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.
Control Module
Trailer module (TRM) has the task of managing the electrical connections between the vehicle and trailer.
The main task of the control module is to manage output signals to the cable harness for the tow hitch for:
- Turn signal lamps
- Brake light
- Parking lamps
- Back-up lamp
- Fog lights
- Charging (+12 V voltage).
The Trailer module (TRM) also communicates via the CAN with:
- Central electronic module (CEM)
- Driver information module (DIM)
- the Differential electronic module (DEM) (option)
- Obstacle Detection Control Module left (SODL) (4/126) (For V40 (13-))
- Obstacle Detection Control Module right (SODR) (4/127) (For V40 (13-))
- Parking Assistance Camera (PAC) (option)
- the Parking Assistance Module (PAM) (option).
- Engine control module (ECM)
- Brake control module (BCM)
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.