Sony developed the MDX-5V101R for Volkswagen Japan as an OEM radio for the MKIV Passat/Jetta/Golf released in 1998-1999. As such it only supports SP tracks, MDLP is not supported.

The unit turns on and off by depressing the volume knob. Buttons not found on US radios and their function:

Ti = Traffic information, a special frequency used in Japan
SCRL = Begins scrolling of disk name or track text if they are too long to fit.
AS = Next disc, allows you to advance a CD/MD changer with more than 6 slots
DSPL = Switches between 3 modes for what info the faceplate should display.

1. Disk#; Disk Name; Total Tracks; Folder name(s) ▶
   
2. Track Name
3. Track #, Time Elapsed
   

REP = Toggles replay
SHUF = Begins cycling a 2 digit random number generator for a couple seconds before picking a track. Rumor has it if 666 ever comes up you die instantly, your soul claimed by Deezelbub.

Despite using the same ISO and mini-ISO connectors as radios for the US and EU markets, the 5V101R changes the pin assignments. It also defers by using the Sony Unilink protocol for communicating with dash and trunk mounted accessories, breaking compatibility. It has only one DATA pin for accessories where US and EU market radios have DATA IN and DATA OUT. The radio also has a GALA pin connection to raise and lower the volume with vehicle speed changes.

Because theft does not exist in Japan, the MDX-5V101R has no radio code security feature, making them plug and play. Unlike US and EU market radios.

Content adapted from: source

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