Trailer charge not working
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Fleet Mechanic
Joined: Mar 2019
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Trailer charge not working
Hello, been a long time. On my 2001 just brought home a new trailer and discovered the charge wire for the battery/accessories in trailer is not working. I have no power at the plug, but all other trailer turn lights/brakes work fine. I traced it back to fuse 115 in the engine bay and I understand that there should be power there all the time and I have no power there at all. What to check?
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There are two small relay boxes next to the fuse box under the hood.
Open the covers to each of these rectangular relay boxes.
If your 2001 Excursion has 4WD, then these two ancillary relay boxes should both be populated with two relays each.
One relay box is for the ESOF 4WD system. The other relay box is for trailer towing.
In the relay box for trailer towing, one of the relays (a Bosch type cubical relay) is for the trailer battery charge wire.
Ford did not install that relay when the 2001 model year vehicle was built. Instead, Ford included the relay in a plastic bag inside the glove box, along with a second relay, a 30 amp fuse, and a trailer brake control wire harness with instructions.
Over the years and owners since, the relay may have never been installed, or it may have once been installed, and then later "borrowed" to deploy elsewhere, to replace a failed relay for a critical vehicle function, if the prior owner did not need the relay for towing,.
If you your Excursion is 2WD, you might only have one ancillary relay box next to the fuse box under the hood.
Open the covers to each of these rectangular relay boxes.
If your 2001 Excursion has 4WD, then these two ancillary relay boxes should both be populated with two relays each.
One relay box is for the ESOF 4WD system. The other relay box is for trailer towing.
In the relay box for trailer towing, one of the relays (a Bosch type cubical relay) is for the trailer battery charge wire.
Ford did not install that relay when the 2001 model year vehicle was built. Instead, Ford included the relay in a plastic bag inside the glove box, along with a second relay, a 30 amp fuse, and a trailer brake control wire harness with instructions.
Over the years and owners since, the relay may have never been installed, or it may have once been installed, and then later "borrowed" to deploy elsewhere, to replace a failed relay for a critical vehicle function, if the prior owner did not need the relay for towing,.
If you your Excursion is 2WD, you might only have one ancillary relay box next to the fuse box under the hood.
Thread Starter
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Fleet Mechanic
Joined: Mar 2019
Posts: 1,293
Likes: 164
Thanks, turns out 115 was hot my test light was not getting a good enough ground. I found the relays and re seated them both and they are now working fine. Must have been just enough corrosion somewhere to keep the relay from activating.
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