Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Steering Column Tube Module Control Unit, Component Description - GF54.21-P-6051RRM
Model 190 As Of 12/1/18
As Of Model Year 2019
Location
The steering column tube module control unit is located directly behind the multifunction steering wheel (MFL) on the steering column tube of the steering column.
Tasks
The steering column tube module control unit has the following tasks:
- Reading in of sensors and signals
- Evaluation of input factors
- Actuation of components
- Sending signals
Reading in of sensors and signals
The input factors are read in via the following connections:
- Direct line
- Steering wheel CAN (CAN LR)
- AMG FlexRay (Flex AMG)
Direct line
The signals from the following components are read via a direct line:
- Steering wheel angle sensor (N49)
- Combination switch (S4)
- Steering column adjustment switch (S59) (with CODE P64 (Memory package))
Steering wheel CAN
The steering wheel electronics (N135) directly read in the signals of the following components and transmit these via the steering wheel CAN to the steering column tube module control unit:
- Steering wheel downshift button (S110/1)
- Steering wheel upshift button (S111/1)
- Instrument cluster multifunction steering wheel button group (S163/1)
- Head unit multifunction steering wheel button group (S163/2)
AMG FlexRay
The signals are read in from the steering column tube module control unit via the AMG FlexRay.
Evaluation of input factors
The input factors that have been read in are evaluated by the integrated microprocessor and the relevant components are then actuated.
Actuation of components
Components are actuated with the following lines:
- Direct line
- Steering wheel CAN
Direct line
The following components are actuated directly via a looped line by the supplemental restraint system control unit (N210):
- Driver's airbag squib 1 (R12/13)
- Driver's airbag squib 2 (R12/14)
Steering wheel CAN
The steering wheel electronics directly actuates the multifunction steering wheel button groups (symbol lighting). The signals for this are received via the steering wheel CAN from the steering column tube module control unit.
Sending signals
The steering column tube module control unit sends, for example, the following signals via the chassis FlexRay:
- Status of steering wheel angle sensor
- Steering wheel angle
- Steering wheel velocity
- Combination switch, status
- Instrument cluster multifunction steering wheel button group status
- Head unit multifunction steering wheel button group status
- Status of steering wheel downshift button
- Status of steering wheel upshift button
- Status of steering column adjustment switch (with code P64 (Memory Package))
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.