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Flashing Yellow Triangle supposedly after Wheel Change ML320 W164
Hi all,
New to the forum. Just bought a 2008 W164 ML320 AMG.
I believe the car originally had 19" wheels which have now been replaced with 20" wheels.
New tyre sizes are Fronts: 265/45/20 and rear 275/40/20.
I get the flashing yellow triangle indicating a traction fault but definitely not a genuine traction issue i.e no wheel slippage or spinning. My first thought was wheel speed sensor going bad. However, the seller is adamant that the fault is to do with the new wheels and was fine before - Interestingly if you drive for a few miles sub 45mph and then accelerate up to normal speeds, the fault never reappears after that until you turn the car off and on again, which suggests some sort of automatic calibration happens and not the wheel speed sensor at fault. Obviously this is not practical longer term.
Has anyone ever experienced this or know the fix? - Image attached incase it helps!
The system tracks speed at each wheel and expects them to be the same. That's why each wheel has its own speed sensor and its how the traction system works. If one wheel is rotating at a different speed, say by slipping, it will adjust for that by retarding engine power and/or applying the brakes. Your problem is that you now have 2 wheels rotating at a different speeds all the time, so the ecu is trying to rectify that difference. That's what's triggering the tranction control system and giving you the yellow triangle on the dash. Changing the tyres to ones with an inconsistent diameter is your problem. The only solution is to have 4 tyres of equal diameter. Two of your tyres have a diameter of 119mm and 2 have 110mm. That small difference probably isn't noticeable at low speed but becomes pronounced at higher speeds. Unfortunately, the seller is most likely 100% correct.
Also, you'll be stressing the driveline and transfer case with this setup even if its not noticeable. I assume that you had the tyres fitted by a shop? Didn't they warn you of this, because they should have.
Last edited by BlackML550; Nov 2, 2023 at 03:09 AM.
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