Cruise control success

This weekend I've finally successfully added cruise control to my 2014 reg Prius C.
I thought I'd add my steps here to help anyone planning anything similar.

Steps:

1. Disconnect the negative terminal of the normal 12v battery and make sure it won't accidentally touch the terminal while you're working. Wait 90 seconds before continuing.
   If this is in the boot/trunk, consider blocking off the latch of the boot/trunk so you can close it without it locking. With the batter disconnected, you cannot open the boot/trunk again so you'll be forced to lower the rear seats and climb in that way. For some models, the 12v battery is accessible under the rear passenger seat, so this is less of an issue.
2. Pop the caps off from either side of the steering wheel.
3. Using a flat-head screwdriver, press inward on the steel pin, not where it curves, but where is goes straight down. Repeat for both sides of the steering wheel. The airbag will now pop out enough for you to work. Some people recommend removing the airbag cable, I was able to work without doing this.
4. Connect the cabling supplied to your cruise-control stalk, and connect the other side to the free port beside where the airbag cable is connected to.
5. For some cars, this seems to be enough. Reconnect everything remembering to press hard on all sides of the horn to secure the airbag in place, then reconnect the battery and see if it works. Press the button on the end of the stalk with the car on. Do you see the green cruise control icon on the dash? If not, continue reading.
6. Whether your car is North American, European, UK or Japanese, the ECU will be located on the left side of the car (from the driver's viewpoint). So, UK/Japanese it will be behind the glove box, and for others it will be below and to the right of the steering wheel. So remove the relevant covers with a good hard tug.
7. Also remove the lower plastic cover from under the steering wheel column (the piece that surrounds the steering wheel adjusting lever).
8. Under the steering wheel there's a port you'll need to remove. It's called G5.
   
   
9. As you can see from my G5, there's an unused port in the bottom left. You'll need to run a wire from this port to the appropriate port on the ECU. So connect a long enough wire to that port.
10. You'll also see from that picture that my car already has a white cable connected to the port next to it (in the bottom left, in one). That's the ground port. If you already have a wire in there, then there's no need to run another one. If it has no wire, then you'll need to run a wire from that port to any chassis-mounted bolt, securing it in.
    
11. Reconnect G5.
12. That wire you ran from the bottom left port on G5 now needs to be connected to the ECU. This can vary depending on your exact Prius model.
    
    For 2012-2014 Models:
13. Looking at the ECU, you'll see there are 4 grey ports. Remove the upper most one by squeezing then pulling. This is called G58.
    
    
14. Insert your wire into the port shown (pin 22). Squeeze it in well.
    
    
15. Reconnect G58.
16. Reconnect the battery and any trimmings you removed.
17. Start the engine and press the button on the end of your cruise-control stalk. You should see the green cruise-control icon on the dashboard.
    
    2015 Models
18. Instead of looking for G58, remove the 2nd from the top. This is G57.
    
    
19. Run your cruise-control cable into port 28. If you're looking from where the wires go in then it'll be on the bottom right side. If you're looking from the front view (as diagramed), it's on the bottom left.
    

I had a bit of fun and tried to drive quite efficiently today after installing it. I managed to get some very good MPG figures. 82.6MPG for a journey of over 30 miles.
I'm a happy camper!


Here is the guide I followed:
https://www.rostra.com/manuals/250-1836_Form5350B.pdf