugged into it. Did you add something else to the circuit?

 

Nope -- same circuit I've been using for a year and never had any issues before. If the heaters don't like GFI breakers, I'm in trouble. All my outside and garage outlets are GFI protected.

 

The only other thing would be to try a different extension cord and make sure the plug end is DRY DRY DRY!!. GFI are a PITA.

 

There are three things to consider:
Is the GFI on a circuit that becomes overloaded with the heater. Find out what is on that circuit.
are you using a good extension cord. Does it have a short, is it too long, is it not the right guage, is it not grounded
Finally - the actuall GFI might be bad. Thet go bad a lot. Go buy a good one and replace it. real easy job.

-James

 

Whoaa.a.... Ground Fault Interrupts detect when current that is supposed to run between a "hot" and a "neutral" instead run to ground, which normally occurs when the neutral and ground have shorted/corroded together.

You could, for instance operate a shorted hair dryer in a bathroom just fine, until the day you or your wife just happen to also grab a water pipe and you get a serious shock or worse.

This certainly could be caused by a wet plug end to an extension cord, but it also could be cause by a short in the block heater.

If you're not familiar with the use of an ohmmeter, just take the block heater inside to where there is another GFI outlet and plug it in. If it blows again, throw that SOB away!

 

I removed everything from the circuit and grabbed a heavy-duty (12 gauge) 25' extension cord -- still pops the breaker. It's too crappy out to keep fighting with this tonight. I really don't want to try plugging into a non-GFI outlet until I know if the heater is bad. Is there some way to check the heater for a short? I have a multi-meter.

 

Well it occurs to me that you probably aren't talking about a detachable block/pan heater, but one built in to the engine. Guess it can't be tested in the kitchen....

What you can do though, is take your extension cord into the kitchen and plug a lamp into it, and see if the GFI blows. It might be that you've just driven over the extension cord one time too many and its internally shorted.....


Otherwise, you'll have to get an ohmmeter and check for resistance between the each of the flat prongs, and the round one. Note there will be a reading between the two flat prongs, maybe 5 or ten ohms or whatever, but from the round prong to the others should be infinite.

If it isn't the car chassis will be electrified and you won't want to be touching your car handle and yard lamp post at the same time.....


Of course, these are worst case scenarios. As already mentioned, most likely the plug is just wet....

 

Find the block heater end of the cord that runs through the truck. Unplug it from the block heater. I'm not positive on it's location if it is a 6.0, but it is usually pretty easy to find. Plug it in, if it pops, the heater cord has shorted and needs to be replaced. If it doesn't pop, the heater is bad and needs to be replaced.

 

Grab your multimeter and check the resistance at the plug on the block heater. You should see 12-14 ohm's. If it's higher, then you've found the problem.

99% of the time the problem is the plug itself. Either get a new plug assembly from your dealership, or mod it. On my truck, I bought a Marinco plug from Bass Pro Shops, drilled a hole in the bumper, and mounted it. I just cut the plug off and wired it up to the Marinco plug. Here is a picture as an example. This isn't my truck, but I don't have a picture handy of my own truck showing this on my bumper:

 

You are referring to the AC plug for the block heater on the truck correct?

 

The block heater cord plugs into the block heater that is next to the starter motor. All 6.0L trucks have block heaters but not all are shipped with cords.It is not uncommon for the heater cord to chafe.So at worst just replace the cord best case repair the cord.

 

Thanks for the help guys -- I'll try the various tests recommended tomorrow.

 

Now that is a clean setup! I think I'll do the same on mine -- found one of those plugs on eBay for $10.00.

Thanks,
Dave

 

GFI plugs also do go bad. I have replaced a few that trip when any fairly large load (like a block heater) was put on the circuit.

If you block heater checks out OK with an ohmmeter, replace the GFI outlet.

Using a heavier extension cord should not make a difference. the GFI outlet does not examine load, it only looks for current ground wire instead of the neutral wire.