Disconnect the negative(-) battery terminal.
Disconnect the multi media jack connector after removing the under cover.
To inspect USB / iPod port, check the voltage between NO.1 and 4 terminal of.
Standard value : 5V
To inspect AUX jack, check the voltage between NO. 3 and 7 terminal of AUX jack / Audio jack input.
Standard value : 5V
Using an ohmmeter, check for continuity between the terminals of multi media jack connector.