Unfortunately, the microphone is pre-amplified with what I believe to be a New Japan Radio Co. 2140 Op-Amp (the black IC in the middle on front side, pin 1 is upper left corner).
Front side
Back side
When connected to the factory head unit, the output signal of the factory microphone module was about 500mv peak-to-peak and centered on 0.0v.
Factory microphone output signal when connected to factory head unit
I wasn’t able to get a great oscilloscope capture of the factory microphone output when connected to the Sony head unit, but it ended up being biased by about 3.3v and about 400mv peak-to-peak.
I could have re-wired the factory microphone circuit to remove the amplification, or even made a new circuit to de-amplify it and put that inline. But I decided that was too much work and just installed an external 3.5mm microphone instead:
Note: The 2010 Prius did not include a USB adapter/plug — even for the Trim V and/or Nav package
Note: For the 2010 Prius you’ll need the one that is 22mm x 33mm (0.87in x 1.3in). This is also the same size as the 2015 RAV4.
Steering Wheel Control
I originally thought I needed the ASWC-1, but as it turns out there’s two ways Steering Wheel Control (SWC) signals could be sent: either as voltage-based1 analog or as digital signals over the CANBUS.
Fortunately for me, both my Prius and the Sony XAV-AX100 use the voltage-based analog SWC signaling. I lopped off the black connector of the Metra 70-8114 (which normally would plug into the ASWC-1) and soldered to the red/white wires of the 3.5mm connector:
Green/Orange to thin White (SW1)
Green/Black to thin Red (SW2)
Terminal
Condition
Specification*
L41-7 (SW1)
Seek+ switch pushed
< 0.8 V
L41-7 (SW1)
Seek- switch pushed
0.9 to 1.3 V
L41-7 (SW1)
Volume+ switch pushed
1.65 to 1.9 V
L41-7 (SW1)
Volume- switch pushed
2.45 to 2.6 V
L41-7 (SW1)
Steering pad switch not operated
3.28 to 3.5 V
L41-8 (SW2)
MODE switch pushed
< 0.8 V
L41-8 (SW2)
On hook switch pushed
0.9 to 1.3 V
L41-8 (SW2)
Off hook switch pushed
1.65 to 1.9 V
L41-8 (SW2)
Voice switch pushed
2.45 to 2.6 V
L41-8 (SW2)
Steering pad switch not operated
3.28 to 3.5 V
* With respect to L40-20 (GND)
On the XAV-AX100, there’s an option to program the SWC buttons, so I did that and everything works as expected.
Microphone
The Prius has a microphone (at least mine does) and I wanted to keep that microphone instead of adding a new one.
The microphone in the Prius requires 5V for it’s built in amp, which looks like is always powered when the car is on.
DC/DC Converter 5V to Prius L37-17 (MACC, Telephone microphone assembly power supply, 5V)
Sony XAV-AX100 Black to Prius L37-18(SGND, Shield ground)
Sony XAV-AX100 Mic Tip to Prius L37-19(MIN+, Microphone voice signal)
Sony XAV-AX100 Mic Sleeve to Prius L37-20(MIN-, Microphone voice signal)
Note: I think this works…though I’m having some call quality issues. Not sure if it’s related to this, CarPlay, or something else.
Assumes factory backup camera, remember to plug the Yellow RCA cable into the Radio as well.
You can buy the L42 connector with a pigtail from https://autoharnesshouse.com/49914.html, or just do what I did and stick a wire in the female connector and tape it .
Normal (only on when in reverse)
AX-CAM6 Blue/White(Reverse trigger) to Sony XAV-AX100 Purple/white (Reverse In) and to Prius L42-5 (Reverse Signal)
AX-CAM6 Black(Ground) to Sony XAV-AX100 Black (Ground)
AX-CAM6 Blue/Red (Camera power, 6V) to Prius L37-24(CA+, Television camera power supply, 5.5 to 7V)
Always available
AX-CAM6 Blue/White(Reverse trigger) to Sony XAV-AX100 Red (Accessory Power, 12V)
AX-CAM6 Black(Ground) to Sony XAV-AX100 Black (Ground)
AX-CAM6 Blue/Red (Camera power, 6V) to Prius L37-24(CA+, Television camera power supply, 5.5 to 7V)
Prius L42-5 (Reverse Signal) to Sony XAV-AX100 Purple/white (Reverse In)
Other Notes:
The color and texture of the dash kit definitely does not match, but I’m not sure there is one that does.
It’s been a while since I’ve replaced a factory radio, and this one took me some time to figure out the SWC, microphone, and backup camera. I was used to the Old Days™ where the radio comes with a pigtail connector, you buy a pigtail connector for your vehicle, solder the two together and that’s it.
I installed the Dual port USB adapter, but only the USB connector for the audio is currently hooked up. I still need to hook up the second USB for charging. My current plan is to run the wire to the 12V cigarette adapter in the center console.
There’s an adjustment for the volume on the Metra TYTO-01, I think I set mine too low because A) I have the radio cranked up pretty high when driving (the Prius is notorious for road noise), and B) when I’m playing Spotify through CarPlay it sounds like the audio is clipping. So I’ll need to take the dash apart again and adjust that.
While I did remember to remove all the music CD’s from the factory radio before I uninstalled it, I forgot to clear the Oil Maintenance reminder message (which is set and controlled through the factory radio)…so I’ll probably need to hook it back up to clear it *facepalm*
