Diagnostic trouble code (DTC) information

Condition

Fig 1: Identifying Control Module

Courtesy of VOLVO CARS OF NORTH AMERICA.

The solenoids are controlled by power stages in the transmission control module (TCM). The transmission control module (TCM) opens the power stages to activate the solenoids and sends a voltage through the circuit. Diagnostic trouble code (DTC) TCM-0120, TCM-0121, TCM-0122, TCM-0123 or TCM-0124 is stored (depending on the power stage) if the transmission control module (TCM) registers an internal fault in the power stage circuit for solenoids S1, S2, S3, S4, S5, SLU, SLT or SLS.

Substitute Value

Transmission control module (TCM) "Limp Home" program initiated.

Possible Source

Internal fault in the control module.

Fault symptom[s]

The warning lamp for the automatic transmission flashes
Malfunction indicator lamp (MIL) lit
No lock-up function
Harsh gear shifting
No shifting.

Harsh gear shifting can be caused by:

No reduction of the line pressure when shifting
No request for torque limiting to the engine control module (ECM) when shifting.

HINT: No shifting because the transmission control module (TCM) prevents activation of the solenoids.