Tow vehicle isn't charging trailer...weird one...

[Derick]

Ok, this is very strange. Originally, my tow vehicle was a 2006 Toyota Sequoia. I had decided it was a bit anemic for pulling my 23" toy hauler. I have since sold it, and purchased a 3/4 ton suburban 2500.

Unfortunately, starting in 07 Chevy doesnt wire their trucks to be fully tow compatible right out the gate. You have to fish out the wires for the charging circuit and the brake controller circuit in the engine bay, and route them into the fuse box. From there, you have to fish the brake controller wires out from the dash, and you're in business. Not overall terrible, but just like...why?!?

Anyhow, my brake controller was already sort of set up as the PO of the vehicle had a crappy controller installed. I have since removed it and installed my Prodigy P3. Works great. My issue is the charging circuit.

I get 12V at the 2 oclock pole on the 7 pin connector on the truck. Also, I get 12V at the corresponding pole on the trailer side, presumably from the camper battery back feeding it. Everything worked fine on my sequoia...but it wont charge the battery here. Any thoughts on where to start? I'm going to check out the 40 amp fuse under the hood. It may be near failure where it can pass 12V, but no amps/load.

[Derick]

Thanks for all the suggestions.

I took a few steps today and I think we're good again. After work I replaced the fuses for both studs and cleaned their respective contacts. Now I'm getting 14v at the 7pin and 13.5v at idle at the battery connector.

[theoldwizard1]

Derick wrote:

I get 12V at the 2 oclock pole on the 7 pin connector on the truck. Also, I get 12V at the corresponding pole on the trailer side, presumably from the camper battery back feeding it.

One more step !

Turn off all 12V load in the trailer. Disconnect the trailer battery and see if what voltage you are get AT THE BATTERY CONNECTION With the engine running a high idle. I will bet it is less than 13.5V.

Read this on DC-DC battery charging.

[dougrainer]

With the Engine running you should have 13.4 volts or higher on the truck 7 pin connector. IF NOT, then that is your problem. Doug

[wa8yxm]

Since Chevy's tend to run "HOT" electrically (high voltage) it SHOULD be charging. Several suggestions

First is there a fuse between plug and battery on Trailer?

Second. Inspect all wires.. To do this use not a volt meter but a TEST LIGHT You can buy one at any Auto place. (looks like an ice pick with a wire) or you can make one..

Bright light is good. DIM or NO light after the volt meter shows voltage indicates a bad connection or bad wire.
Check both Truck and Trailer YOu should have voltage full time on the trailer on the proper pin.. Just to the side of the index as I recall. On the truck when it is running.

[ndrorder]

For current to flow, electrons have to move, and the voltage on the truck connector has to be greater than the trailer voltage. 12V each does not equal charging.

[beemerphile1]

You need positive and ground both.

[enblethen]

Double check the ground connections.

[racer4]

What year is your Suburban?

Maybe this info on Silverado will help.

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/21726787/gotomsg/21732288.cfm#21732288

https://www.dieselplace.com/forum/76-speciality-forums/81-electrical/70501-12-volt-power-my-trailer....

[Derick]

troubledwaters wrote:
I don't understand, if you got 12V on the truck side, you are charging the battery.

I know. I dont understand either. It doesn't make any sense. For instance, when I towed the camper home with the sequoia from KY, everything was ON as far as 12v goes. Even without the battery. Now, I got nothing, ever. It was hooked up for an hour yesterday and while the battery was dead, it should have given it enough charge to fire up the LED interior lights. Still nothing.

[troubledwaters]

I don't understand, if you got 12V on the truck side, you are charging the battery. I didn't look up what pin should be hot so I presume you got that part covered. As far as charging the battery is concerned, how fast it charges depends on how many amps your alternator is producing and how many amps are not already being used by the vehicle.

[enblethen]

Did you remove the dummy fuse and install a thirty amp fuse?