VOLVO
CEM-B103D86 - Right Headlamp Control. Bus Signal / Message Failures. Signal invalid
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
9 modelsS60 (2011–), S80 (2007–), V40 (2013–), V40 Cross Country (2013–), V60 (2011–), V60 Cross Country (2015–), V70 (2008–), XC60 (2009–), XC70 (2008–)
What does this fault code mean?
Messages between the central electronic module (CEM) and the right main headlamp control unit (RHCU) are missing or incorrect on the LIN bus. The fault code is then stored, and the headlamp adjustment may be affected. The fault may lie in connectors, the bus, the supply, the earth or the control unit.
Possible causes
- Contact resistance, oxidation or loose connections in connectors or joints
- Break in the communication bus to the right main headlamp control unit
- Break in the voltage supply or earth connection to the control unit
What you can do
- 1With the ignition off, check the connectors and wires to the right headlamp for breaks, looseness and corrosion
- 2With the ignition off, use a multimeter to check whether the earth connection to the right headlamp is intact
- 3With the ignition on, use a multimeter to check whether the supply to the right headlamp has voltage
- 4Clear the fault code and road test to see whether it returns
- 5If the fault remains, have a workshop check the communication and the right headlamp control unit
Symptoms you may notice4
- Side adjustment of the right headlamp does not follow the steering wheel correctly, or does not work
- Height adjustment of the right headlamp is wrong or does not work
- A message appears in the information display
- Main beam with automatic high beam control does not work
What the fault can affect2
- The light range is held in a fixed setting
- Side adjustment freezes in the straight-ahead position
General guidance for car owners. Diagnosis on the car can point to a different cause.