scautogroup

Ok Guys, I have never posted on these forums before but here goes.

I am the owner of a small used car dealership, I took on trade a 2008 GL-550. I am no stranger to tough problems with cars or spending money reconditioning the vehicles, but this one we cannot figure out, so i need some help please.

The car has a issue with the traction control light (Yellow triangle) coming on and off constantly at highway speed.

It does it almost non stop until i slow down and then lets me pick up speed again.

My mechanic has checked the system, there is no codes, I have been driving the car for almost 100 miles, replicating the issue, trying to duplicate a code and nothing will pop out.

We have drove the car with the scanned on while its blinking and it will not throw a code.

Recent work that we did, new rack and pinion, main battery, right front air strut, stabilizer bar bushings.

Note the PDC system is not working, the previous owner changed the bumper cover and the sensors are not correct so the system is inop. Apparently 2008 has 2 different bumper covers and sensors that go along with it. we tried to fix this and it just became a money pit and no solution.

Just to cross these items off the list, the tires are the correct size should be on the car. Just did an alignment after doing the rack and pinion job.

Please let me know if you guys have any recommendations or similar problems.

Thanks Martin

Carlos v Z

Did you resolve the problem?
I have exactly the same problem.
Changed wheel sensors for 180 euro a piese and much more without resolving the problem.
Also appeared after changing tires. Changed back and no result.
Esp keeps going on and off at around 100 km/h. Also test during driving and all wheels the same speed.
When the car is with all the wheels in the air the left rear wheel is turning a little bit heavier, the Mercedes dealer is saying that this is not the problem but also do not now why.
i hade at the time problems with airmatic, chanced valve block and relieve ring compressor , i have the idea the the car is not calibrated correctly, i understand the airmatic is self learning because
after about 30 km of driving everything is working normal...

greet Carlos

TX07GL450

Get a scanner that can give live data. Connect it and go to ESP system while driving the vehicle. Look at the wheel speed of all 4 wheels. One of the wheel speed could be intermittently 0ff. Most likely rear driver side. You can try swapping that speed sensor with a new one too. The speed sensor cable has weird kinks in its route and gets damaged along the life of vehicle. But do check the speed input of all 4 wheels before you start tearing apart the cable.

BlownV8

Some in the know say to only use MB wheel speed sensors. I replaced one with a cheap aftermarket speed sensor. Guess which one stopped working in less than a year? Yep, the cheap one. These are very easy to replace and you don't even need to take the wheel off to change.

Max Blast

Speed sensors failing intermittently or a wheel bearing installed with the wrong side facing out will also cause when speed reading issues.

DarthVaderpa

You should change all speed sensors before you start getting ABS Inoperative warning.

Carlos v Z

Was at Dealership who entered with star in esp program to check if all wheels run at the same speed, they confirm that all the wheels hade the same speed, what was remarkable that after he entered the esp program the esp of the car was turned off and steering was very heavy. I will try another tester to see if i can drive with car with esp car active.
the dealership wanted to change the wheel barings in the front, i really do not see why because the front wheels in air turning very easy without resistance and not making any noise what so ever.
if the dealership want to change a bearing why not left back wheel who is turning heavier.

the strange thing is that after driving 30 km there is no problem what so ever and everything is working fine.

greet and thank you for input Carlos

Carlos v Z

if the speed sensors are failing why there is no saved error when doing diagnostics with star at dealer?

Max Blast

If it's not a sensor or it's wiring connection then the next to look at is the wheel bearings. They carry the reluctor/magnet wheel that the sensor reads from, and if damaged or incorrectly installed will cause these issues.

DarthVaderpa

There are at least four codes for the speed sensor:
P0500 Vehicle Speed Sensor Malfunction
P0501 Vehicle Speed Sensor Range/Performance
0502 Vehicle Speed Sensor Low Input
P0503 Vehicle Speed Sensor Intermittent/Erratic/High

If the sensor is failing intermittent (happened to me) the code will appear and disappear if it start work properly.

alx

... but it will be stored as a small "f" in star/ das and will be readily viewable

Carlos v Z

thank you for feedback, next week will change wheel barrings and will let you now.

bobadj

The same thing just happened to me with W164: over 80 km/h blinking ESP and wont accelerate. The solution: once I turned off ESP the car was accelerating and drove normally. I drove it with esp off for some 15 kms, stopped to fill the tank, switched off the car and after I started it, havent had the issue any more. Drove some 200 kms since then and all looks normal, no blinking ESP or no acceleration over 80. Not sure, but maybe that turn off/turn on ESP thing helped.

Max Blast

Yeah but holy thread resurrection Batman, your wheel sensors are failing to read wheel speed, which triggers the drivetrain ECM to limit you from going faster than 80 litercolas to keep you from morting yourself.

You’ve just posted a lethal workaround.

Have your car read out to determine which wheel sensor is failing, which triggers the ESP off warning and in some cases heavy steering; then replace both sensors on that axle.