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ABS ETS BAS 4ETS Problem DIY Repair Instructions for Mercedes Benz

STAR Diagnostics: C1401 High-Pressure Return Pump Circuit Open/Shorted; Will Not Shut Off

Difficulty:  6  (1 being easy and 10 being hard )
2-3 hours
Repair Cost: DIY Cost – Less than $20 

Parts You’ll Need:

Your ABS/ETS/BAS lights just came on your Mercedes Benz, and you almost had a complex attack. Don’t panic. There are a few reasons why you see these lights, and you can do some of those repairs yourself.

Possible causes for ABS ETS BAS light are:

  • Bad Brake Switch
  • Defective Speed wheel sensor
  • Failed Relay K25
  • Bad ABS Motor (4ESP)

This DIY article will focus on repairing the ABS motor (4ESP). This repair could cost around $3,000 at the dealer or around $2,000 at an auto repair shop. If you have DIY repair skills, you are looking at about $20. That’s right, $20.

This is a very common problem on ML W163. A couple of years ago, I posted this solution on a Mercedes Benz forum, and I am glad to see that it has helped many people. Even though other models are not affected as much, this fix applies to any other Mercedes Benz model. Even to others makes, for that matter.

Diagnostic Steps:

    1. Locate the ABS pump on your Mercedes Benz. On the ML, it is located on the front left behind the driver’s side headlight, next to the washer fluid reservoir.
      View the Location of the ABS Pump on W163
    2. Find the relay that runs the ABS pump. If you look at your fuse box, it will be marked ABS Pump or ABS Motor or 4EPS.
      On the ML W163, it is K25. Located under the hood, in front of the driver.
    3. Manually get the ABS motor to run by jumping the wires on the ABS Relay socket.

  1. If the ABS motor doesn’t run when you jump the relay, move to the next section.

DIY – ABS Motor Repair Steps

  1. Disconnect battery.
  2. Remove the driver-side front wheel and wheel liner for access on the ML. Another alternative would be to remove the reservoir to get some space to take out the ABS pump.
  3. Unscrew the bolts that hold the pump to the ABS control valve unit—two T25 torx bolts on each side of the motor in the ML. Be careful not to strip them. They strip easily, don’t ask how I know.
  4. Pull the ABS motor straight out. An O “cap” metal ring is at the ABS module’s center. Be careful not to pull that out with the ABS motor. If you pull the ABS motor ½ inch out, put a long screwdriver in the gap pointing toward the shaft. This will help and will avoid the cap coming out with the motor.
  5. Remove the rotor from the motor housing. A couple of methods:
    1. Use a flathead screwdriver to remove the black plastic from the metal motor housing. Once the central piece is loose, you must pull hard to remove it. The magnet inside will want to hold the rotor in place.
    2. Put the shaft on vice, and make sure you do not damage the shaft by over-tightening it. Pull on the motor.
  6. Use a puller to remove the bearing on the ABS motor. I reused mine. If you need one, you can use NAPA 6001-2RSJ or 6001ZZE Nachi Bearing Shielded C3 from Amazon.
    You can rent this puller from Advance Auto Parts or AutoZone or be creative when removing the bearing. Or you could also purchase one on Amazon.puller
  7. Inspect the brushes and replace if necessary. Remove the old brushes. Cut the copper braid flush with the surface of the old brush. The old brush will pop out. Cut the other end of the copper braid around 1/4″ from the support molded into the plastic cover on each side. These brushes are completely gone.
  8. Install new brushes.
  9. Reinstall in reverse order.
  10. Last step: Start the car and turn the steering wheel clock to clock a couple of times to reset the lights.


The repair is very straightforward but requires a certain level of experience. If you feel uncomfortable doing this repair, consider just removing the ABS motor and sending it in for repair to any of the Mercedes-Benz ABS pump repair service


    • You can rent the following bearing puller in the picture from Autozone.
    • The magnetic field will pull the rotor back to the housing. Try not to damage the jelly O-ring, which insulates the rotor and the housing.
    • Can the car be driven without the pump while I work on it? Though we strongly would NOT recommend this, you can drive the truck without the pump. At your own risk!
    • What are the part numbers of the brushes, and where can I get them?
    • Applicable Part Number (there could be more): A 163 545 97 32 A 163 431 07 12

Troubleshooting Mercedes-Benz ABS, ETS, BAS, & 4ETS Problem

YOUCANIC full system diagnostic scanner is a powerful tool that can help you troubleshoot Mercedes-Benz problems quickly and efficiently. This scanner can communicate with all the control units in your Mercedes-Benz, including the engine, transmission, ABS, SRS, and more. By accessing real-time data from these control units, you can pinpoint the root cause of the problem and take appropriate action to resolve it.

Whether you’re experiencing issues with your engine, transmission, or other systems in your Mercedes-Benz, the YOUCANIC diagnostic scanner can provide valuable insight into what’s going on under the hood. This scanner can help you identify error codes, read live data, and perform special functions like reset adaptations or component tests. With this information, you can make informed decisions about repairs, maintenance, and upgrades to keep your Mercedes-Benz running smoothly.

Overall, the YOUCANIC full system diagnostic scanner is invaluable for any Mercedes-Benz owner or technician looking to troubleshoot problems quickly and accurately. With its user-friendly interface and powerful diagnostic capabilities, you can save time, money, and frustration by diagnosing and resolving issues with your Mercedes-Benz quickly and efficiently.


  1. Wow . Thank you for this fix. Works great.
    Saved a load of cash!!

  2. My ML350 2003 warning light keeps coming on and the car feels like its braking itself when i put the throttle down.

  3. WOW! Right on the money! 2002 W163 ML500 All Wheel Drive. My ABS Pump Motor keeps running even after the vehicle is turned off for a long time. The ETS ABS yellow lights come on while Im driving and the ABS Module makes a demon like humming sound. I followed the instructions here and it all stopped when I replaced the RELAY. Just for fun Im going to remove the motor and inspect. Already ordered the bearings and brushes.

  4. Just fixed my pump. Thank you!

  5. S Finn Terje Bruvoll

    just did this repair on my ml 270 2001. and it works!! thank u..
    problem finding exact right brushes,in local stores. But found some bigger and just sanded them down

    • I checked and the motor is ok but system not functioning and ETS and ABS lights are on. brake switch is ok. cruise control is working by the way.

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