Tear not charging from truck electrical?

[Wendell Ann Hanks]

Our 560 model does not show on the battery meter it is charging when the truck's power cord is connected to the trailer. All seven of the connections at the truck's connector show power.
What is a best guess as to why there is no evidence of the battery charging once the electrical is hooked up. To test, I use the meter that connects to the outlet, right side, in the kitchen. I make sure the master switch is "on." When hooked to the truck the trailer's running lights and the stop and turn signals work fine.

No fuses are blown.

What is a procedure that I can use to determine why no charging of the battery.

Many thanks.
Wendell

 

[rotus8]

Sorry to hear you are having problems. Is this a new installation? The reason I ask is a different procedure is used to find something that once worked and broke, or something not set up right.

You say all seven connections show power; this is not correct, one should be ground.

Is your tow vehicle running? Some will not power up the charge line if the engine is not running.

 

[Cary Winch]

Wendell,

Start with what Ted (Rotus8) said first.

Other questions. Is this a factory installed 7 pin or a aftermarket (dealership install would also be aftermarket)?

One of the biggest errors we see in 7 pin wiring is not properly grounding. Using the lighting ground to handle the charge and braking ground. It passes the meter test at the 7 pin because there is a ground connection but not large enough to show any usable charge voltage back to the camper. If it is a vehicle wired to european lighting specs (Asian brands are too) it will have had to have a tail light convertor installed. If the ground wire going to the tail light convertor is what the installer is using for the 7 pin ground it won't charge at all because the convertor will limit the current somewhat. Plus, the charge current could and most likely will damage the tail light convertor.

What size charge wire is coming from the tow vehicle's battery to the 7 pin? Should be 12ga minimum, ideally 10ga.

Cary

 

[Mick'nSarah]

We have had the very same thing happening this year. It worked last year (the first year we had this different tow vehicle).

I was on the road when we noticed it this summer. My batteries would not charge while driving, but I had all of my lights. I did find it strange it kept telling me to check my trailer lights, but when I did, everything was fine. Checked fuses, had the connections checked, made sure it would charge when it was plugged in and ended up having the isolator bypassed thinking it was dodgy. When I got home, Mick was getting ready to go out for a new isolator and decided to check the amount of charge coming out of the truck. It was running about 13.1. The isolator doesn't kick over until the charge hits 13.4 (based on our research). This appears to be out problem.

So I am going to be talking to the folks at the dealership about what might have changed in the last year with work they have done. I had a new battery put in my truck a few months back and I am wondering if something is up there. We have also had some other funny little electrical stuff happening.

Not sure if that helps. Having a husband who is an electrical engineer has been helpful in trouble shooting this. Oh, and our truck had the factory installed 7-pin and we use a converter to attach to our trailer due to the connection needing that so my lights don't flash.

 

[Wendell Ann Hanks]

Thanks to all for their input.
Rotus8: The vehicle is new - a Highlander. You are correct, the ground was included in the test and is not powered. My error. The Highlander/trailer combo was checked with engine running.

Cary: The installation was done at a trailer/motor home repair center. I will return with the trailer in tow and ask them to check the gauge of the ground wire. My guess nothing physically has happened to the trailer wiring to account for this non-operation.
I'll report back my finding.

Sarah: Thanks for the report of your on-going "how-come" investigation. Please report any resolution that may or may not be trailer related.

Wendell

 

[Wendell Ann Hanks]

Re: Tear not charging from truck = not hitched?

OK, here's a new take on why our camper battery was not seen as charging while all brake lights, electric brakes, turn signals, etc., in the trailer were operating.

1) I tested the charging by backing up our new 2014 Toyota Highlander up to the trailer hitch, connected the cable and did NOT hitch the trailer. Vila! All electrical worked, yet, no charging of the battery shown on the push-in meter.

2) While getting ready to leave on a short camping trip last week, I hitched up the trailer and connected the electrical and started the engine. Checking the charging meter meant a surprise.
The push-in meter (kitchen outlet) showed charging.

CONCLUSION: My GUESS is the hitch enables the ground to work that is NOT needed to operate the lights and trailer brakes. In effect the ground wire from the car is only as good as the frame connection to the trailer via the hitch.

Am I on-target? If so, what gives here?
Thanks,
Wendell

 

[Cary Winch]

Re: Tear not charging from truck = not hitched?

Wendell,

We do not connect any ground functions to the hitch so if the tow vehicle is using the hitch for a ground it will not work. Likely not your issue though because the lights and such would also not work.

I suspect your issue may be the one Sarah is talking about. Several of the manufacturers with factory 7 pins are starting to install a voltage regulator on the charge line. Toyota is one we have been running into issue with. If your trailer is equipped with the optional battery isolator it might not be turning on due to the charge voltage on the tow vehicle not being high enough to switch it on. Sarah is correct, the turn on voltage is 13.4. So, if you are reading 13.5v or less at the 7 pin on the tow vehicle you will likely run into an issue if your trailer is equipped with the isolator option. The isolator would need to be bypassed out to make the charge circuit work.

Cary