What does fault code TCM-P086086 mean?

Diagnostic fault code details for TCM-P086086 (Volvo S60 (2011–), Volvo S80 (2007–), Volvo V40 (2013–)). Repair service at OBD Tuning.

VOLVO

TCM-P086086 - Gear Shift Control Module "A" Communication Circuit. Bus Signal / Message Failures. Signal invalid

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?

The signal from the gear selector control module (GSM) to the transmission control module (TCM) is invalid. The code is set when the signal is faulty, and the TCM then uses a default value instead of the selector's signal. The cause may be interference on the LIN wire or an internal fault in the selector control module.

Possible causes

Interference on the LIN wire linking the selector module (GSM) and the TCM
Internal fault in the selector control module (GSM)

What you can do

1Use a multimeter to check that the LIN wire is not shorted to ground or to plus.
2If you have a diagnostic tool: press the brake, move the selector to M and check that the status changes in live data.
3Check that the connector to the selector is secure and not corroded.
4Have a workshop disconnect the LIN wire to isolate the fault, as this needs workshop equipment.
5If no fault is found in the wire, have a workshop replace the gear selector control module (GSM).

Symptoms you may notice4

Message and warning symbol in the display
The gauges and gear indicator do not work
Manual gear changes are not possible
Low battery voltage warning

What the fault can affect1

The transmission control module (TCM) assumes a default value for the signal

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