LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Volvo >> 2004 >> XC90 Base, AWD >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Transmission Control Module (TCM) Diagnostic Trouble Codes - 7 Of 9 >> TCM-P086087: Transmission Control Module A Communication Circuit. Bus/Message Error. Message Missing (B8444S, TF-80SC AWD; 2006-2011) >> Fault Tracing TCM-P086087 >> Checking The Components And Wiring
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Checking The Components And Wiring

Check connector (16 pin) for the transmission control module (TCM) and gear selector module (GSM). Check for contact resistance and oxidation.

Check the communication cable (LIN) between the transmission control module (TCM) terminal #A7 and gear selector module (GSM) terminal #2. Check for an open-circuit.

Check the voltage supply cable between the transmission control module (TCM) terminal #A16 and the gear selector model (GSM) terminal #1. Check for an open circuit.

HINT: The gear selector module (GSM) is supplied with power by the transmission control module (TCM). 

Check the ground cable between the gear selector module (GSM) terminal #6 and ground. Check for an open circuit. Check the ground terminal for the ground cable.

If no fault can be found in the cable and the fault remains try replacing the printed circuit board (gear selector module (GSM).

Other information 

Fig 1: Transmission Control Module Connector Terminal Identification
GLL142131Courtesy of VOLVO CARS CORPORATION
Fig 2: Identifying Automatic Transmission Gear Shifter With Manual Gear Changer
GLL149370Courtesy of VOLVO CARS CORPORATION