VOLVO
TCM-U003700 - Communication bus "B". General Failure Information. No sub type information
System
Transmission Control Module (TCM)
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–)
Show models by year and engine (9)
- Volvo S60 (2011–)2014–2015Transmission TG-81SC only
- Volvo S80 (2007–)2014–2015Transmission TG-81SC only
- Volvo V40 (2013–)2015Transmission TG-81SC only
- Volvo V40 Cross Country (2013–)2015Transmission TG-81SC, TG-81SC AWD only
- Volvo V60 (2011–)2014–2015Transmission TG-81SC only
- Volvo V60 Cross Country (2015–)2015Transmission TG-81SC only
- Volvo V70 (2008–)2014–2015Transmission TG-81SC only
- Volvo XC60 (2009–)2014–2015Transmission TG-81SC only
- Volvo XC70 (2008–)2014–2015Transmission TG-81SC only
What does this fault code mean?
The transmission control module (TCM) has detected a fault on communication bus B (HS-CAN 2). The code gives no specific fault type. Because bus B is not working correctly, gear shifting, the engine start-stop function and some gearbox adaptations can be affected.
Possible causes
- Contact resistance, corrosion or a loose connection in connectors or joints
- Short circuit between the CAN wires
- Open circuit in one of the CAN wires
- Internal fault in another control module on the same part of the CAN network
- The gearbox control module (TCM) itself is faulty
What you can do
- 1Read codes from the other control modules and deal with them first, as CAN faults often set several codes at once
- 2Check that the battery is charged and the terminals are tight
- 3Check visible connectors and wiring to the gearbox for looseness, corrosion and damage
- 4Have a workshop check which module is disturbing bus B, as this needs diagnostic equipment
- 5Clear the code only once the fault has been fixed and check that it does not return
Symptoms you may notice5
- Check engine lamp lit
- The engine may stall when a gear is selected or when braking
- The automatic gearbox does not shift automatically or manually, and kickdown does not work
- The gearbox shifts harshly or jerkily on upshifts and downshifts
- Automatic engine start-stop does not work
What the fault can affect3
- Gearbox adaptation is blocked
- Neutral control is blocked
- The automatic engine start-stop function is switched off
General guidance for car owners. Diagnosis on the car can point to a different cause.