The radio frequency locking system with integrated immobilizer (RFL) has a diagnostic capability only in the case of the CAN version. Diagnosis with the HHT is possible only on vehicles fitted with engine 601/602.
PWM version (models with engine 111)
No diagnosis is possible with the HHT. It is possible, however, to use the HHT to read the status of the immobilizer (activated/deactivated) by means of the actual values of the PEC control module. See Diagnosis Manual Sprinter Chapter 11.1 operational check using actual values with the HHT (testing immobilizer).
CAN version (models with engine 601/602)
Diagnosis is performed through the CAN bus. The engine control module DSV or DFI is used in this case as a data transmitter between the radio frequency locking control module and the HHT connected to the 14-pin diagnostic socket.
Note
The DSV or DFI and RFL control modules fitted to the vehicle are interlocked to each other by means of an identification. For this reason, a malfunction in one of the systems may in certain circumstances affect both control modules. For this reason, take into account both systems when carrying out troubleshooting.
See Diagnosis Manual Sprinter Chapter 12.
Not all control module functions are activated in the diagnostic mode. It is not possible, for example, to unlock or to lock the vehicle with the transmitter key.
In certain circumstances, the immobilizer indicator lamp in the instrument cluster may come on during or after performing diagnosis. This should be reset by activating and deactivating the immobilizer in the proper way with the transmitter key.