Trailer Lights Not Working

[richard5933]

I'd start with some binary testing...

First, can you confirm that your truck has power at the connection point when the engine is running?

Some only supply power when it senses a load, and if this is the case you might need to figure something out with the settings on your DC-to-DC charger to 'trick' the truck into seeing the charger before the charger can detect an incoming charge and turn on. In this case, it might be necessary to do something like reconfigure the DC-to-DC to use something other than an ignition sense wire to turn on - mine is set with a simple toggle switch which I turn on when hooking up the TV.

Next, if you confirm that there is power at the connection point to the trailer, you need to confirm that the settings on the DC-to-DC charger are correct to sense the incoming power.

If you have a Bluetooth connection to the DC-to-DC charger you might be able to monitor all this through the app.

Then just continue down the line. If the DC-to-DC charger is sensing the current and turning on, where does/doesn't the power go from there? Can you read it at the output terminals? At the bus bar?

Do you have a main fuse between the charger and the bus bar which might be blown? Or perhaps between the bus bar and the batteries?

[Wazbro]

Originally Posted by Wyokirk

While this is not directly related to the original thread, it may all be connected. I hitched up to the trailer yesterday (only way to make the lights work) to run some tests on the DC-DC charger. I wanted to see how much power is provided by the pickup and DC-DC charger. I first ran the batteries down to about 80% capacity (three 100 Ah lithium) and then covered the solar panels with some beach towels - yesterday PM was cloudy. With the pickup running and the DC-DC charger on, there was +0.15A at the battery monitor. With the pickup running and the DC-DC charger off, the battery monitor shows +0.18A - must be some light coming through the towels.
I don't believe the DC-DC charger is working - at least not correctly. Is it possible that with the DC-DC charger on, power is feeding back to the pickup?

Some tow vehicles don't send power to the 7-pin until the vehicle has been put in gear and some even getting up to a certain speed first. So making sure there is power there when checking is important. Also some have the voltage drop to much for standard voltage settings on the DC to DC to keep it charging.

[Wyokirk]

Continuing to work the issue. Clearly, there is a grounding issue between the pickup and the trailer - I believe it is related to the DC-DC charger. For a trip last weekend, I created a separate ground wire (temporary) between the pickup and camper with a blade connector for hookup. Worked well.

Pickup went to a Ford dealer yesterday to make sure the seven pin connector was providing the correct power - it was not!!! Hot wire not working so they needed to order a module that will arrive in a few days. They also replaced the seven pin connector. The issue may be the pickup is not providing sufficient power to the DC-DC Charger (isolated) to allow it to function correctly.

When I arrived home from the dealer, the first thing I did was back the pickup close the Airstream to see if the lights would work without the temporary ground wire - they did not. But still worked with the ground wire connected.

More to come when the new module is installed in the pickup.

[Wazbro]

Originally Posted by Wyokirk

Continuing to work the issue. Clearly, there is a grounding issue between the pickup and the trailer - I believe it is related to the DC-DC charger. For a trip last weekend, I created a separate ground wire (temporary) between the pickup and camper with a blade connector for hookup. Worked well.

Pickup went to a Ford dealer yesterday to make sure the seven pin connector was providing the correct power - it was not!!! Hot wire not working so they needed to order a module that will arrive in a few days. They also replaced the seven pin connector. The issue may be the pickup is not providing sufficient power to the DC-DC Charger (isolated) to allow it to function correctly.

When I arrived home from the dealer, the first thing I did was back the pickup close the Airstream to see if the lights would work without the temporary ground wire - they did not. But still worked with the ground wire connected.

More to come when the new module is installed in the pickup.

Isolated IS the problem by isolating the only ground to not go to the lights they can't work, along with the brakes (may sometimes work with grounding through the ball). You need to connect the ground to the trailer as well as the DC to DC.

[Wyokirk]

Have not posted on this for several weeks. First, I had to make sure the pickup was providing power - Ford dealer replace the 7 pin connector. Had power from the pickup. No Lights. Took the trailer back to where the solar/lithium/DC-DC charger was installed (other trailer work as well) - they found no issues. Finally hooked a jumper wire (with alligator clips) from the ground input on the DC-DC charger to the ground buss bar. Lights worked. Talked with the Victron tech rep, and he recommended that the ground from the 7 pin connector go the the ground buss bar and then jump from the ground buss bar to the DC-DC charger input ground. Lights worked on a long weekend trip.

Thanks to all that provided input.