DSC towing problem

[pamax]

have a disco 3 2007 tdv6se with air suspension and i tow a 2.6 tonne 20ft caravan no problems on the highway but as soon as i hit a hilly winding road the dsc light starts flashing especially when coming downhill around tight corners the warning light flashs and then goes out every thing is normal but i have had the system break down completely twice once when towing up a rather long steep hill got three parts the way up and all the bells and whistles came on no suspension, transmission fault have had the auto box serviced since. the second time it happened i jumped on the brakes when traveling at around 50kph and the same thing came in only happens when towing have tried all sorts of speed and corners without the van no problems have no trouble rectifying the problem so far simply turn the vehicle off leave for a couple of minutes and the computer resets itself and away i go has anyone had this happen to them do i have to replace the air bag suspension being a newby to land rover i was impressed to stsrt with now beginning to wonder

[Graeme]

Does the car lurch when cornering with the van? Perhaps the shocks are worn-out but check the ball loading and the van loading generally for heavy weights front and rear.

[pamax]

Does the car lurch when cornering with the van? Perhaps the shocks are worn-out but check the ball loading and the van loading generally for heavy weights front and rear.
hi graeme when travelling on winding roads yes the unit does lurch van may be a little overweight but when travelling uphill its in a straight line

[Graeme]

Do you see the DSC light coming on when going uphill?

[BrianElloy]

Does the trailer dash light illuminate when you indicate?

Reason why I ask, is that of not then the car is not recognizing the trailer probably because of LED lights not providing enough resistance

This will prevent the car from going into tow mode which affects DSC, gearbox shift patterns etc.

You’ll need one of these (or equivalent) to remedy

LED Tow Connect - Tow LED Fitted Trailers Safely: Discovery 4 (http://www.ledtowconnect.com/2012/06/discovery-4.html'm=1)

[austastar]

....... probably because of LED lights not providing enough resistance


Hi,
I suspect the wording should be that the led lights have too much resistance and not providing enough current draw to trigger the 'trailer mode'.
However, when not braking, indicating or using lights, the caravan lighting circuit does not drawer power. So there must be something else to tell the vehicle a trailer/van is being towed.
Someone more knowledgeable than me may be able to explain what is happening.
Cheers

[DiscoJeffster]

Do you have enough trailer braking engaged? It sounds like the trailer is pushing on the vehicle while it’s turning going downhill and possibly the yawing the vehicle as it senses the load of the trailer and is causing DSC engagement.

Maybe try enabling more trailer brake and see if that changes the car’s attitude and DSC activation. It should not do it.

[Graeme]

However, when not braking, indicating or using lights, the caravan lighting circuit does not drawer power. So there must be something else to tell the vehicle a trailer/van is being towed.
A D3 pulses the trailer blinker circuits at regular intervals looking for load on the circuits to indicate the presence of a trailer. A D4 pulses the trailer blinker circuits every time the driver's door is closed.

[Eric SDV6SE]

1. You are required by law to have a braked trailer if the trailer mass is in excess of 750kg. You can either have hydraulically braked trailer via the hitch, or the more popular electric brakes, in which case you need an electronic brake controller in the car, either the RedArc or Tekonsha P3 are good examples. These are relatively cheap and easily retrofitted by an autorlectrician or a handy DIYer.

2. The D4 (maybe D3 too) sends a signal down each indicator wire roughly every second or so (could be more often, I can't exactly remember) when towing. If the resistance is high enough (I.e. your trailer lights are or have been on), the car knows it has a trailer attached and adapts the DSC, ESC throttle and braking systems accordingly. it also cancels the reversing sensors and the auto levelling feature of the suspension. Even when driving without lights on, each time you signal, the trailer status is reconfirmed. So when you first hook up and plug in and do your light check, the car knows it has a trailer on.

3.however, the system appears to be designed for incandescent lights, in t that these draw more current than LED, so what a lot of people have experienced is that when towing a trailer with led lights, the car doesn't know it's towing and so the DSC, ESC etc are not modified. This can cause unpredictable handling and the car to fault.

The common solution is to fit load resistors either at the trailer lights, or into the wiring harness for the rear plug. This increases the line load so that the car detects it has a trailer on.

Also check your down load on the hitch at the car, if the van is not correctly loaded or too heavy, you'll have too much downward load, leading to instability when towing, worse downhill.

From memory (others here that have far more knowledge on this than me may be able to help further) I believe you are allowed a max downward load of 10% of the maximum towing capacity, so for D3/D4 this is 350kg.

Hope this helps

[coopers1969]

I remember the first time I towed with my D3 and I didn’t have the setup that the car recognised I had a trailer on OMG it was a nightmare when I got to camp I fixed that issue let me just say the trip home was a lot more calm. The car changes a lot when towing if it knows there is a trailer behind you. Make sure when indicating you see the little trailer light up on the dash.

[Graeme]

it also cancels .......the auto levelling feature of the suspension.
It does not cancel auto levelling, only auto height change to off-road height for those modes where off-road height is normally auto selected. Auto levelling is why air suspension is so beneficial when towing.

[Geedublya]

Check tyre pressures of both car and trailer as well. I found my D3 DSC to be a lot more sensitive than the D4 DSC when towing. The D3 would trigger very easily.

[Markus1]

Argg. I didn't realise it stops auto suspension height. Does this mean you also can't manually select off-road height?

Just about to embark on a trip in a week's time. Better pull the camper out for a full test to see what the heck I don't know.

[disco4now]

Argg. I didn't realise it stops auto suspension height. Does this mean you also can't manually select off-road height?
You can select off-road high no problem. Its the thing when you select Mud/Ruts etc and it automatically puts in in off-road for you that is suppressed when a trailer is attached.

[DiscoJeffster]

Argg. I didn't realise it stops auto suspension height. Does this mean you also can't manually select off-road height?

Just about to embark on a trip in a week's time. Better pull the camper out for a full test to see what the heck I don't know.

You misunderstand. It will let you MANUALLY select any mode. It will also re-level itself when the weight of the van is added or subtracted. What it won’t do is AUTOMATICALLY select extended height when you enable ‘rock crawl’ (which is the default mode of operation) according to the post above. This is actually new to me as I’ve not noticed this.

[Markus1]

Thanks DJ. Blood pressure just dropped 10 points.

[Graeme]

What it won’t do is AUTOMATICALLY select extended height when you enable ‘rock crawl’Off-road height, not extended height. Extended height is when the vehicle becomes grounded then super-extended height when the brake pedal is used to go higher still.

The OP's D3 has a problem going uphill but that may be unrelated to his DSC activating.

[BobD]

As Graeme said, DSC operating in corners to stabilise the car is what it is designed to do. With your caravan on it is activating as necessary due to extra loads put on the car. You may find that the front wheels are tending to lose grip both in acceleration and cornering, which will cause DSC to activate and stabilise things.

The issue of the errors when towing up hill is not the DSC. It is some sort of problem putting the car into restricted performance mode, as evidenced by the warning messages. It is not DSC that causes that.

[Eric SDV6SE]

It does not cancel auto levelling, only auto height change to off-road height for those modes where off-road height is normally auto selected. Auto levelling is why air suspension is so beneficial when towing.

To clarify my comment Graeme. My understanding is that with a trailer connected correctly, the AS will not autolevel once the car is stopped and doors are closed, as it tends to do during normal non towing driving.

During normal towing, the car does autolevel, you are right.

Suspension height selection still works, albeit manual selection.

I've tested this by leaving the umbilical disconnected so that the car doesn't "know" it's towing, when stopped and all doors are closed, the car auto levels. Plug the umbilical in, the dash indicator flashes, drive a bit then stop, the car does not autolevel.

[pamax]

Do you see the DSC light coming on when going uphill?
thats a no graeme the whole system crashed only the once uphill after it reset no problems until the winding downhill roads dsc flash on then off and carry on as per normal

[Graeme]

I've tested this by leaving the umbilical disconnected so that the car doesn't "know" it's towing, when stopped and all doors are closed, the car auto levels. Plug the umbilical in, the dash indicator flashes, drive a bit then stop, the car does not autolevel.Perhaps the extent of auto levelling is reduced to reduce compressor running with possible extra weight on the rear.

[pamax]

Does the trailer dash light illuminate when you indicate?

Reason why I ask, is that of not then the car is not recognizing the trailer probably because of LED lights not providing enough resistance

This will prevent the car from going into tow mode which affects DSC, gearbox shift patterns etc.

You’ll need one of these (or equivalent) to remedy

LED Tow Connect - Tow LED Fitted Trailers Safely: Discovery 4 (http://www.ledtowconnect.com/2012/06/discovery-4.html'm=1)

hi brian do not have the trailer light on dash and i have noticed that when the caravan is hooked up and the lights turned on the blinkers flash on and off at a rapid rate and not very bright turn the lights off every thing is ok so i am tending to nagree with you about the tow connect any ideas on where to get a reasonably cheap one cheers pamax

[BobD]

Blinkers flashing fast and dull with the lights turned on is not a symptom that the car is not recognising the trailer. There is something wrong with the wiring if that is the case. It may have a poor earth or you may be sending your tail light signal to the brakes on the caravan if you haven't specifically wired it for the D4 as per other posts on the forum.

The D4 won't recognize the trailer if you have LED lights because the current draw is too low, not too high. Dull lights and fast flashing means the current draw is too high. The fix for LED lights is to wire a 21W resister into the indicator light circuits on the trailer, which is very cheap. You don't need a pulse shunt module. That is only required for a D3, whatever the add says.

[BrianElloy]

I agree with Bob. Something not right there ..

Need to resolve that first before you get an LED module

[Pedro_The_Swift]

Does a D3 cutout from overboost?

[pamax]

have a disco 3 2007 tdv6se with air suspension and i tow a 2.6 tonne 20ft caravan no problems on the highway but as soon as i hit a hilly winding road the dsc light starts flashing especially when coming downhill around tight corners the warning light flashs and then goes out every thing is normal but i have had the system break down completely twice once when towing up a rather long steep hill got three parts the way up and all the bells and whistles came on no suspension, transmission fault have had the auto box serviced since. the second time it happened i jumped on the brakes when traveling at around 50kph and the same thing came in only happens when towing have tried all sorts of speed and corners without the van no problems have no trouble rectifying the problem so far simply turn the vehicle off leave for a couple of minutes and the computer resets itself and away i go has anyone had this happen to them do i have to replace the air bag suspension being a newby to land rover i was impressed to stsrt with now beginning to wonder


HI all thank you for your replies and advice fitted a tow connect to the caravan now the trailer light flashs with the blinker but when i turn on the headlights the blinkers pulseate without turning them on the same thing happens when the brake lights are applied i have hooked the van up to another tow vehicle and no problems so have looked at the earth on the car unless there is more than one i have hit a dead end i have thought of replacing the leds on the caravan but the clearance lights make this difficult the leds look as if they are a sealed unit and stuck on the caravan any suggestions cheers pamax

[Graeme]

Is your Tow Connect for a Discovery 3?

[BobD]

Is your Tow Connect for a Discovery 3?

And is the trailer brake controller in your car correctly wired in accordance with the sticky on the forum? It is not the same as other cars so if the trailer lights work on another car it is likely that your D3 trailer brake controller is not correctly wired. If wrong, the trailer brake will be connected to the car tail lights and turning on the headlights will operate the brakes on the trailer.

Since both brake lights and headlights are not working correctly there is a high probability that the brake controller wiring is incorrect for a D3.

By the way, the advice was NOT to fit the tow connect until the wiring was sorted out because the LED lights were not the cause of your problem.

[pamax]

Is your Tow Connect for a Discovery 3?
yes graeme the paper work says it is the trailer lights on the dash works with the blinkers have checked plugs cant get into lights to check them but if the system works on another vehicle with no problems i feel it could be the d3 will check the brake controller but it seems ok with it all working

[pamax]

Blinkers flashing fast and dull with the lights turned on is not a symptom that the car is not recognising the trailer. There is something wrong with the wiring if that is the case. It may have a poor earth or you may be sending your tail light signal to the brakes on the caravan if you haven't specifically wired it for the D4 as per other posts on the forum.

The D4 won't recognize the trailer if you have LED lights because the current draw is too low, not too high. Dull lights and fast flashing means the current draw is too high. The fix for LED lights is to wire a 21W resister into the indicator light circuits on the trailer, which is very cheap. You don't need a pulse shunt module. That is only required for a D3, whatever the add says.



it is a d3 bob purchased a module and it seems to have helped a to certain extent but the blinkers keep pulseating when i turn on the lights it does seem to affect the cars performance it tows really well it just restricts my abilty to tow of a night

[BobD]

it is a d3 bob purchased a module and it seems to have helped a to certain extent but the blinkers keep pulseating when i turn on the lights it does seem to affect the cars performance it tows really well it just restricts my abilty to tow of a night

Yes, I realize that and have now changed my post. Sorry about the misleading post. See the later one today which is relevant to your problems, as is the one you have quoted, apart from the fact that D3's actually do need the module to stop the pulsing indicator lights and get the car to recognize the trailer, unlike a D4.

What is your answer to my later post today re the correct wiring of the brake controller? Are your trailer brakes working correctly when you put your foot on the brake in the D3? As I said, none of the problems you have listed are because the trailer has LED lights, apart from the lack of the trailer symbol flashing on the dash.

[Graeme]

Do the van's brakes activate when you switch on parkers or headlights? If so the the car's wiring harness behind the left tail-light hasn't been modified for Australian trailer/van wiring.

[shanegtr]

Does a D3 cutout from overboost?Certainly does. My 05 D3 shows overboost and goes into limp mode when towing if im not careful. Happens most often when changing down gears under load - i now manually swap cogs when towing and back off a bit when changing gears and it minimises the limp home mode popping up at an inconvinent time. Must be getting a tired turbo so will need to replace it one day (actuator moves nice and smoothly and is not jamming or sticking).

[Eric SDV6SE]

Shane,

Have you checked the o ring seal between the intake plenum and throttle body? This I've found is a very common cause of restricted performance issues.

[pamax]

Yes, I realize that and have now changed my post. Sorry about the misleading post. See the later one today which is relevant to your problems, as is the one you have quoted, apart from the fact that D3's actually do need the module to stop the pulsing indicator lights and get the car to recognize the trailer, unlike a D4.

What is your answer to my later post today re the correct wiring of the brake controller? Are your trailer brakes working correctly when you put your foot on the brake in the D3? As I said, none of the problems you have listed are because the trailer has LED lights, apart from the lack of the trailer symbol flashing on the dash.


hi bob the brakes on the van work ok the only problem is with the lights turn on the headlights the blinkers pulsate hit the footbrake and the blinkers pulsate have checked the wiring twice fitted a module..question if i replace the two taillights with normal lights will this fix the problem taking into consideration the clearance lamps are all led but work ok no flashing pamx

[Graeme]

Are you sure that you got a D3 version of the module, not a D4 version? Without knowing what's inside their D3 version of the module, a D3 module needs to have relays for the blinker circuits because relays won't be switched on by the short test pulses, only by the proper blinker switching. D4s don't continuously test the blinkers so a D4 module does not need relays. If your module is a D4 version then it is not suitable for your D3.

The relays don't have to be mechanical, they can be electronic providing the electronics in the module ensure that the pulse is not just a short test pulse before switching on the electronic relay.

[shanegtr]

Shane,

Have you checked the o ring seal between the intake plenum and throttle body? This I've found is a very common cause of restricted performance issues.
No I havent, will definatly be worth a look. End of the day I havent gotten to worried about it yet as it doesnt fault when Im not towing

[DiscoJeffster]

No I havent, will definatly be worth a look. End of the day I havent gotten to worried about it yet as it doesnt fault when Im not towing

Smoke test is your friend. Sounds like a leak to me. My split throttle body only ever gave me grief when towing too, until it finally gave out

[Redback]

Trailer assist is mechanical and doesn't need the wiring of the trailer to connected, so you can rule that out if you have a D4, also to stop the issue of LEDs on the trailer in the D4, just turn your lights on and everything will work normally except the trailer symbol on the dash.

The issue will be the trailer not set up properly or the suspension on the car is shagged.

Probably not any help to the OP but just a heads up for those with TSA.

Trailer Stability Assist
YouTube (https://www.youtube.com/watch?v=JyNjRq46lDs)

[pamax]

have a disco 3 2007 tdv6se with air suspension and i tow a 2.6 tonne 20ft caravan no problems on the highway but as soon as i hit a hilly winding road the dsc light starts flashing especially when coming downhill around tight corners the warning light flashs and then goes out every thing is normal but i have had the system break down completely twice once when towing up a rather long steep hill got three parts the way up and all the bells and whistles came on no suspension, transmission fault have had the auto box serviced since. the second time it happened i jumped on the brakes when traveling at around 50kph and the same thing came in only happens when towing have tried all sorts of speed and corners without the van no problems have no trouble rectifying the problem so far simply turn the vehicle off leave for a couple of minutes and the computer resets itself and away i go has anyone had this happen to them do i have to replace the air bag suspension being a newby to land rover i was impressed to stsrt with now beginning to wonder




hi all have solved the problem with my lighting problems when towing after trying a tow connect led module and restrictors with no good results i changed the led taillights for normal globe types and walla no problems trailer symbol lights up on dash no pulsating blinkers everything appears normal will test out next month with a long trip coming up cheers pamax