chimmike

It's getting the same type of signal from any trailer, how is it to discern which is which? There's no control module in a trailer that can 'talk' to the truck. Let's think about how it would be able to recognize the same type of electrical signal from all trailers and discern which is which....

Sweetlou

Right. I think instead of Calling it trailer recognition it’s better to think about it as a trailer profile.

brwarrior

I have three trailers in my truck setup.

1. 5x10 3000lb GVWR utility. Single Axle. No brakes.
2. Big popup toy hauler trailer. Double axle with brakes on both axles. 6200lb GVWR or so.
3. An enclosed cargo trailer that my ham radio club owns. Around 7000lb GVWR, double axle but brakes on only one.

I have not deep dived into the wiring, but I always assumed (be careful with that or you'll only get to keep the first three letters) that the 4 pin was just tied to the same wiring as the 7 pin. How can it detect which one is being plugged into? Now, it is smart enough to detect when the brake/turn signals do not work correctly. Say when the 7-pin plug comes partially unhooked because Ford's decision to mount the damn thing upside down.

It's a big enough pucker factor when you get a "disconnect" warning and you're towing on a flat highway. I'd have some dirty shorts if that happened in the mountains and it reconnected to my utility trailer when I was actually towing the pup.

Steve83

You don't seem to understand wiring or electronics. There's no way for the system to DISTINGUISH one trailer from another. It relies entirely on human input.

kbroderick

The system can tell whether or not it has a load on a given circuit (for at least some of them); try wiring up a utility trailer to a seven-pin connector and leaving the brake wires disconnected. The truck will let you know about it.

Given that a four-pin hookup doesn't have three of the circuits a seven-pin circuit does, it seems like the truck should be able to guess between trailers if the system stored a little more data (or just guess based on presence/lack of electric brakes, since the system does store that info on setup). If there are multiple trailers that match what it knows, it could prompt the user to choose on connection, but that seems potentially obnoxious, especially if you're frequently hooking and unhooking trailers.

Steve83

What it's actually detecting is that there IS resistance to ground (continuity) - not the load (current). But it's not measuring HOW MUCH resistance, or trying to guess WHICH trailer is connected. Only if it's a trailer WITH that particular circuit, or one NOT wired that way.Are you saying you think the truck can tell what shape connector was used to connect a trailer? It can't. But if you tell it that you've connected a trailer with brakes (human input) and it CAN'T detect continuity on the brake circuit, it will let you know that the trailer brakes aren't going to work. If you use a 7-pin connector on a 4-wire trailer, and you tell the truck it's a non-brake trailer, it won't let you know about anything.

Flamingtaco

Tell that to my employer, as they have paid me for over 20 years to be an EE.

I think it's you that haven't thoroughly read my posts, in which I very clearly indicated the system has the ability to tell the difference between a braked and non-braked trailer, as my truck so very clearly does. I don't know if it monitors the 7-pin separate from the 4-pin, or if it simply detects the variable load between trailers, but whatever the system is doing, it's sophisticated enough that it probably can detect different trailers of the same type just based upon the load on each line. I've received warning messages for having a SINGLE clearance marker go out, and for having a single brake side go out. The system is actively monitoring loads, not just checking that a load exists. If two similar trailers have different current demands, the system could easily note the average current, set a tolerance, and use that to differentiate trailers. Whether or not it does that, I do not know, but it does pick out my 7-pin from my 4-pin.

kbroderick

I was thinking it could actually measure resistance, not just continuity or lack thereof, but I forget why I thought that (I may have been thinking about vehicles that are sensitive to LED vs incandescent bulbs because of the different resistances).

I forget what the exact message I got was, but I know that I got an error message with a brakeless sled trailer wired in a seven-way plug (with four open circuits). I don't recall having set up the trailer beforehand, so the truck may have just been defaulting to electric brakes when not being told otherwise.

Regardless, even if it can only detect continuity or lack thereof, it could be able to figure out if it's got more than three circuits with continuity and thus know when the seven-pin connector is in use.

I'd file this under nice-to-have, along with "allow me to program trailer to default truck into tow/haul mode when attached." I wouldn't have wanted my sled trailer to do that, but when I had the enclosed cargo trailer hooked up, there were a few times where I got gas and forgot to put it back into T/H until I was headed uphill and the truck was struggling because I'd forgotten to switch drive modes.

acdii

You guys do know that it uses the trailer lights to detect if a trailer is hooked up or not, not the type of connection used. The 4 and 7 pin connections are tapped at the parking and brake lights, so doesn't matter which one is plugged in for lights, they are one and the same. Go to the trailer screen, there is a light indicator that tells you if a light is out or not. It measures the resistance of the lighting circuit.

Steve83

What have you been engineering for 20 years that's so different that you can't figure out how trailer lights & brakes work? As has been mentioned several times in this thread already (if you can't tell by looking at the wiring diagrams): the truck can't & doesn't differentiate between the 4-pin & 7-pin lighting circuits. So the only way for it to distinguish a trailer with brakes from one without is by the existence of the brake circuit (by continuity, or by a drop in voltage on the brake circuit when it's connected to those low-resistance electromagnets in the trailer hubs). But their resistance is SO LOW, and so dependent on the cleanliness of the 7-pin's terminals, that trying to guess which braked trailer you've connected based on that resistance or voltage would be a waste of time. If the trailer wasn't connected for a few years, or if its connector was exposed to salty air (like a weekend at the beach) or harsh chemicals (like driving within 40 miles of a volcano that has erupted in the past 50 years, or a harsh car wash detergent), or even bad weather (like a hurricane carrying muddy, salty water), its resistance would be significantly different. Even connecting a crusty 7-pin for a while would alter the resistance of the truck's terminals enough to throw off the readings next time the clean one was connected.

How would YOU engineer around all that? When you figure it out, sell your design to Ford or any other truck or trailer manufacturer. Right now, Ford's system relies on a human to tell it which trailer is connected, and how that trailer is wired.If you're talking about older Fords (like the ~'97~11 CrownVic/MGM/LTC); that LCM uses voltage divider circuits to monitor the lights. If a bulb goes out (or if a high-resistance LED is installed), the output voltage goes high, triggering the fault detection. I'm not sure how other brands work.Is it actually measuring resistance? Or is it using a voltage divider circuit, and measuring voltage? I haven't read the details about these newer vehicles.