<hr style="color:#D1D1E1; background-color:#D1D1E1" size="1">I just bought a 2003 Ford F-350 Superduty 6.0 turbo diesel used from a dealer with 89000 miles on it. I got the truck to pull our new 2014 Salem Hemisphere 40 foot travel trailer. I only got the truck yesterday and today despite plugging in the block heater I couldn't get the truck to start, upon inspection I found that seconds after I plugged the block heater into the outlet in the garage it tripped the GFI swithch in the garage plug. I've tried to reset the GFI and plug the block heater in again but it trips everytime. I have plugged other things into the outlet without any troubles. I don't want to be outside today in this weather any longer then I have to, so here is my question....

Do you think the GFI is the problem, or the cord for the block heater, the block heater itself, or something else??? After buying the travel trailer, and truck funds are kind of low, I rather not have to make a trip to the dealer if I can help it, especially on this my second day of owning the truck. Thanks for all your help in advance, Conrad

 

I think the cords go out on these sometimes... You can see it from underneath on the passenger side. Also, I think you can test the heater with an ohm-meter from the plug. I think you should get about 15 ohms.
Cords are cheap (less than $20) - pull it off and see what kind you need. Others here will know what came on it from Ford, but you never know if someone replaced the block heater and cord.

 

Can you try plugging elsewhere?

I have a Koi pond in front of my home and every time I get any moisture at all it trips the GFI circuit. Probably the easiest test.

 

Since you say you can plug other things in with no problems I would suspect the block heater cord or the block heater itself.

With a volt/ohm meter check the pigtail cord and the heater itself for short to ground and continuity.