** UPDATE ** PROBLEM SOLVED **
1) Put tiny small copper conductors into N47/5 connectors to improve contacts especially for the wheel sensors (36,37, 45,46)
2) Installed new cables from the sensor (L6/3) to the ESP connectors.
3) Cleaned the tone ring of the rear/left wheel with CRC Brake Parts Cleaner.
4) Erased the codes with scanner
5) So far no code no problem ^^

Thank you friends ~

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After installed new tires at Pep Boys, ABS/ESP lights came on for the first time.
Argued with them without any success.
Bought a scanner, diagnosed with and it said the wheel speed sensor #3 had an issue or check circuit.
Replaced rear/left sensor with new generic one, still issue there.
Checked actual data stream of the sensors and saw the L6/3 is not stable (stop:0.73, moving:way less than other wheels) and then
ABS/ESP light came back even after clear the DTC records after drive couple seconds.
I unplugged the N47/5 connector to test sensor circuits, measured L6/1,2,3,4 connections and seemed pretty same and stable measured 0.4M Ohm with a Fluke digital multi meter.
Now I shunt the L6/1 and 3's lead-#2 to see if the EPS detects the circuit issue.
Oops! Now problem is getting worse.
Now L6/1 also got an issue as soon as you turn on the vehicle without ignition, and L6/3 issue comes on after couple yard driving, then the vehicle gone to limbo mode, you know
RED break warning, no steering support.
Wheel sensor readings from the scanner said the L6/1 is stable 0.73 and no change, while other sensor readings change when the car is moving, means circuit #1 has an issue.
After couple yard moving, L6/3 error also popping up, then limbo mode.
Read an article saying the connector is very fragile so the each contacts of the connector can easily damaged. Please advise... if you can check the bad contact, and can fix the problem.. FYI I got brand new L6/1 sensor for potential replacement.

 

I would load test battery and terminal connections first before playing with sensors.

 

Any update on this? We have an intermittent ESP issue with our GL550 that the Dealer has yet to be able to fix. There are no codes, etc.

 

I would recommend to clean the tone ring with brake parts cleaner before anything.

 

Will do, that seems like a good idea.

 

Have your battery load tested before you even do that