I have a question for the author of the post, did it solve the problem?
On the table I have just such a module and the case looks like that the microcontroller sends pulses lasting 15ms with interruptions lasting 100ms. These pulses are on pin 27 (power down) of the TDA5210 radio receiver system. It looks like the radio system was started at short intervals in to minimize power consumption, although in the active state this current is still small (7mA). I only add that the FM / AM radio amplifier takes 100mA. The car owner provided me only the module without the key so I can not check much, it seems strange to connect the pin 27 tda5210 to mcu, if it was to be in high condition all the time. In the module that fix the corroded only power cord tracks (12v), I sold them and gave the module to the owner. However, he came back to me and from what the module says the module still does not work. On pin 2 of the power socket I have 0V and the author of the post is 4.7V. Is it a data output (after processing) of the pro cesora?