Traction control warning light

[Cashwowud]

Hi guys,
2005 SL 350 58K Miles

Am currently on holiday in the South of France. The yellow traction control warning light sometimes flickers on a couple of times when I am going downhill and round a bend at the same time, accompanied by a small jolt coming from the rear. I've never seen this before having owned the car since 06 - the only change I made before setting off were two new Dunlops on the back. Anything to worry about?
Thanks in advance

cashwowud

 

[DSM10000]

The jolt is probably the brakes being applied to help control the car as it corners. The Traction control system and Stability control system work in conjunction with input from lateral, yaw and pitch sensors and if the sensor values suggest that the car is in danger of skidding etc then the brakes at opposite ends can be applied, throttle closed etc. A strong camber to a road can also upset the balance of the car and may trigger the Stability program.

Are you carrying heavier loads? are your tyre pressures correct for load?

 

[Cashwowud]

Thanks for your quick reply DSM. I'll certainly check the pressures but they were correct when we set off from Lancashire on Friday. Come to think of it the light and jolt happen on a cambered corner, (think mountain pass) but we have done this trip many times and this is the first time it's happened. It has happened with the boot both full and empty.

cashwowud

 

[OneForTheRoad]

Any loss of traction will flicker the light.

 

[MrRight]

but equally what model front tyres does the car have. are they the same brand and model as the rear tyres ?

i had bought myself an old car which had one winter tyre on it alongside 2 other chinese brands being accelera and potentum and the dash warning lights would turn on like a disco night club after a couple of minutes of driving. ABS, Traction control, DSC would all turn off . i had initially planned to do some burnouts to wear the tyres out before changing them but the guilt of leaving tyre marks on the road disuaded me from doing so. In the end i got the steering angle sensor reset and immediately put MP4S tyres on all 4 corners and the car doesnt misbehave anymore . those old rear tyres all had plenty of tread left but they had to go ...

 

[PobodY]

Similarly; my traction control used to kick-in quite often with the old PS3s on it, nad had a habit of cutting the power on me when I tried to take a tight left turn up a hill near home.
PS4s have stopped it... but also if I think it's going to want to interfere, I tend to turn ESP off until I've made the manoeuvre.

On that basis I'd expect to see my traction control light flickering if I was negotiating hair-pin turns.

If you really want to see it light up like a Christmas tree, try driving in Lapland.

 

[Bellow]

the only change I made before setting off were two new Dunlops on the back. Anything to worry about?

There is a high chance the above (due to discrepancy in rolling radius between existing front tyres with some wear and the new rears) is causing your problem. I have had exactly the same happen and an ECU reset cured it. Reset in my case by disconnecting the battery for 10 seconds and reconnecting. Your car may require (or have) an alternative reset method in which case use it as battery disconnects reset everything adaptive, and delete error codes.

 

[DSM10000]

If the rear tyres generate being new more grip than the front then the relative slip angle at the front (compounded by the loading from driving downhill and on a camber) may be causing the symptoms you describe.

 

[Cashwowud]

Hi and thanks for the replies. The car was fitted with Dunlop SP Soprts from new and I have stuck with the current version ever since - replacing one axle at a time and putting the new set on the back. If it's only a tyre problem then I can put up with this - i just don't want to be doing damage to the transmission with another 2000 miles to go before I get home.

 

[Bellow]

Downhill, weight on the nose and off the tail will further exacerbate the difference in rolling radius.
If you are confident that disconnecting the battery for 10 seconds won't cause any other headaches (being some distance from home) just do that and the ECU will be reset. If the problem persists - then not due to rolling radius differences but something else.
If a tyre issue, then no harm will accrue from driving but I really did not enjoy unnecessary ESP intervention destabilising the car when it was otherwise perfectly stable. How a required ESP intervention would be I do not know but the thresholds are now compromised.