Prius starts with red triangle, stuck in Nuetral, no Drive or Reverse

The first thing to do is read the codes (or have the codes read) to find out why you have the Master Warning Light on.

If you get no codes, all that means is the reader used was inadequate and cannot read the hybrid system ECUs.

Report back with what codes your car has.

This thread has a review of some reader apps.

 

You need to read the codes as dolj said. Ideally, you should get an OBD2 reader to connect to your phone / tablet, to be able to read other troubleshooting data (battery voltages and more);

Many things could cause your symptoms. It sounds identical to when my battery ECU high voltage sense connector began draining some of the battery - it was made worse by leaving the car unused for a few days, and by damp weather…

However that is just one possibility - getting an OBD2 reader is good advice, as you can then get advice on these forums (many workshops may just say ‘you need a new hybrid battery’, when actually you don’t)…

 

Sounds like you're having the battery isolation fault issue You want to measure from one of the silver plugs on the orange safety plug with a DC voltmeter to one of the bolts that holds the battery to the floor or frame of the car when you touch the two leads to the proper places you should see DC voltage and it should count down to zero It probably will not it'll stop around 60 48 101 something like that and then sit there That's your problem that needs to count down to zero and it's not because the battery is not isolated from the chassis of the car and it's pushing voltage from your DC battery to your 12 volt grounding point for all your computers and 12 volt equipment and it's wreaking havoc on that use your cheap code scanner and clear the codes twice in a row without moving from the seat did the red triangle go away and now the car readys? Almost guaranteed your problem is the isolation fault now if you want and you want to go further find the code scanner that really can read the codes and doesn't have to clear it twice and you'll see the proper code I don't remember the number right offhand but it's a doozy The test with the voltmeter is called the down and dirty test for HD battery leakage there is a YouTube video showing you how to make the connections I use clamps so I don't have to hold the leads on the bolt heads I clamp them there and then stand there and watch the meter take a picture of it when it doesn't zero and fix it or tell the customer stand around like the monkeys and the Amoco commercial whatever The point is you found your problem I do think but it can be other things too don't get me wrong this is just a real common one and a generation two with some age on it

 

Here's the deal with a P0AA6. The HV cabling and system is insulated from the regular 12v system of the car. The HV system continuously monitors this 'separation' of the 2 systems and can be seen on techstream software as "shortwave highest value". When the separation is perfect, it shows a value of 5v on the Techstream software. When less than perfect, it shows a lower value. The worse it is, the lower the value, all the way to 0v. Around 3.2v, the car will trigger a P0AA6 code. If you are currently driving the car, the code will still allow you to drive, but as soon as you turn the car off, it will lock out the ability to go to ready/drive. If you reset the codes, it will allow you to drive the car again, and repeat the cycle. Without a good code reader/scanner, the easiest way to reset codes is to unplug the 12v battery.

Here's what just happened to me, after the same Debbie weather in South Carolina. It was a crazy day yesterday.

So a friend that I helped, months ago, calls me up and says his car coded as he was leaving the driveway. Sends me a dash photo. He describes all the symptoms of a P0AA6 fault. I drive 30 minutes to help, get there and my darn laptop won't fully start the Techstream program. Keeps asking for a new key code. Spend 30 minutes trying to get it working, even with the key code, but no luck. I'll need to come back after sorting out the laptop.

My son calls me. He's using my 2007 Touring. Car coded on the way to work, only a minute from his house. He sends me a picture of his dash while at a red light and continued to work 5 minutes down the road. Picture looks identical to the one from my friend, but pictures don't always tell the tale since many faults cause the same lights. 2 hours later, I finally figure out what's wrong with the laptop. It went to a default date of June 2008 and messed with the software subscription date. Got that working again and drove 30 minutes to check out the kid's car. P0AA6, 526/612. Everything looked good on techstream. Reset the codes. Shortwave was 4.99, hmmmm.. Told him to bring it to the house after work and we'd swap it with the 2006 so I'd have time to investigate further. I go home to get the 2006 ready.

Start the 2006 and plan to move it where I can wash it. 10 seconds later, RTOD. Park it. Dash looks identical to the two photos I've received. Knowing what's about to happen, I turn the car off and back on. Will not go ready, although READY flashed several times. Connect the laptop and find P0AA6, 526/612 and shortwave is 1.76v. Curious about the rash of P0AA6 codes after this weather, I pop the trunk and pull out the floor pieces. First thing I notice is the 12v battery is covered in condensation on every visible surface, including the terminal clamps. That's enough for me, most likely the HV battery is the same way. I unplugged the 12v battery to reset all the codes and then started the car. It coded again shortly after starting, but since it was READY, it allowed me to drive. Driving with the laptop/teschstream on line, the shortwave value increased to 4.2ish over about 5 miles. Stopped at a Wendy's parking lot and reset all the codes again. Then over the next 25 miles, shortwave improved to 4.99 with the occasional flicker to 4.97v. Took the car home.

Son gets to the house around 11pm. Says the car was driving perfect. Connected techstream again and shortwave was still 4.99. Hung out for a bit and a bite. I made sure he knew how to disconnect the 12v battery to reset codes just in case and then he headed back home with the 2007.

If this happened to me, on 3 different Gen 2 cars, I'd imaging it's going to happen to a LOT of gen 2s. The rapid change in temperatures and the huge amount of humidity is causing a lot of condensation. The car likely just needs to be started and run for a bit so the HV battery cooling fan can blow some air through the battery to dry the condensation.

 

Interesting. I wonder, do the apps that can command the battery fan ON also work with the car IG-ON, before you try to go READY? Maybe give it a few minutes to dry off before putting it to the test.

* wonders if it's worth getting one of those apps

 

This was actually in my plan, but.....my hybrid assistant app is on a dedicated Galaxy S3 I've had for quite a while. It hasn't been plugged in for a while and battery was dead. And...it's so dead it won't even charge. One more thing to add to my list from yesterday's day of hell...

 

After Debbie here in North Carolina Central part of the state Orange county both of the generation 3s are like terrariums The windows are rolled up they are sealed but seats are starting to show white mold where the high moisture content is and you can smell it the minute you open the door the persona turning the same way I have to get those moisture removal bags and hang them up in these things and they will dry out The generation 2's on the other hand are in seemingly stellar shape I just looked in the trunks today All of the generation twos had water in their 12 volt battery wells when I bought them that's been dealt with and the process to deal with it has shown to hold up well no water in the trunk no moisture in the back no droplets no condensation nothing in the generation twos of course they're driven The threes are sitting but they're not in total shade so they see the sun and all that until the rain came like this they were not like that on the inside. Even the two generation twos on site that are parts vehicles are completely dry inside quite surprised and one of those doesn't have tail lights in it or any of that but all the glass is intact completely dry inside one of my cats sleeps in it.