7 pin question

BlueTAG

How does one know that their 7 pin connector has a wire in it that is charging the battery on the trailer while on the road? Is there a simple test to perform to determine if my 7 pin indeed does have the 7th wire that charges the battery? TV is Lincoln MKT with factory installed towing package.

Nsummers

Copied from an old post:

@Michigan_Mike said:
If you're unsure of it, hook your tow vehicle to the trailer, plug the trailer in to the receptacle at the rear, use an LED digital 12V DC meter (cigarette style plug), run your vehicle with it plugged in and take voltage reads while turning the battery switch on and off. I have heard people say their wiring was incorrect as some switches have been installed by others after the trailer was built. Additionally, some vehicles come wired with a charge line wired to the battery (there should be a fuse at the battery), but not all vehicles have this dedicated charge line running to the rear of the vehicle, so there are times when people find this out the hard way while traveling and away from home. This is why it's always good idea to verify things on your own with a digital volt meter to ensure your trailer battery is receiving a charge.

Hope this helps!

Sharon_is_SAM

With the 7 pin connected to your TaG, isolate the battery (turn off disconnect switch or remove battery fuse), start your TV, then turn on a light in the TaG. If the light comes on, you have a charge line. Turn off your TV. If the light goes out, you have an isolation relay in the TV. If the light stays on, no isolation relay.

These come in handy.

WilliamA

Keep in mind that plug-in testers are really handy and worth having in the tool kit, but they DO NOT check for amperage. They test only voltage and do not show whether the circuit is solid enough to carry the amperage necessary for electric brakes and charging lines. They tell part of the story....not all of the story. You can get good light readings from the tester and still not be able to charge a battery or run the brakes.

WilliamA

Jiggity

Would it be better to have the TV dealer install everything or the RV dealer?

mgreen2

I would prefer to have the auto dealer wire it since they are more familiar with the vehicle. RV dealers don’t know your vehicle like the auto dealer does.

Sharon_is_SAM

@WilliamA, BlueTag requested a “simple” way to confirm that power is being delivered to the trailer. Agreed that it does not tell the whole story.

BlueTAG

@WilliamA, I did order the adapter from Amazon to test the TV. I do have a voltage tester that plugs into the galley area or inside the T@G. I will test it hooked up in the spring when it comes out of storage. I just want to conform that when it is hooked up to the TV, I need to turn the switch off next to the battery and then test to see if there is power in the 12 volt plug ins. Is that correct?
For now, I want to see if there is 12v power to the 7 pin connector from the TV battery. I figured for 10 bucks I would give the adapter a try.

WilliamA

The adapter tester is a great place to check things quickly. If you find that the circuit tests and passes, but the battery still won't charge or charges slowly, then there is more work to do to trace that. Most often, the culprit for slow charging ends up being a too small ground wire from the trailer to the TV. As with everything, don't fix it if it ain't broke. The quick-tester is a great place to start.

WilliamA

BlueTAG

@WilliamA, I got my 7 pin tester and my TV did test with the 12v light lit on it. Does that mean that the car battery will charge the trailer battery now? Will that keep the refrig on while I travel to keep things cold? Does the switch on the trailer battery have to be on or off for all of the above to work?

mgreen2

Yes, it should charge the battery. Stop and check it while on your trip to make sure. Keep the battery switch ON. I keep mine ON all the time. If you are storing for s long time you might want to turn it off to prevent minor drain on the battery.

The Norcold will work as long as you have a charge on the battery.

JamesDow

If you have the 7 pin power cord for the tow vehicle, the Norcold will have power and work with or without the battery switch on. Be aware that a small Tow Vehicle, like my 4cyl Rav4 without a upgraded alternator will not likely charge up your trailer battery much.

Sharon_is_SAM

Be aware, once you turn the battery switch off, yes you can power the Norcold via the 7 pin but you will also draw down your TV battery.