Help with Wiring Diagram for 2013 Prius Head Unit

You may need both the Repair Manual (more info) and the Electrical Wiring Diagram. Versions of both are as close as your Phoenix Public Library card: visit this page, select 2013 Toyota Prius, and then click:

• Chassis Electrical > Audio/Visual/Telematics > Navigation / Multi Info Display > Navigation System (For Radio And Display Type) >
  • Terminals Of ECU (2013 Prius From 10/2012)
  • Speaker Circuit (2013 Prius From 10/2012)
  • AVC-LAN Circuit (2013 Prius From 10/2012)
  • Mute Signal Circuit Between Radio Receiver And Stereo Component Amplifier (2013 Prius From 10/2012)
  • Navigation Voice Circuit Between Radio Receiver And Stereo Component Amplifier (2013 Prius From 10/2012)
  • Radio Receiver Power Source Circuit (2013 Prius From 10/2012)
• Wiring Diagrams > System Circuits > Audio/Visual/Telematics >
  • Audio System (Separate Type Amplifier) or
  • Audio System (Built-In Type Amplifier)

More than slightly, I’m afraid. Model year 2013 Prius cars built for the U.S. market have one of four types of head units, depending on the grade (trim level) and option packages.

If your car originally had a 86140-47180 head unit, with an APPS button, a JBL logo, and ID number 57034 on the front, it’s the configuration with navigation that the Electrical Wiring Diagram describes as “Separate Type Amplifier” and “w/ Radio & Display Receiver Assembly Type.” The head unit has a 20-position connector (L138) for power, ground, and the wiring to the stereo component amplifier assembly under the right front seat, which drives eight speakers.

The 86140-47050 head unit, with a ▶︎‖ button, no JBL logo, and ID number 57031, was used on grades without navigation or a separate amplifier. This configuration is described in the Electrical Wiring Diagram as “Built-in Type Amplifier,” with six speakers wired directly to connector L146/L147 on the head unit. That’s the connector with wires sticking out of it in your photo above.

If you can’t get a head unit of the originally-installed type, changing between these two configurations would require some rewiring if you want the speakers to work—it’s not just a matter of re-pinning some connectors. You’d have to bypass the separate amplifier and extend the speaker wires up to the head unit, deciding which of the eight speakers to wire to the four output channels of the amplifier built into the head unit.