Thread: Trailer Stability Assist stuck on

Originally Posted by mijango

I just tried checking the fuses and strangely can't find one for the trailer stability assist. I checked all the other fuses that are related to the trailer tho.

Furthermore, Ayers Auto have had the car today and are originally diagnosed the problem to be in the TSA loom. They have now replaced the trailer module and spent 5hours diagnosing only for me find out problem still remains.
They did mention it was fixed (ie parking sensors working) tho when my wife reversed it out of the garage, the sensors stopped working again.
$840 for nowt!! Grrr..

That's because it's not electronicly operated, Trailer assist doesn't need the trailer electrics to be connected to work, so the trailer symbol on the dash means nothing in regards to Trailer Assist.

See here
[ame="http://youtu.be/5aDTvql4OYk"]Land Rover Discovery 4 Trailer Stability Assist Video - YouTube[/ame]

Originally Posted by Graeme

As I understand it, the only definite information is that the rear parking sensors aren't working when they should be. I would persue a probable wiring fault with the sensors, possibly behind the bumper. I would take it back to where it was attempted to be repaired to ask them to have another look because I would expect some warranty on the work done. My D4 had an intermittent fault caused by a short circuit on a sensor wire that had rubbed on metal.

That's pretty much the avenue Ayers have been pursuing but when the IID tool said BOTH front and rear parking sensors were faulty it seemed odd and we assumed (wrongly) replacing the module would fix it.
My gut still tells me there is something in the computer system that thinks the trailer is attached. (Although that said, that wouldn't explain the fault message

When I do reverse I get a longish beep, the parking sensor button flashes and then goes quiet. If I try to push the button to turn it on, nothing. The key though is that I'm sure the gearing is different ( especially when coasting slowly and then accelerating) which feels jerky as the gears change down earlier.

Part of me wants to go back to the main dealer at Artarmon!

Originally Posted by mijango

That's pretty much the avenue Ayers have been pursuing but when the IID tool said BOTH front and rear parking sensors were faulty it seemed odd and we assumed (wrongly) replacing the module would fix it.
My gut still tells me there is something in the computer system that thinks the trailer is attached. (Although that said, that wouldn't explain the fault message

When I do reverse I get a longish beep, the parking sensor button flashes and then goes quiet. If I try to push the button to turn it on, nothing. The key though is that I'm sure the gearing is different ( especially when coasting slowly and then accelerating) which feels jerky as the gears change down earlier.

Part of me wants to go back to the main dealer at Artarmon!

The only way the system senses the trailer is there, is if the trailer is attached to the car.

Baz.

Originally Posted by Redback

The only way the system senses the trailer is there, is if the trailer is attached to the car.

Baz.

I'm trying to work out what it is that senses a trailer is attached. Is it the weight on the hitch? Or the electrics being plugged in?

Originally Posted by mijango

I'm trying to work out what it is that senses a trailer is attached. Is it the weight on the hitch? Or the electrics being plugged in?

The car senses the extra current draw of the trailers indicators to tell it that it is attached.

Originally Posted by mijango

When I do reverse I get a longish beep, the parking sensor button flashes and then goes quiet. If I try to push the button to turn it on, nothing.

Typical of a fault, probably short circuit, in the rear sensor wiring. No beep occurs when selecting reverse when it detects that a trailer is attached.

Edit: Front and rear sensors are controlled by the one park assist module. Trailer assist is a function of the ABS module. I suspect that the park assist module was replaced.

Originally Posted by mijango

I'm trying to work out what it is that senses a trailer is attached. Is it the weight on the hitch? Or the electrics being plugged in?

Originally Posted by Basil135

The car senses the extra current draw of the trailers indicators to tell it that it is attached.

No to both, you need to watch the video above that I posted to clarify my statement, watch it all and listen to what he says at the end, it's only 56sec

Baz.

Originally Posted by Redback

No to both, you need to watch the video above that I posted to clarify my statement, watch it all and listen to what he says at the end, it's only 56sec

Baz.

Yes Barry is correct, the trailer electrics do not need to be plugged in for TSC to work - it is a function of the ABS Module as Graeme has stated.

As I understand it, when the electrics are plugged in the engine and gearbox dynamics are changed to accommodate the additional weight being towed and rear sensors turned off all of which is indicated by the blinking symbol on the dash.

So, if you have hard wired resistors into the car to account for LED lights on your trailer and have not provided away to switch them out of the circuit when the trailer is not attached then that would cause the issue too.