Driving vehicle and it quit

So if I understand you're using your pickup truck as a voltmeter. You might want to let the dealer take a peek at it.

 

Check fuse AM2, if its blown your inverter coolant circulation pump is likely in need of replacement.

 

You have more than 3 gals of gas in the tank?

13.8 V on the battery posts while the car is READY (and NOT jumped to another vehicle) would indicate your 12V battery is receiving a low charge and that the DC-DC converter is doing its job. What is it with car off for 2 hours or more?

After checking the AM2 fuse, check the inverter reservoir for circulation.

Report back your findings.

 

Its unfortunate that many believe the diagnostic mode, on the MFD, provides useful information. Only if you are having radio/navigation issues, are those codes meaningful, or need to recalibrate the screen. The 12V battery health check is only slightly useful; easier to get out a DVM and check with greater accuracy. Besides a DVM is a very useful tool for the car and home.

Get the cheapest mini VCI from Amazon/eBay ($25). Software version doesn't really matter, as you can find a more current version online somewhere if you plan to work on very late model Toyotas/Lexus/Scions.

Read this for more information on setting up Techstream and using the min VCI cable.
TundraTalk.net - Toyota Tundra Discussion Forum - View Single Post - Offical TechStream software thread( settings and such)

Whatever laptop you install this hacked copy of Techstream on, this should be a spare junker laptop to be only used for Toyota diagnosis. Assume the software has malware on it tracking all your keystrokes and reporting to some criminal organization trying to steal your identity/financial information; definitely do not use this laptop on websites that require log-in/password entries (email, banking, etc). Given this warning, the many Prius gurus here have had no problems/issues using the hacked Techstream software. Two reason why you need mini VCI w/ Techstream is to read all the Prius specific codes that generic code readers miss and to bleed the brakes. Bleeding can be done w/o Techstream, but why experience misery?

Get the official Toyota service/repair manuals (engine, mechanical, interior, exterior, electrical, essentially EVERYTHING), go to TIS
Two days will cost you $15. Supposedly only business days are counted (remember reading this in other threads). If you start on a Friday 12:00:00 AM, you have until Monday 11:59:59 PM, to finish.

Supposedly PDFs no longer available from TIS. Another Prius Chat member discovered how to make a CHM file into a PDF. Toyota TIS download tips | PriusChat
This user downloaded both his Toyota cars over the course of his 2 business day subscription.
Internet search "CHM to PDF." There appears to be all kinds of software (some free, some purchase) that will accomplish this. Be weary of free as it could contain malware.