TV charging cord not working?

I guess I'll have to do some searching.
Our trip out west is 3 weeks away, so I'd really like to get this figured out.

Some Ford vehicles used to come from the factory with a relay in a bag, in the glove box. It was necessary to open the hood, remove the relay center cover, and install the relay. Look in your owner's manual and see if one slot in that relay box is labeled "trailer charge". Check that relay box and see if there is a relay present in that position.

I guess,before a guy did all that, he could put a meter on the charge pin with the truck running and see if power is present back there.

acritzer wrote:
Not sure how this factors in to the diagnosis. But I definitely have brake control.

Then the installer at least did more than just connect the lights from the 4 pin to the 7. So, that points more toward the fuse/relay issue other have mentioned. Can you look behind the 7 pin to see how many wires are connected to it? For a full install, there should be 6 (the 7th is used for special cases) - Ground, Tail light, R Turn/Brake light, L Turn/Brake light, Brakes, 12V).

Of course, the simple thing is to take it back to U-Haul and tell them the 12V isn't working.

mike-s wrote:

acritzer wrote:
The tech had a gizmo to plug into the 7 pin that indicated whether or not it was delivering a charge.

Then it's vehicle/install specific. Relay/fuse possibly, as others who seem to be familiar with your rig have observed. Or the installer just wired the 4 pin lights to the 7 pin, and didn't do anything for brakes or power.

Not sure how this factors in to the diagnosis. But I definitely have brake control.

acritzer wrote:
The tech had a gizmo to plug into the 7 pin that indicated whether or not it was delivering a charge.

Then it's vehicle/install specific. Relay/fuse possibly, as others who seem to be familiar with your rig have observed. Or the installer just wired the 4 pin lights to the 7 pin, and didn't do anything for brakes or power.

acritzer wrote:

BFL13 wrote:
Fords have an isolator so unless the engine is running, you have no path via Pin 4 between trailer and truck battery. (Chevs don't, so Pin 4 is always live if Stud 1 fuse is in.)

Sounds like they don't have Pin 4 on the isolator.

The engine was running.
The fuses are there. But I don't know about a relay. I would have assumed the charge line came automatically with the 7 pin install.

You can get a 4-pin adapter for a 7-pin, but you can't make a 7-pin from a 4-pin. You have to start from scratch with a 7-pin.

mike-s wrote:

acritzer wrote:
Just picked up my TT from the shop and we discovered that my plug from our Expedition isn't charging the trailer battery.

How did you determine that? Normally, you'll get some charge via the hookup, but not enough that you can expect to fully charge a battery while driving.

The way to tell if it's working is to hook a meter to the battery while your car is off - check the voltage. Then start the car. If it's working the voltage will increase (not necessarily by a lot, but any increase shows it's working).

The tech had a gizmo to plug into the 7 pin that indicated whether or not it was delivering a charge.

acritzer wrote:
Just picked up my TT from the shop and we discovered that my plug from our Expedition isn't charging the trailer battery.

How did you determine that? Normally, you'll get some charge via the hookup, but not enough that you can expect to fully charge a battery while driving.

The way to tell if it's working is to hook a meter to the battery while your car is off - check the voltage. Then start the car. If it's working the voltage will increase (not necessarily by a lot, but any increase shows it's working).

BFL13 wrote:
Fords have an isolator so unless the engine is running, you have no path via Pin 4 between trailer and truck battery. (Chevs don't, so Pin 4 is always live if Stud 1 fuse is in.)

Sounds like they don't have Pin 4 on the isolator.

The engine was running.
The fuses are there. But I don't know about a relay. I would have assumed the charge line came automatically with the 7 pin install.

Fords have an isolator so unless the engine is running, you have no path via Pin 4 between trailer and truck battery. (Chevs don't, so Pin 4 is always live if Stud 1 fuse is in.)

Sounds like they don't have Pin 4 on the isolator.