2011 Prius Radio Volume very low

The 2011 sales brochure says the Prius Two has a six-speaker system. This does not use a separate amplifier, according to the Repair Manual and Electrical Wiring Diagram, available by subscription to techinfo.toyota.com and in the ChiltonLibrary service, to which many public libraries sponsor access for their patrons.

You might be able to confirm the features on your car by entering the VIN in Toyota’s Vehicle Specification page; I don’t know if their database covers cars originally sold by Toyota de Puerto Rico, though.

I’d start with the Problem Symptoms Table in the Audio and Visual System section of the Repair Manual.

For the symptom “Sound quality is bad in all modes. (Volume is too low.),” with the six-speaker system, the manual says to check the “BASS,” “MID,” and “TREB” settings first, and then to check the speaker circuit, according to a detailed procedure. If there is no fault in the speakers, wire harnesses, or connectors, then the trouble is probably in the radio receiver assembly (head unit), for which no further diagnosis or internal repair instructions are provided.

That approach made sense when the radio receiver assembly was a $1,500 part, but now that they are available inexpensively from eBay sellers, if it were my car, I’d buy a spare, to avoid the need to disassemble the instrument panel more than once. After removing the head unit, I’d do the resistance checks at the L34 and L35 connectors, but I wouldn’t do any of the other speaker circuit checks, like those that require disconnecting the speakers from the wire harness, before trying the replacement head unit.

Parts catalog references:

• Figure 86-01, Radio Receiver & Amplifier & Condenser
• Figure 86-02, Speaker

 

I know this is probably not your issue, but figured I would toss this idea out there.

If you are listening to anything other than XM, FM or AM on your radio, the volume setting on your phone is all important.

When listening to a music file on your phone, or Pandora through the head unit controls (for example) the car’s volume controls will still work, but only up to the maximum volume you set on your phone.

I expect you are aware of this but sometimes one can overlook the super simple explanations.