Removal and installation of front wheel-speed sensors - RA42001240712X(42-0712)

Preceding work:

Raise vehicle with lift platform (00-908)

Remove front wheel

Operation no. of operation texts and work units or standard texts and flat rates: 42-9801,42-9802.

1. Model 124, 201 
   Fig 1: Identifying Front Wheel-Speed Sensors Components

   Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

   Ignition	OFF  .
   Coaxial plug (L6/1x or L6/2x)	remove from bracket (46) and unplug. Before plugging back together, inspect O-ring, replacing as necessary.
   Cable (27)	remove from wheel house downwards through rubber grommet. When installing, ensure that the cable (27) is clipped in correctly. Refer to notes on wheel speed sensor.
   Self-locking hexagon socket screws (30)	unscrew, replace, 22 Nm.
   Front wheel-speed sensor (L66/1, L6/2)	remove complete with the cable (27). Before installing, coat wheel speed sensor and bore in steering knuckle (48) with Molykote Longterm 2. There must not be any metallic foreign bodies on the magnetic edge of the wheel speed sensor. Check O-ring (28), replace if required. Ensure that the flange of the wheel speed sensor abuts the steering knuckle. Do not use force.
   Wheel hub rotor	check for any damage and heavy contamination, replace wheel hub if required.
   Model 124 (except 124.034/036)  Test program	perform (42-0720).
   Model 124.034/036  Fault memory	read out, then erase (Chassis Diagnosis Manual, Volume 2).

   Notes on wheel speed sensor cables 

   The fixing points or markings of the wheel speed sensor cables were revised several times in the course of development. Since 11/89 only the 3rd version is still available as a replacement part.

   • 1st version = 1 color marking band which must be located beneath the clipping point (arrow).
     Fig 2: Identifying Clipping Point - 1St Version

     Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
   • 2nd version = 2 color marking bands. The clipping point is located between them.
     Fig 3: Identifying Clipping Point - 2St Version

     Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
   • 3rd version (since 11/89) with fixed reinforcement sleeves.

     When replacing a wheel speed sensor on vehicles built prior to 11/89 the brackets 29 and 32 together with the cable for the wear indicator (57) must also be replaced.

     Fig 4: Identifying Clipping Point - 3St Version

     Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

   A red marking arrow (cutout) has been applied to the rubber grommet to center the wheel speed sensor.

   The function and design of the wheel speed sensor has not changed.

   Fig 5: Identifying Area Applying Rubber Grommet To Center Wheel Speed Sensor

   Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
2. Models 129, 140 
   Fig 6: Identifying Axle/Distributor And Speed Sensor Cable

   Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
   Fig 7: Identifying Plug Connection Bracket And Front Speed Sensor Cable

   Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

   Ignition	OFF  .
   Speed sensor cable (55) in units compartment	separate, plug in at the right or left plug connection of the front axle/distributor (X62/6 or X66/7). Expose, route wheel speed sensor cable (55), note markings, cables should not be subjected to tensile loads.
   Wear indicator (52) plug connection	detach, attach at brake caliper (40).
   Plug connection bracket (X62/14 or X62/15)	open, close.
   Hexagon socket screws (30) of wheel	unscrew, screw in.
   speed sensor	When installing, use new self-locking hexagon screws, 22 Nm.
   Front wheel-speed sensor (L6/1 or L6/2)	withdraw vertically out of the front axle casing, plug in. Before installing, lubricate wheel speed sensor and bore in steering knuckle with Molykote Longterm 2. When installing, ensure that there are no metallic foreign bodies on the magnetic edge and that the O-ring is not damaged, replace the O-ring if required. The flange of the wheel speed sensor must abut the front axle casing. Do not use force!
   Wheel hub rotor	check for any damage and contamination, replace wheel hub if required.
   Model 129.058/063/067/076, 140  Fault memory	read out and erase in accordance with the diagnosis manual - chassis.

   On vehicles with ADS 

   The acceleration sensor (B24/1) is connected to the wheel speed sensor L6/2 (right-hand) via a sheet metal bracket. When removing the wheel speed sensor also remove the acceleration pickup, detach from sheet metal bracket and pull out of the right-hand plug connection of front axle/distributor (X62/15).

   Fig 8: Identifying Acceleration Sensor

   Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
3. Model 202 
   Fig 9: Identifying Plug Connector - Model 202

   Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

   Ignition	OFF  .
   Plug connector (L6/1x or L6/2x)	remove from bracket and unplug. Check O-ring before replugging, replacing as necessary.
   Wheel-speed sensor wire	expose, route, note markings. Do not pull on wires.
   Wheel-speed sensor Allen screw	unscrew, reinstall. Use new self-locking Allen screws for reassembly, 22 Nm
   Front wheel-speed sensors (L6/1 and L6/2)	remove and re-insert vertically at the front axle housing. Apply Molykote Longterm 2 to the wheel-speed sensor and the bore in the steering knuckle before installation. When installing, ensure that the sensor's magnetic edge is free of metallic particles, and that the O-ring has not been damaged, replacing O-ring where necessary. The flange of the wheel-speed sensor must rest against the front axle housing. Do not use force!
   Wheel-hub rotor	check for damage and contamination, replace wheel hub where necessary.
   Fault memory	read out, then erase (Chassis Diagnosis Manual, Volume 2).