What does fault code TCM-P179997 mean?

Diagnostic fault code details for TCM-P179997 (Volvo S60 (2011–), Volvo S80 (2007–), Volvo V40 (2013–)). Repair service at OBD Tuning.

VOLVO

TCM-P179997 - CAN TCM/ABS Circuit Malfunction. Component Failures. Component or system operation obstructed or blocked

System

Transmission Control Module (TCM)

Volvo models this fault code applies to

Applies to the following models:

9 models

S60 (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)

What does this fault code mean?

Although the fault code is named component failure and blocked, it applies when the speed value from the brake controller (BCM) is absent or unreliable. The brake control module receives the speed from four wheel sensors and sends it over the CAN network to the transmission control module, which uses it to calculate shift timing. The fault is general and does not say more precisely what type of fault it is.

Possible causes

Fault in the brake control module (BCM), which should be diagnosed first
Sporadic open or shorted CAN wire between the brake control module and the TCM
Damaged wheel sensor
Internal fault inside the control module (TCM) of the gearbox

What you can do

1Read the fault codes in the CEM and the brake control module (BCM) and fix those first
2Clear this code only after the root fault has been fixed and its fault code cleared
3The brake system is safety critical, so do not work on it yourself. Have a workshop check the wheel sensors and the CAN lead

Symptoms you may notice5

Warning symbol and text message in the display
Gear changes too early, too late or too often
Gear changes take too long, or are harsh and jerky
No forward or reverse movement with a gear engaged
Engine stalls when a gear is engaged, and lockup does not work

General guidance for car owners. Diagnosis on the car can point to a different cause.