Trailer battery charging
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Logistics Pro
Joined: Sep 2006
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From: Airdrie Alberta
Trailer battery charging
On my dads 08, the trailer battery will not charge while the truck is running and it is plugged in. On my 03 it does charge. He has the trailer package on his truck with the integrated trailer brakes and everything. We are wondering if there is some fuse or something we need to add to get the trailer battery charge system working? Everything else works good, all the lights and everything are fine. Brakes work fine, its just no battery charge with his truck.
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From: Frederick, MD
How did you verify? With the trailer on its own power what is your battery level for the trailer.
With it hooked you to the 08 and the 08 running what is the battery meter reading?
Seems impossible to me for you to have trailers lights and brakes and not charge as everything goes to the power inverter before going back to the battery.
With it hooked you to the 08 and the 08 running what is the battery meter reading?
Seems impossible to me for you to have trailers lights and brakes and not charge as everything goes to the power inverter before going back to the battery.
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Logistics Pro
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From: Airdrie Alberta
We verified with a tester you put in the plug and it lights up everything that is working. The trailer in question is a dump trailer so by lights I just meant, signals and such. We have checked the fuses and traded some around with no luck. Have had the plug out and inspected as well as checking all the wires for breaks or anything like that. Almost might be easier to just run a new wire straight off the truck battery on to the back of the truck and splice in at the harness, although it would be nice not having to do that.
Hotshot
Joined: Nov 2000
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From: Pflugerville, tx
We verified with a tester you put in the plug and it lights up everything that is working. The trailer in question is a dump trailer so by lights I just meant, signals and such. We have checked the fuses and traded some around with no luck. Have had the plug out and inspected as well as checking all the wires for breaks or anything like that. Almost might be easier to just run a new wire straight off the truck battery on to the back of the truck and splice in at the harness, although it would be nice not having to do that.
there is a fuse that controls the relay.. and check the relay too
according to the 08 F250 manual (at http://www.motorcraftservice.com) all located in the engine compartment
33 10A Trailer tow brake controller, Trailer tow battery charge relay coil
44 30A* Trailer battery charge relay
56 Relay Trailer tow battery charge
so, 56 is the relay itself, 44 is the actual power lead fuse controlled BY the relay and fuse 33 controls the relay
Sam
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Logistics Pro
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From: Airdrie Alberta
It says it is not working at the truck end. We have tried switching the relays around as well as the fuses to no avail. likely going to have to just run a new wire or something.
More Turbo
Joined: Aug 2006
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From: midland, Ontario
I don't know, but on my 04 the charge wire had to be hooked up from the harness to the plug. It was not connected from the factory.
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Hotshot
Joined: Nov 2000
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From: Pflugerville, tx
and at one side of the relay, and another when power is on..
you ARE measuring while the key is on, right? on ford trucks there is no power when the key is off..
chevy's etc pass it thru all the time.
Sam
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Logistics Pro
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From: Airdrie Alberta
We tested it all with the test light and everything, always truck running even. Possible there is a break in his charge wire. Was just hoping there might be something we were missing that needed to be plugged in other then running a new wire, which is simple enough.
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Joined: Jan 2008
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From: Washington,KS/Lincoln,NE
Are you checking all the right fuses? The fuse for the 12V + at the trailer plug is a super fuse in the box under the hood on a 2008. I don't remember the number, but it's detailed in your operator's manual. I've had to replace mine several times if I forget and let the truck run while raising/lowering the electro-hydraulic jacks on my RV. In my '08 there was no need to connect wiring. It was done from the factory.
Last edited by Larry NCKS; May 11, 2010 at 09:17 PM. Reason: added info
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