Confirmed solve for Bike rack sensor nonsense

doubleD

doubleD

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Apr 8, 2025
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The below trailer emulator disables the electronic Nannies, confirmed on my 25 LC.
It is not intended to be left out in the rain and weather or used while driving.
I suspect it get hot given the vents, and it isn’t weather proof.
I’ve got an extension cable on order o relocate the unit somewhere out of the weather (possibly inside the bike rack, we will see) and if it is a confined space a small fan connected to the 12v accessory pins might solve any cooling issues.
No, it’s not worth it for a normal person but I love me a project lol

 
You don’t even hit the tow haul button. You plug it in, start the truck and you get a message saying some systems are disabled. You just clear the message and go.
You can use tow haul if you want the truck to do actual hauling and towing things with the tranny and whatever it does.
 
At that price I'd seal the seems with epoxy and encapsulate the LEDs with some clear silicone. I'd still use an extension so it doesn't get busted off from road debris or ground contact and then ziptie it up under the bumper.

From a trusted brand too, they make great trailer brake controllers.
 
What do you think about temperatures with your solve? I had the same gut reaction but resistors can get really hot…
 
I don't think there is much inside that other than possibly a small circuit board and the LEDs. All the vehicle is looking for to sense the trailer is a connection on the pins (small load from each going back to ground) and the LEDs should take care of that. At most there may be some SMD resistors on it but I wouldn't worry about the heat, there is no ventilation built into it which tells me it shouldn't be an issue and if tucked up behind the bumper it will get plenty of airflow while driving. The LEDs will be the biggest heat source from what I'm seeing and they don't get very hot either.

I have 30 years working on electronics and wouldn't worry about the heat in this case.
 
Bad1975 said:
I don't think there is much inside that other than possibly a small circuit board and the LEDs. All the vehicle is looking for to sense the trailer is a connection on the pins (small load from each going back to ground) and the LEDs should take care of that. At most there may be some SMD resistors on it but I wouldn't worry about the heat, there is no ventilation built into it which tells me it shouldn't be an issue and if tucked up behind the bumper it will get plenty of airflow while driving. The LEDs will be the biggest heat source from what I'm seeing and they don't get very hot either.

I have 30 years working on electronics and wouldn't worry about the heat in this case.
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Ok well yes you are certainly more knowledgeable about electronics than I am. One thing however is that the entire underside of the unit is basically vents. You can see straight thru it to the circuit board. Probably 3-4” long and half an inch wide of ventilation. That is what spooked me on the heat factor.
 
Could always plug it in for a few minutes and check.

Cab you see any components on the board or any through mount solder connections? If not there are either no components or its all SMD (surface mount) components which run considerably cooler than the older through mount stuff.

Could also check resistance with a multimeter from ground pin to each pin, if there are no resistors it will likely be less than 1 Ohm or very low resistance with black on ground and red to each pin, should be very high to infinite with leads reversed.
 
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Bad1975 said:
Could always plug it in for a few minutes and check.

Cab you see any components on the board or any through mount solder connections? If not there are either no components or its all SMD (surface mount) components which run considerably cooler than the older through mount stuff.

Could also check resistance with a multimeter from ground pin to each pin, if there are no resistors it will likely be less than 1 Ohm or very low resistance with black on ground and red to each pin, should be very high to infinite with leads reversed.
Click to expand...
Ok update.
Some pics from the outside and the inside of the unit.
I plugged it into the truck for about ten mins. There was a perceivable warmth the exterior shell but I not even close to what I would call hot. It was about 50 degrees in my garage so that probably contributed.
Any thoughts seeing the internals?
I hit it with a multimeter but most of the pins give me OL despite it being auto ranging and I tried reversing the leads also, same result. The 12v and Brake controller were the only ones to give a reading - 98ohm and 1.6kohm respectively. Perhaps it needs voltage applied?
Given it wasn’t heating up much I think I will drop the spare and look for a dry place to relocate it with the extension plug.
 

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kobyneal said:
Honest question - doesn’t this button take care of all these issues?
Click to expand...
Nope. that stops the autobraking, but the parking sensors still scream at you. You can mute them once they start, but then you're turning crap off and waiting for a scream until you can mute it, or turning off your front sensors in the MID. The idea with this plug is to be able to just plug it in when installing the rack, and unplugging when uninstalling the rack & never thinking about it.
 
doubleD said:
Ok update.
Some pics from the outside and the inside of the unit.
I plugged it into the truck for about ten mins. There was a perceivable warmth the exterior shell but I not even close to what I would call hot. It was about 50 degrees in my garage so that probably contributed.
Any thoughts seeing the internals?
I hit it with a multimeter but most of the pins give me OL despite it being auto ranging and I tried reversing the leads also, same result. The 12v and Brake controller were the only ones to give a reading - 98ohm and 1.6kohm respectively. Perhaps it needs voltage applied?
Given it wasn’t heating up much I think I will drop the spare and look for a dry place to relocate it with the extension plug.
Click to expand...
Wow, after seeing that I would not seal it up, those resistors and transistors will generate allot of heat. I don't think no matter what you do it will last long if left plugged in for extended periods of time. Looks like its been designed exactly for the purpose of testing only and shouldn't be used for prolonged operation.

To have any chance at all of long term use you would need it inside the vehicle in an enclosure with a fan.
 
Bad1975 said:
Wow, after seeing that I would not seal it up, those resistors and transistors will generate allot of heat. I don't think no matter what you do it will last long if left plugged in for extended periods of time. Looks like its been designed exactly for the purpose of testing only and shouldn't be used for prolonged operation.

To have any chance at all of long term use you would need it inside the vehicle in an enclosure with a fan.
Click to expand...
Is it the resistors primarily that are going to create the heat problem and short operating life?
I could easily build a little project box with a fan and just run it off the 7-pin’s 12v accessory power…

I also assume you could upgrade those resistors to some with heat sinks and higher wattage values if I were to lose the OEM plastic case and put the board in a project box with a fan… ya think?
 
Yes the resistors and transistors (circular metal case components) will generate the most heat.

A higher wattage at the same resistance won't generate any less heat, the heat is being produced by how much current its preventing via resistance, the wattage would just allow it to handle higher current without damage.

Project box with fan would probably extend its life as well as heat sinks, I'd probably skip the heat sinks for the resistors unless you can run a thin flat sink under the resistors and use heat sink paste. Transistors would also benefit from heat sinks if you can find the ones that go around the body with fins?

Honestly I'd try just removing the case its in and slapping it in a project box with fan/fans (Inlet and outlet). If you mount it vertical and have the intake fan on bottom and exhaust on top it will have the greatest cooling effect and orient the big resistors to the top as well to aid in natural heat loss with that setup.
 
bigthom said:
I leave my bike rack on, I clear a message and don't have any issues. I don't get this.

I turned off the auto brake and...that was it.
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I do the same but it's a constant reminder (multiple times a day) as I manually clear the message every time I start my truck that Toyota should have thought this through and given us an option.
 
doubleD said:
You don’t even hit the tow haul button. You plug it in, start the truck and you get a message saying some systems are disabled. You just clear the message and go.
You can use tow haul if you want the truck to do actual hauling and towing things with the tranny and whatever it does.
Click to expand...
Does it disable Cruise Control? I was towing a camper a few weeks ago and I think CC was disabled which is not surprising. I'd much rather have to clear a message and have CC available than not clear a message and not have CC available.
 
kobyneal said:
Honest question - doesn’t this button take care of all these issues?
Click to expand...
I turned this off and the rear sensors, but not the cross-traffic alerts and it worked wonderfully for my MTB race that was in total about 6 hours of driving.

Edit: No problematic sounds when backing up, just a pop-up message when I'd start the truck the first time which I'd immediately clear.
 
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