Revved very high at constant 65mph, now won't go into gear. got BRT

So a few days ago my BRT came on while driving. It has done this before, and I figured the battery was probably unhappy from all the sitting it has done lately. I've been driving about twice a week versus daily. Typically when teh BRT rears its ugly head, over the course of five or so start-ups the various lights go off (braking, stability control, and then the BRT.) This time things got worse though.

I was driving on the highway and noticed that the battery fan had come on and it stayed on for about half an hour before the car suddenly revved up very high (like 5-6k rpm by ear) despite the fact that I was not giving it any more gas than required to maintain a steady 65 mph. Despite the high revs the car wasn't accelerating. I tapped the brakes and the engine slowed to a more normal speed, but giving it gas yielded less power than normal. I pulled off onto the shoulder and let the car run hoping to let the battery cool or recharge and we could resume. The display indicated the battery was half full.

After five or so minutes I tried to resume driving. The car had noticeably less power. I got off the highway and was able to get up to about 35 mph. I was not flooring it, but I definitely had to give it more throttle than I'd typically give it for the same performance. I parked it at an industrial park at which point I noticed the battery was now indicating one bar SOC. After about ten minutes of the engine running, which it had been doing the entire time, the SOC hadn't budged. I decided to park it, let the battery cool and return in a few hours.

Upon return I powered the car on and tried to limp it a few miles to a place that I could park it without fear of being towed. The car would not go into drive or reverse. As soon as I put the shifter to N it would say on the display that I needed to put the car into park to charge the battery. On the MFD it would show juice going to the battery for about one second, then it would stop for one or two seconds, then repeat.

I've owned this car for four years now. I've replaced a few modules in the pack twice. Both times I had one module that had voltage in the 6-7V range.

I yanked the battery last night and brought it home. Upon pulling off the vent tubes I smelled ozone. Only one module tested excessively low. In the past this has not prevented movement, but I've also never smelled ozone. Would a dead pack prevent the car from going into gear?

Another nugget is that the display has gone dark before suggesting the combination meter is ailing. It's only done it about five times over the last three or so years and was always lit yesterday through the entire ordeal. I only mention this since this since I'd found a post that claimed that a bad CM would prevent the car from going into gear. However, I'd found another one that says you can drive with no CM at all. So I am not sold on the concept and it seems to me the battery is the more likely cause. Having a bad CM would not cause the battery fan to run.

I am hoping that what happened is that the bad module was getting hot, which caused the fan to come on. Eventually the voltage dipped low enough that the car decided the battery pack could not be used. It then reverted to only using the engine, which provides sluggish performance. Once I turned the car off and let the gasoline engine stop running the car knows it doesn't have the ability to restart the engine since the battery is kapoot, so it won't even allow the car to go into gear since it can't move the car by electric motor alone and can't start the engine without the electric motor. Any merit to that theory?

I'm currently asking because I'd like to replace about 7 weak cells (they're about .05-.08V lower than the rest, but not super-low) but I don't want to throw $250 at the car if it is more likely to be a transmission or inverter or something much more expensive that might make me replace the entire car.

Any wisdom is appreciated.

Have a good one,
Bill

 

Just noticed that in creating the original post I put a sentence in the wrong paragraph. The bit about the MFD indicating that the battery would charge intermittently was happening earlier when the engine was still running and the car was charging. It was not after I had shut the car down and returned.

 

The car has about 155K miles. The battery was replaced by the last owner in 2015 with a hodge podge of modules that have date codes ranging from 2003 to 2012.

I know the battery is shot. I guess the wisdom I am looking for is whether or not that is what is causing the car to not go into gear. Is it simply the battery, or is it likely to be something else? Any idea about that? Is the theory I outlined toward the end of the original post valid?

 

I got some modules and swapped out all the suspect modules and put the pack back in. I reconnected the 12V, crossed my fingers, and no luck.

The car will not go into gear at all and does not have a ready light. I know the brake sensor is working because it only takes one push of Power button to turn to on. I am not getting the clicks from the back of the car when I turn the car on. When I check voltage on the output side of the contactors I get zero despite having 218 before the contactors.

So what prevents the contractor from closing?

I have a jump pack and hooked that up to the battery. That got me from where shifting to neutral would instantly result in a message to shift back to park to no message. So a slight improvement, but it still won't shift into D or R.

Any ideas?

 

Thank you everyone for your input.

So after my last post I snooped around and this is what I found:

-No amount of disconnecting and reconnecting the 12V for any amount of time has changed anything.
-Pressing the power button for 45 seconds didn't seem to reset anything.
-The contactors were not shutting, so even though I had 218V going into them, I had nothing coming out.
-The white, yellow and black wires feeding the two contactors and the relay that activates the precharge circuit were all getting voltage when I hit the Power button. I surmised this by unplugging that connector and checking each supply wire to ground. I used the ground that they use so I could eliminate bad grounds. I'd get an initial hit in the 12.X V range, then it would very quickly drop to somewhere in the 11.X V range. So I suspected that the 12V battery is low. I checked continuity from that ground to the 12V battery, and it is good. I took the 12V battery to Advance Auto and they tested it and said it is good but low on charge and offered to charge it. I accepted and am going to pick it up today and try putting it in.

So I am pretty sure that the current reason that the contactors and precharge relay are not activating despite having juice is that the 12V is not strong enough to activate them.

So here is my overall theory of what happened. I had a bad traction battery, which caused the cooling fan to run constantly. Eventually the battery got bad enough that the car opened the contactors. PERHAPS upon doing so the MGs stopped sending juice to even the 12V so the car ran off the 12V, which depleted it far enough that when I then went back a few hours later and tried to restart it it couldn't produce enough current to close the contactors. Just a theory.

So my plan is to put the 12V in and hope for the best. I am also going to bring a spare 12V battery and only use that as a 'jump battery' if the Prius 12V doesn't work to prevent running down the freshly charged battery in the course of troubleshooting. I realize it may have some fatal fault codes that need to be cleared before it will run. Ed seemed to suggest that disconnecting the 12V will temporarily clear the fatal codes. I am not sure I understand that fully. Does that mean that they will be cleared for a few seconds after reconnecting the battery and if I were to try the car within that window of time it might work, but after a few seconds it will not? If that is what is meant, then how long do I have? Should I bring another person so I can reconnect it and have them press the button immediately, or do I have ten seconds to get there? My impression from elsewhere on the site is that only the dealer can clear those codes. My neighbor has a fairly nice, but not Prius-specific code reader, which I plan to take with me today. I'm assuming that the Prius-specific ones people allude to on this site are not available in brick and mortar stores. Perhaps I should get one regardless. I had a first gen Insight before this and those you could read blink codes just by shorting two pins on the OBDII and turning on the key. Made life much easier.

Any comments on my theory?
Any wisdom on how to reset fatal codes other than Ed's suggestion?

Have a good one,
Bill

 

I put the freshly charged 12V battery in. It was reading 13.01V before installing. I powered the car up, but it still will not go into gear and the contactors are not clicking. The voltage at the jump terminal is 12.72. although the nut on the strut tower that I use for ground there is pretty corroded. So there might be more potential at the jump post than that number suggests.

I tried my neighbor's code reader, which they had described as "very nice." It is a FIXD brand and uses Bluetooth to talk to a phone. It found zero errors even though the CEL persists. I guess the only errors still in the computer are toyota-specific codes that it doesn't recognize.

Anything else to try before I tow this to a dealer?

 

We have a winner! I have read it several times, and replaced my 12 V because of it. However today I see the true power of the advice that even a seemingly good 12V can be bad enough to cause problems. Even after a fresh charge it couldn't shut the contactors. So just for giggles I wired my spare 12V from another car in parallel with it. Despite the fact the second battery was only reading 12.48V it was able to shut the contactors and the car started the IC engine and went into gear. So going to go get a new battery.

Hopefully this will help others, and hopefully this entire ordeal is over. Thank you everyone for advice, which mostly seemed to revolve around assessment of the health of the 12V. You were on the right track.

 

I agree that checking the OBDII codes first would have been a smart way to go. I was hoping that disconnecting the 12 V would reset something and cause the car to work. No dice on that though.

I definitely need to get a decent reader and app. That is on my list of stuff to research in the next few days. Lately I've been catching up on all the stuff I should have been doing while I was driving out to where the car was stranded and working on it. I was using a FIXD, which showed me no codes, but I'd disconnected the 12V several times by the time I borrowed that reader and used it.

So after figuring out that the spare battery I had could close the contactors fine with 12.48V, but the yellowtop in the car couldn't do it with 12.7V, I suspected something amiss with that battery, but couldn't find anything. But totally by chance as I was disconnecting the terminals I noticed that the negative post moved. Upon closer inspection I found a crack in the post that went about 3/4 of the way around. The post was hollow, which I never would have suspected. So I am sure that was creating a high resistance spot, which would cause the voltage to drop when the current goes up. I assume the crack was from over-torquing the terminals. So don't overtorque your battery terminals!