Hello friends. Hoping someone can put me in the right direction. Recently, was driving and suddenly I lose traction control and ABS. The car begins bucking like a wild stallion and I had to limp home at various speeds. Sometimes I could pull over, restart the car and get everything back for a few minutes. If it failed while driving at higher speed, it would at least keep the speed but it seemed like I lost 6th or 7th gear (RPM's were spinning higher on the tach).
I've changed both rear wheel speed sensors (Bosch), cleared the codes but now, it locks up my front left caliper and I basically cannot drive the car. Both traction control lights light up and ABS light came on. Clear codes again but still persists with the locking front left caliper. I checked all ABS related fuses and they check out fine.
When scanning, it states that its permanently saved the wheel speed errors but I was able to clear the codes.
What are my next steps? After some research, I'm leaning towards either the ABS sensors on the front or rear or I've also seen that the magnet on the rear axles goes bad and can also cause the error.
Thanks for any and all help.
Get the actuation values of all 4 speed sensors and see if one of them is way off. Then, its either the sensor itself, or the ABS magnet ring. If they look accurate, then its likely the ABS module.
Tenebrae there are two pets to every wheel sensor. The sensor and the ring that causes the pulses the sensor reads.
Lien above and get a Mercedes specific scanner and check all for wheels speed to be smooth. If not the cheapest route is too replace the sensor. Then if it still fails you will need to replace the ring on that wheel.
The rear is probably the most likely to fail add it's pretty common in bad weather states and over 100k Mike's.
Get the actuation values of all 4 speed sensors and see if one of them is way off. Then, its either the sensor itself, or the ABS magnet ring. If they look accurate, then its likely the ABS module.
Just ran live data on the wheel sensors and it's picking up nothing from the two rear sensors. I just replaced them with brand new Bosch sensors. I guess this is pointing to the magnet ring....
Tenebrae there are two pets to every wheel sensor. The sensor and the ring that causes the pulses the sensor reads.
Lien above and get a Mercedes specific scanner and check all for wheels speed to be smooth. If not the cheapest route is too replace the sensor. Then if it still fails you will need to replace the ring on that wheel.
The rear is probably the most likely to fail add it's pretty common in bad weather states and over 100k Mike's.
I've seen a thread where someone replaced a rear tone ring. They unbolted the control arms from the wheel carrier and removed the wheel carrier from the car leaving the axle in the car. Slot the old tone ring to break it free from the axle. Then they tapped on the new ring. The MB manual says to NOT tap on the new ring which can damage it. MB shows a pressing tool used to install it.
Now that you have narrowed it down to the rear possible. Pull the sensor and run a magnet part it quickly to see if you have any wheel sensor readings change. If so your good wiring wise add need to change the magnetic rings.
I would suggest replacing both rear axle and both rear wheel bearings while you have it apart. Especial off there are allot of miles or snow conditions that are drove in.
I have never tested a wheel speed sensor personally. From my understanding using a multimeter you disconnect the sensor and:
- Measure the resistance of the sensor with the multimeter set to ohms. Positive to one pin of the connector and negative to the other pin. A good sensor should be reading 1000-2000ohms.
- Measure the AC voltage of the sensor the same way, set the multimeter to mv. With the multimeter connected spin the wheel/rotor and see if theres any reading change. This tests the sensor and the ring. If you see voltage and it increases as the wheel/rotor is spun then it points to an issue furhter up like abs module or wiring.
I will also add the specific fault codes you are getting can point to the issue. Recently someone with a W221 was getting the abs warning on the dash after having the suspension in the front worked on. The specific fault code was something like left front sensor open positive/ground. That pointed to either faulty sensor or wiring issue or sensor not connected. I think it turned out the sensor was not reconnected.
Another fault code could be something about implausible readings which would point more towards a faulty ring. The car recognized the sensor was connected but was not seeing wheel speed readings matching the other sensors.
I dont have 2013 manuals but from my 2010 manual its showing the sensors are wired directly to the abs unit. So it can test if the sensor is connected and if it has an open circuit.
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