7-way trailer connector power anomaly?

[RobNC]

I'm in the process of conversion from flooded to LFP battery conversion. Since the LFP's (with lower state of charge) can draw much more than the trailer connector can provide, I added an inline DC-DC converter/charger (Victron Orion variant) to limit current at 18A. I hooked up everything correctly (then realized the Orion needs input power; it's unlike the solar chargers that can get power from output (batteries). My 4G Tacoma has the factory-installed towing package (with integrated e-brake control). With the engine running, I measured zero volts going to the trailer. Confused? I then tried an experiment with my S.O. holding the brake and putting the truck in drive, WOW now it outputs voltage?! Is this typical? I can see how the Tacoma would disconnect power if the engine is off (to prevent camper from draining truck battery), but even with the engine off, it's not outputting voltage?

I saw some related forum post that may be related but it was too old (not wanting necroposting accusation).

According to Google AI: "If your 4th-generation Toyota Tacoma 7-pin harness only outputs power (like turn signals or brake lights) when the truck is in Drive, the issue is typically a software glitch in the Integrated Trailer Brake Controller or a faulty ground wire in the trailer detection system."
Facebook source for AI is here. Unsure if it's related but it seems mostly conjecture and not based on knowing for sure.

So, what gives? Is there a way to make this 7-pin output voltage on the AUX/BATT pin when the engine is running or is this a firmware bug? I had the 7-pin connector fully seated and the camper lights were even on (makes sense as it was dark enough).

While I'm at it, does anyone speak acronym? What is the 7-pinAUX/BATT fuse? I saw some YT video but none of the acronyms seem like 7-pin AUX/BATT charging. THANKS!!

Sponsored

 

[Sagebrush]

So, what gives? Is there a way to make this 7-pin output voltage on the AUX/BATT pin when the engine is running or is this a firmware bug?
[/QUOTE

I've used the power from my truck to charge the house battery in my camper once, and it worked fine. I was getting 13.6 volts at the camper.

But I'm all stock, so it's not the firmware in the truck.

 

[RobNC]

Thanks for your confirmation. I actually had the wrong wire probed (due to my "helper" moving and replacing the DVM probe wire to the incorrect pin). Despite this, I tested again and it seems the truck does output at 13.6V but then it goes to zero. When in drive, it outputs correctly but then stops after about a minute in Drive but not moving. Putting the car in park then drive again, voltage is there again. Mine is 2025 SR5 with tow package, maybe it's something peculiar with my version?

I was probing between ground and AUX 12V per this diagram.

 

[Sagebrush]

Mine is 2025 SR5 with tow package, maybe it's something peculiar with my version?

Mine is the OR with the tow package.

Now, I haven't checked it with an Ohm meter or played around with it, but when my solar system went down on a three-week camping trip, I had a problem. When I built my camper, I put a switch on the hot line coming from the plug. With the truck running, the voltage at the trailer jumped from 12.6 to 13.6, or something along that line, and my battery had plenty of juice after two hours of towing.

Sponsored