How does the truck know that there is a trailer connected?

With my cab-over camper and no trailer as soon as I go to reverse the back up alarm goes off. I thought I would wire in a marker light to the trailer brake circuit but that didn't do it, maybe not enough resistance? The truck still says no trailer.

Any Ideas as how I can fool the system so that when I load the camper it looks like a trailer to the truck?

 

I'm a little confused. If your signature is the correct picture, it looks like the camper interferes with the bumper sensors, allowing it to activate.
If the alarm is the issue, why not just hit the over ride button to turn off?

 

You are exactly right. And I do turn off the alarm on the steering wheel control. I just thought it would be nice if it was a simple fix when I plugged in the camper that it looked like a trailer and turned of the sensors.

 

I am also interested in this too, I have my truck on order and will be using it for a 91/2 cabover camper and that sound like it would be annoying

Troy

 

OK so I played around a bit. I tested my trailer brake wiring and found 1 ohm resistance between the the blue wire (trailer brakes) and white wire (ground).

Also found 1 ohm resistance between the brown wire (tail lights) and the blue wire, that doesn't make sense I may need to recheck that.

Anyway I added a 1 ohm resister between the blue pin and ground, that didn't do it.

 

Troy, Welcome to FTE. As r2Miller said it's not a real big issue. I just thought it would be a simple task but it appears to be more involved then i thought.

Cheers

 

Thanks, glade it not that big of an issue

Troy

 

I think you were on the right track here. Do you have the Ford OEM brake controller? Sounds like you do. The truck knows there is a trailer connected by sending low current pulses through the trailer brake circuit. When it senses continuity, it knows a trailer with brakes is connected. If you connect a small trailer that does not have brakes, you would notice that the truck does not know a trailer is there.

So one would think that installing a resistor across the trucks brake circuit should make the truck think a trailer is there. But only 1 ohm through trailer brakes does not sound right. Maybe you should recheck that on your trailer and maybe try some other trailers too. Keep in mind that your truck is going to send high current through that resistor when you apply your brakes, so a resistor is going to need to be a big one, or it will just burn out. I also find it odd that you had continuity on the tail light circuit. That doesn't sound right.

Since you are trying this, I assume the '12 trucks automatically turn off the reverse sensors when a trailer is connected. The '05 - '07 trucks don't do that. My sensors still fire when the trailer is connected. I can see where it would be a nice feature if they didn't.

 

Hi Bill, I tried the resistor knowing that it would burn out if used but the truck still never seen it as a trailer. I believe the truck is looking for a reactive load not a resistive load. I may pick up a trailer brake magnet and try that. I have the camper loaded now so it might be a couple weeks before I get back to messen with it.

Cheers!!

 

Using a magnet is one of the recommended ways to test the circuit so I suspect it will also meet your needs.

Steve

 

two magnets. Axles always have pairs.

 

they do indeed, but the manufacturers say one is ample to test the circuit. I don't know if that is true as I never test this way.

Steve