Electronic unit and method for detecting a polarity inversion of the onboard power supply voltage in motor vehicles

An electronic unit for a motor vehicle having an onboard power supply, comprising:

• a connection for a negative onboard power supply voltage;
• a connection for a positive onboard power supply voltage;
• an internal electrical supply unit which can be used independently of the onboard power supply or its polarity;
• and
• a functional unit which compares actual voltage present at the connection for the negative onboard power supply voltage with a defined upper limit value, and detects and causes storage of data concerning a polarity inversion of the onboard power supply voltage if the actual voltage at the connection for the negative onboard power supply voltage is higher than the defined upper limit value.

An electronic unit in a motor vehicle having an onboard power supply, comprising:

• a connection for a negative onboard power supply voltage;
• a connection for a positive onboard power supply voltage;
• an internal electrical supply unit which can be used independently of the onboard power supply or its polarity;
• and
• a functional unit which compares actual voltage present at the connection for the positive onboard power supply voltage with a defined lower limit value, and detects and causes storage of data concerning a polarity inversion of the onboard power supply voltage if the actual voltage at the connection for the positive onboard power supply voltage is lower than the defined lower limit value.

A method of detecting a polarity inversion of onboard power supply voltages present at positive and negative input terminals of an electronic unit in a motor vehicle, comprising:

• detecting magnitude of voltages present at said positive and negative terminals of said electronic unit;
• comparing said detected voltages;
• and
• detecting a polarity inversion of the onboard power supply when voltage present at the negative input terminal is greater than voltage present at the positive terminal.

A method of detecting a polarity inversion of onboard power supply voltages present at positive and negative input terminals of an electronic unit in a motor vehicle, comprising:

• detecting magnitude of voltages present at said positive and negative terminals of said electronic unit;
• comparing voltage present at positive input terminal with a defined lower limit value;
• and
• detecting a polarity inversion of the onboard power supply when voltage present at the positive input terminal is lower than said defined lower limit value.

A method of protecting an electronic unit in a vehicle, said electronic unit having positive and negative electrical input terminals for connection to an on-board power supply of the vehicle, against a polarity inversion of the onboard power supply comprising:

• providing said electronic unit with an internal electric supply which is independent of the onboard power supply;
• measuring voltages present at at least one of said electrical input terminals;
• comparing measured voltages with a reference value;
• detecting a polarity inversion of said onboard power supply based on a result of said comparing;
• and
• said internal electric power supply providing electric power to operate said electronic unit in response to detection of a polarity inversion of said onboard power supply.

A method of operating an electronic unit in a vehicle having an onboard power supply, said electronic unit having terminals for receiving positive and negative voltages from said onboard power supply, and an internal electrical supply unit which can be actuated to supply power for operation of the electronic unit independently of said onboard power supply;

• said method comprising:
• comparing actual voltage present at at least one of said positive or negative voltage connections with a second voltage value;
• detecting occurrence of a polarity inversion of the onboard power supply based on a result of said comparison;
• during a detected polarity inversion, causing said internal electrical supply unit to supply power for operation of said electronic unit independently of said onboard power supply;
• and
• storing data characterizing said polarity inversion in a medium that is readable by a vehicle diagnostic unit.