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 )
Time:2-3 hours
Repair Cost: DIY Cost – Less than $20 

Parts You’ll Need:

• ML ABS Bearing
• 12mm x 5 mm x 5 mm Carbon BrushesBackground

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. 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.
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.

Conclusion

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

HINTS:

• • 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

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