Hello. I am looking for the fuze number for my running lights on my trailer 7 pin for both the bumper and in bed attachment. The blinkers on all my trailers are working as are the break lights. The diagram that I got with the manual doesn't seem to match up to the fuze box. Also I need to know how to open the engine compartment fuze box I don't want to break it. Thanks.

 

. You have a 2015 F 350?????

Trailer Tow parking lamps.

fuse location # 26 (30A)
Relay location # 29..

for my 2012 anyway. under hood fuse box.

 

My 07 E350 has factory tow package and therefore: two full size batteries.
Batteries are expensive and when one of mine went bad, I just swapped it with the secondary battery and then taped/insulated the wiring to prevent sparks.

The van worked perfectly normal until I towed my trailer the first time and I realized the exact same problem you described. Turn signals and brakes lights worked, but no running lights.

Long story short: the 2nd battery has to be hooked up for the running lights to work. So I bought a new battery and now I enjoy (yes, actively enjoy) my properly functioning running lights.

 

After doing some poking through the diagrams and, assuming 1) they are correct and 2) I've interpreted them correctly, it would seem that your auxiliary battery relay wasn't working. If it was, the trailer running light circuits would have been powered off the primary battery which is switched in parallel with the auxiliary battery so that both are charged.

 

Are you saying there's an issue with mine? or are you referring to the OP's issue?

along the same lines: I'd love for my two batteries to be parallel'd so that I could get longer reserve time and better cranking.

 

Yep. That's what your symptoms suggest.

The OP hasn't returned to the forum since posting in order to clear up the ambiguity of what he's working on or with.

Your van's aux battery system wasn't designed for that purpose, it was designed to support a trailer when the van's engine isn't running so that the trailer's power draw won't run down the main battery.

 

I've been thinking about this since you posted it. Any chance you'll share the schematic you saw?

 

Sure. See attachments.

If you need the analysis of how it is supposed to work, I can put something together.

 

Ok it's a little more complicated than I thought. But even the basics don't make sense:
why is Battery 2 positive side not hooked up?
why is there no Battery 1?
what controls coil side of the the relay before Battery 2?

and some more questions I can't remember because I can't view both web pages at once.

Maybe ill I'll check this out on a real computer and get something figured out.

 

You're going to need to either view on a larger screen or, even better, print out the drawings.


Sheet 95-1:
Battery 1 is not shown on theses sheets, these drawings are for the trailer adapter circuit. Battery 1 output is fed into this circuit in two different paths. One is via fuse F12 and is denoted as "HOT IN RUN". The relay is to be energized via the diode when the key is in RUN. The other is fed in via ALWAYS HOT fuse F20 and goes to the COMMON terminal of the relay. When the ignition key is not in the RUN position, circuit 3258 is powered only by battery 2. When the key is in the RUN position, battery 2 is placed in parallel with battery 1 so that that battery 2 can be charged and both batteries supply circuit 3258.

Sheet 95-5:
Circuit 3258 provides for power to be available at the COMMON terminals of the three relays shown via the respective fuses. The relays are energized as follows: Backup lamp relay when the van's backup lights are on, the parking lamp relay when the van's parking lights or headlights are on, and the trailer charge relay is on when the van's ignition switch is in RUN or ACCY position.


Battery 2 is connected to the normally open terminal of the aux battery relay. You'll need a better viewing experience to distinguish the line in the drawing.



.

 

 

The aux battery relay is either defective or isn't getting energized when it should. See previous remarks.

None of those functions are reliant on the aux battery under any circumstance. See previous remarks.

 

your first statement (quoted here) seems to be an explanation/diagnosis of the symptoms.

Your second statement implies that my symptoms arent aren't related to this discussion.

It seems your two statements contradict each other. Right?

 

Wrong. The aux battery has nothing to do with anything other than the three SPECIFIC functions I identified in post #10. That means the trailer turn, brake, and hazards as well as all of the van's lights and accessories are all independent of the operation of the aux battery circuit and all will operate normally without the aux battery's contribution.

 

ok Smarty Pants you were right. I had some free time today and I’ve had it in my mind to prove you wrong for a couple months, so today I dove in. The aux battery had 12.44volts at all times. Key on, key off, engine running. The only thing I couldnt do is plug in my trailer to the factory harness.

so I dug deeper- the relay clicks loudly (engine running) when I remove/reinstall the small wire.
But one of the big wires always matches engine running voltage 14 +/-
The other big wire always matches the aux battery voltage of 12.45. Even when the relay clicks nothing changes.

So I removed the relay and when I shake it it rattles internally. I’m at Advance Auto now to get a noob.

So so now that I know I’m wrong : I want to understand this system.
I’m thinking it’d be cool to have two batteries crank the engine and run all the accessories. If I were to bypass the relay and just connect the cables together.

But im smart enough and careful enough to wonder why Ford wired it in a way that is slightly above my knowledge level.

Heres the thing: everything works- trailer lights, trailer brakes, everything.
If this relay failed then
1. how important could it be?
2.what exactly does it do?
3. Why do my trailer running lights not work when I have the aux battery removed? But the brake lights and turn signals do.