Thread: Towing an heavy caravan etc. Should you select Sport range?

I always use Sport mode & assist with the paddles to prevent too much speed being lost on hills while the gearbox makes up its mind about changing down.

I have installed the resistors and a switch for when towing a 2.5t camper. It does all the bits like the flashy trailer caption an reverse sensor override.

One thing I haven’t noticed is any change in shift behaviour when towing, so I tow in sport mode and use the paddles in the higher gears.

Originally Posted by Celtoid

All D4s models have LED rear lights....even from the 2009 build cars. Contrary to popular belief, it doesn't factor at all with regards to trailer compatibility.

I haven't heard of a diode doing the same job …. but that means nothing … LOL. It's just about having enough resistive load for the car to notice something is connected. It can be in the car, on the connector cable to the trailer or van or fitted to the van. A lot of guys have simply made resistor packs and connected them somewhere in series with the indicator circuit. Some people would rather not mod their car and put the resistive load elsewhere.

I bough a box from a Melbourne (?) based company that was designed specifically to do this. The advantage is that it comes with an on off switch (simple enough to fit in a home made unit too) for times that you are towing with standard globes on your trailer/van or are not towing at all.

Do you get a trailer indicator light on your dash when you indicate to turn?

I just followed the brake controller wiring instructions on the "sticky" post. This has a diode for some reason to stop a "backflow" of current. I am no electrician but I can follow instructions. I get no trailer light on my dash, but given it is the last of the D4"s perhaps all the issues had been fixed.

Dirvine and Celtoid - you are talking about different things - the diode is in the trailer brake system and has nothing to do with the trailer LED issues that the D3/D4 have.

The trailer light issue and the brake controller are different issues - you still have the trailer LED issue even if you tow a box trailer with no brake controller.

Basically the car sends a pulse down one of the indicator wires and if it detects a load from an incandescent lamp the car knows it has a trailer attached - in the D3 it switches off parking sensors, restricted height changes and lights up the trailer light on the dash. If there is a LED in the trailer lamp there is not enough resistance for the car to detect then is a trailer so not of the car actions happen.

There is a difference between the D3 and D4 and I am not sure of this difference. With the D3 an aftermarket module of resistors and relays is needed (I built my own) - in the D4 I think the aftermarket module only needs the resistors but you will have to do your own research on this.

Dirvine if you do not have your trailer light on your dash illuminate when you use your indicators with the trailer attached, then you need to check that you have genuine trailer plugs wiring in your car (and I assume you do) or you have another issue such as LEDS in your trailer and no aftermarket module fitted to account for this. The later D4s have tow assist built into the car so if your vehicle does not know it has a trailer attached because it is not getting the correct response from the test pulse then it is unlikely your trailer assist will be working.

You need to read up on this - there is plenty on the forum.

Garry

Originally Posted by garrycol

Dirvine and Celtoid - you are talking about different things - the diode is in the trailer brake system and has nothing to do with the trailer LED issues that the D3/D4 have.

The trailer light issue and the brake controller are different issues - you still have the trailer LED issue even if you tow a box trailer with no brake controller.

Basically the car sends a pulse down one of the indicator wires and if it detects a load from an incandescent lamp the car knows it has a trailer attached - in the D3 it switches off parking sensors, restricted height changes and lights up the trailer light on the dash. If there is a LED in the trailer lamp there is not enough resistance for the car to detect then is a trailer so not of the car actions happen.

There is a difference between the D3 and D4 and I am not sure of this difference. With the D3 an aftermarket module of resistors and relays is needed (I built my own) - in the D4 I think the aftermarket module only needs the resistors but you will have to do your own research on this.

Dirvine if you do not have your trailer light on your dash illuminate when you use your indicators with the trailer attached, then you need to check that you have genuine trailer plugs wiring in your car (and I assume you do) or you have another issue such as LEDS in your trailer and no aftermarket module fitted to account for this. The later D4s have tow assist built into the car so if your vehicle does not know it has a trailer attached because it is not getting the correct response from the test pulse then it is unlikely your trailer assist will be working.

You need to read up on this - there is plenty on the forum.

Garry

To add to Garry's post.
For the D4 resistors only are required. The D4 sends the same pulses to detect a trailer but only once when started or when the driver's door is open or shut (IIRC?). It does not do it continually (as a D3 does) so relays are not required.
You will only get the trailer turning light if there is resistance in that particular turning circuit. For instance I have a switchable resistor installed in the LH indicator trailer plug circuit. When turned on the vehicle detects this at startup and instigates the trailer mode. If I indicate left the trailer light will flash but if indicating right it will not.

Cheers,
Chris

In my very rusty understanding of electronics I couldn't figure how the diode would achieve anything regarding the trailer LED issue. I assumed it was relevant to the brake control unit only. Since I don't have a brake control unit fitted to my car and didn't know what the diode was supposed to be achieving, I stated that I had no idea what the diode could be doing. Wasn't about to comment one way or the other.

I've read shed loads of threads on this forum over the years on trailer assist and have seen a lot of comments stating that trailer assist works regardless of the car being aware of having a trailer fitted or not. It makes sense that it should be activated only when the car registers the trailer but that doesn't mean that's how LR achieved the outcome (car may just react to having arse end sway). Once again … can't comment.

I've a Linear Electronics box in series with my D4s LH indicator. The trailer indications works regardless of whether I indicate left or right. This I know as a fact …. I just checked . When the box is on, the car thinks it has a trailer connected …. it doesn't matter if you have or not as the car has no other way of telling.

I'm sure if LR put their mind to it, a micro in the plug coupled to some electronic magic (the car is full of the ****), would solve this problem. Why they chose not to is perplexing.

I am now completely confused. Yes I agree the diode was for the brake controller (sorry for misinformation). But after I attach my caravan, the rear parking sensors when selecting reverse do not go off. If the van is not connected via the plugs the sensors beep (even when with trailer hitch line up is selected on the camera). I have never seen an icon on the dash saying trailer connected. I have had my van swaying as some big rigs pass me and sometimes my car beeps so I presume the trailer assist etc must be working. I might see others at the WW2018 and see what they think next week.

If your rear park sensors go off when the trailer is connected and the dash symbol does not come on when you indicate then simply your car is not recognising it has the trailer fitted.

Are your trailer indicators LEDs or Incandescent - if they are incandescent then you have a wiring issue in the car. If they are LEDS then the car is not detecting the LEDs and hence the trailer - so either change your indicators to incandescent (or if you have side indicators as well change these to incandescent) or buy or make a module to correct this issue.

Garry