Trailer Stability Assist

[rocket rod]

I have an MY16 D4 and tow a camper trailer and it's only 800kg unladen. When purchased I asked the dealer if LR had solved the trailer LED issues and he said yes. I left it at that. The trailer has LED lights and everything works correctly, no pulsing of lights etc. My question is how do I know TSA is working. There is no trailer icon on the dash when indicating and I know TSA does not require electrical connection. My trailer only has the plunger style cable brakes so I'm guessing TSA only works with the car's brakes & traction control. Perhaps the whole system is working but I can't tell. The trailer does not sway, so maybe it is? When should the trailer icon show on the screen? The trailer uses the black plug.

[Chops]

Interesting dilemma.
So, I was towing my camper (Forward Fold) and ran off the bitumen at a rather rough spot. Just pulled the car quietly back into the centre of my lane. I noted at the time how effortlessly it all happened,, just recovered from all that, and alas,, I managed to do the exact thing again.

So, I do believe it all works, and works well. Had I been in the Defender, the rough edge would have been noted very easily and I’d have felt it yanking at the wheel to pull me right off the bitumen.
No bells, whistles or lights came on telling me anything had happened though.

[Ferret]

My trailer only has the plunger style cable brakes so I'm guessing TSA only works with the car's brakes & traction control.

Correct, it's similar to DSC.

When should the trailer icon show on the screen?

When the vehicle has detected a trailer has been hitched. If you get no trailer icon you still have TSA but you don't get the other adaptations like reverse sensors disabled, gear box shift points changed + whatever else is involved.

To get the vehicle to detect a trailer has been hitched you need to provide sufficient electrical resistance in the trailer's turn indicator circuits - ie fit load resistors in parallel to the indicator lights. Once this is done you will get the trailer icon on the dash.

[cjc_td5]

I have an MY16 D4 and tow a camper trailer and it's only 800kg unladen. When purchased I asked the dealer if LR had solved the trailer LED issues and he said yes. I left it at that. The trailer has LED lights and everything works correctly, no pulsing of lights etc. My question is how do I know TSA is working. There is no trailer icon on the dash when indicating and I know TSA does not require electrical connection. My trailer only has the plunger style cable brakes so I'm guessing TSA only works with the car's brakes & traction control. Perhaps the whole system is working but I can't tell. The trailer does not sway, so maybe it is? When should the trailer icon show on the screen? The trailer uses the black plug.

Yes the D4 only sends a pulse to detect the trailer on startup and when the driver's door is opened (IIRC), not continually as the earlier D3 did. Therefore the pulsing issue has gone. If you have LED trailer lights the D4 may not detect any load though so trailer functions will not activate. The easiest way to fix this is to install a load resister into one of the indicator circuits on the trailer.

The easiest way to see if the trailer functions have been activated is the stick it in reverse. If the reversing sensors blare out hitting the trailer then it is not activated. If the sensors are deactivated then the D4 knows the trailer is there and all stability functions are active.

[DiscoMick]

Excuse my ignorance, but would a D4 also detect LED lights on a bullbar and activate for them?

[scarry]

Excuse my ignorance, but would a D4 also detect LED lights on a bullbar and activate for them?

On mine they are switched by relays,so no it won't detect them.

But then i don't know why it doesn't detect the relay coil?

On the D2 it used to detect them and the trailer in dash symbol used to come up.

My D4 has load resisters,which need to be turned on when needed,via a switch.

[Hugh Jars]

My MY16.5 does not sense a trailer with LEDs. Therefore, I can’t see how TSC could be activated if the car doesn’t know it’s there.
I made up the resistor pack with a switch to connect them when I’m towing.
Apparently you only need one resistor, but I’m a bit retentive and did both sides, so the trailer caption flashes with both indicators.

[Eric SDV6SE]

Excuse my ignorance, but would a D4 also detect LED lights on a bullbar and activate for them?

To my knowledge no, as the front factory turn signals are Incandescent there is already enough current draw

My BB lights are wired into the front L and R signals respectively, no issues with flicker or such.

Not sure why a bull bar would affect TSC though...

[Ferret]

Therefore, I can’t see how TSC could be activated if the car doesn’t know it’s there.

It's like DSC, depends only on how vehicle's steering, wheels and body are moving as a response to being pushed around by a trailer. It does not need to know a trailer is specifically hitched, it can feel it.

It can't use this to specifically detect a trailer is hitched because the vehicle is not pushed around by the trailer when the vehicle is stationary.

[DiscoJeffster]

Ferret, I think you missed a ‘not’ above.

Trailer Sway Assist is actually not really anything fancy. It is a byproduct of the standard stability control function which detects the vehicle yawing around the vehicle centre out of sync with the steering input.

It does NOT require the trailer to be sensed. There is a video posted on another threat which shows how it works.
The trailer being sensed allows for other functionality such as revised gearbox change ratios and minor suspension terrain assist adaptions etc.
The same indicator that would indicate stability control activation would also show if the trailer was causing it. It is via the ABS circuits to pulse the various brakes, manipulate the throttle etc. Stability control is no miracle cure, but if the traction exists underfoot then the stability control has some chance of saving you.