Fault-Tracing Information

Fault-tracing information

Condition




The signal for the input speed comes from a sensor inside the transmission control system. The transmission control module (TCM) bases its calculation of the speed of the input shaft after the torque converter on this signal. The signal is used to compare the speed of the gearbox with the vehicle speed. Using this comparison, the control module can calculate the gear shifting points.
The information on RPM and speed affects the adjustment of the system pressure (control of the lock-up function) and the reduction of the engine torque when changing gear. This results in smoother gear changes.
The information is used also for controlling the lock-up function. The transmission control module (TCM) calculates and compares also the gearbox input speed and output speed plus the engine speed for diagnosis.
If the transmission control module (TCM) registers that the signal from the speed sensor is missing, the diagnostic trouble code (DTC) will be generated.
The diagnostic trouble code (DTC) can be diagnosed at speeds above approximately 70 km/h and when the temperature of the transmission fluid exceeds 20 °C.

Substitute value
- Auxiliary program Emergency mode 1 in the transmission control module (TCM) has started.

Hint: Emergency mode in case of malfunction Emergency Mode In Case of Malfunction

Possible source
- Contact resistance in the terminals
- Gearbox input speed sensor not working.
- Internal fault in transmission control module (TCM).

Fault symptom[s]
- Malfunction indicator lamp (MIL) lit.
- General warning lamp lit
- No lock-up function.
- Harsh gear changing
- No gear changing.