Diagnostic Trouble Code (DTC) Information TCM-0020
Condition
The transmission speed sensor sends a signal to the transmission control module (TCM) about the engine speed (RPM) at the outgoing drive shaft. Using this signal, the control module calculates the output speed. The signal is compared with the signal from the transmission speed sensor (input speed) and is used to calculate the gear ratio of the transmission and for diagnostics.
The diagnostic trouble code (DTC) is stored if the transmission control module (TCM) registers that the speed signal from the brake control module (BCM) does not correspond to the signal from the transmission speed sensor.
The diagnostic trouble code (DTC) can be diagnosed at speeds above approximately 30 km/h and when the engine speed (RPM) is above 400 rpm.
Substitute Value
- Blocking adaptation
- Blocking lock-up
- Blocking slipping lock-up
- Blocking of neutral check
- If the speed signal from the brake control module (BCM) is missing, the emergency program Emergency mode 1 in the transmission control module (TCM) is initiated
- The transmission control module (TCM) uses the speed signal that the brake control module (BCM) puts out on the control area network (CAN).
HINT: EMERGENCY MODE IN THE EVENT OF A FAULT
Possible Source
- Contact resistance in the terminals
- The transmission speed sensor is loose
- The transmission speed sensor does not function
- The wheel radius does not correspond to the programmed wheel radius in the transmission control module (TCM).
Fault symptom[s]
- Malfunction indicator lamp (MIL) lit
- General warning lamp lit
- No lock-up function
- Harsh gear shifting
- No shifting.