GENERAL DESCRIPTION of P1693
The immobilizer system includes PCM / ECM and SMARTRA3 units, as well as ignition keys with a built-in transponder.
PCM / ECM checks the ignition key using a special encryption algorithm using SMARTRA3 and a transponder.
The encryption algorithm (between PCM / ECM and SMARTRA3) was developed by BOSCH.
The encryption algorithm (between PCM / ECM and transponder) is of type Hitag 2, which is used by high-level systems. When the ignition is on, the PCM / ECM performs SMARTRA3 authentication, then the key authentication. The engine can be started after confirming the authentication of the key from the SMARTRA3.
The key programming procedure is initiated by the PCM / ECM with a PIN code request from the scanner. A “clean” PCM / ECM unit saves the PIN, then proceeds to register the keys. The registered PCM / ECM compares the PIN code received from the scanner with the vehicle password recorded in the transponder. If the data is correct, the key registration procedure starts.
The scanner asks for permission to register the first key, after which the PCM / ECM first registers the SMARTRA3, and then the first key. If the SMARTRA3 is already registered and the PIN is different, the SMARTRA3 returns the wrong PIN to the PCM / ECM. In this case, PCM / ECM cannot register keys.
DESCRIPTION OF DIAGNOSTIC TROUBLE CODE
In case of an incorrect response from the transponder, the PCM / ECM unit registers the code P1693.