Installing a Battery Charge Relay Blows 10 Amp Fuse on a 2007 Lincoln Navigator

Question:

I just purchased a travel trailer and had the RV dealer install the brake controller. The tech showed me on my 2007 Lincoln Navigator that when he plugged in the trailer tow connector relay battery charge, location 56 in the power distribution box under the hood, it would blow the 10 amp trailer battery charge coil fuse, location 42 at the passenger compartment fuse panel. Best part, nothing was connected to the truck as far as additional wiring. The relay he was using had a tab on top that I pointed out looked different than all the other relays in the same area, which he stated they used in newer Ford/Lincolns and just cut the tab off. Could the wrong relay cause the fuse to blow? If he was using a generic relay but right config, is there a common cause for this?

asked by: Bruce

Helpful Expert Reply:

Ford would certainly tell you that you must use the specific Ford relay for your 2007 Lincoln Navigator. A generic one that is rated and configured the same as that Ford relay should work just fine. But this one that was installed had to be modified and sounds like there is a good chance that it is not the right type of relay and could be the reverse polarity of the one that is needed. That would cause the fuse to blow. I recommend getting the right relay from a Ford dealer.

You will also want to check to make sure the vehicle side trailer connector is clean and free of corrosion, the wiring is all intact, and there are no exposed copper strands touching metal.

expert reply by: Michael H