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.
Signals, Brake Control Module (BCM) With Or Without STC (Stability And Traction Control) / TRACS (Traction Control System)
The table below summarizes the input signals to and output signals from the brake control module (BCM). The signal types are divided into directly connected signals, serial communication and Controller area network (CAN) communication. The following illustration displays the same information with the Volvo component designations.
| Input signals | Output signals |
| Directly connected: | Directly connected: |
| Four Wheel sensors
(7/31, 7/32, 7/56, 7/57) Pedal position sensor (7/124) |
|
| Via Controller Area Network (CAN) communication: | Via Controller Area Network (CAN) communication: |
| Central electronic module (CEM)
(4/56). Provides information about the car configuration. Transmission control module (TCM) (4/28). Provides information about the current gear, next gear and lock-up status (automatic transmission only). Climate control module (CCM) (3/112). Provides information that the driver has switched of the STC (Stability and traction control) function. Engine control module (ECM) (4/46):
Differential electronic module (DEM) (4/82). Provides information about the torque distribution to the rear wheels and the function status (All-wheel drive (AWD) only). |
Driver information module (DIM)
(5/1):
Climate control module (CCM) (3/112). Receives a request to light/turn off the indicator in the STC button. Transmission control module (TCM) (4/28):
Engine control module (ECM) (4/46):
Differential electronic module (DEM) (4/82). Receives information about the brake function (AWD). Road Traffic Information Module (RTI) (16/45). Receives information about the rotation speed of the front wheels. Used to measure distance. Phone Module (PHM) (16/60). Receives information about the traveled distance, used when the Global Positioning System makes calculations. |
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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.
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