Hymotion Prius won't start after charging but 12v battery okay

I've been driving a 2007 Prius with Hymotion installed for about 7,000 miles now. So far, the only issue I've had is the known issue where the 12v battery sometimes discharges when the Hymotion charges too long. Whenever this happens, I've always been able to fix it by jumping the battery.

A couple days ago, I went to start it, but it would not start after hitting the power button. This was after it was plugged in and charging overnight. I tried jumping, but still could not start. The interior lights worked and the key symbol on the dashboard was on. There were no error symbols. The usualy display with "Ready" never appeared.

I have two Priuses. I kept thinking that this had to be the 12 volt battery. So I took the 12 volt battery from my Hymotion Prius and moved it to my regular Prius. That one started up just fine. Then I took the 12 volt battery from the regular Prius and put it in the plug-in. When plugging it in the panic alert sounded, so I was hopeful something happened. However, when I pressed the power button, the same result happened......the interior lights worked, headlights worked, key symbol displayed on the dash....even the brake lights on the back.

The way it is acting almost leads me to believe that for some reason it thinks that it's still plugged in and charging. I know Hymotion disables the power button for a safety feature.

My question is.....is there a way to temporarily disable the Hymotion system completely. Maybe this isn't the issue, but it is about the only thing I can think of. Has anyone else heard of this scenario before? It was working just fine before this and showed no signs of any other problems.

 

Thanks so much for your advice!! I CAN start the car with the Hymotion system disabled after changing to the bridge plug.....thank goodness, I don't need to worry about getting a tow now!

I will likely need to check with Hymotion to see what the issue might be. When I revert back to the Hymotion again by unplugging from the bridge plug and going back to the other plug, the same issue arises. I also tried plugging into the bridge plug and starting the car...then while the car was started, unplugged the bridge plug and plugged into the other one.....when I did this, I could not turn off the car. Then I switched back to the bridge plug and could turn it off okay.

It really looks like it must be confused and think that it is plugged in and charging and is disabling the power button from doing anything.

At least my Hymotion is under warranty, so if worse comes to worst, at least it should be covered. I'll probably try to contact them to see if they have any ideas too.

Again, thanks so much for your advice. You saved me many headaches of trying to line up a tow for my car. Chances are my local dealership wouldn't even know about the Hymotion enough either to know to try the bridge plug.

Thanks, thanks, thanks!

 

Just thought I would post an update. I had to take my Prius to the nearest Hymotion service center in Winnipeg for service. It turns out they had to replace the battery. Since then it has been running like normal. It's nice to have my plug-in back again! They were very helpful....it was kind of nice going for a little road trip as I haven't been up to Canada for a while. I charged it up last night and ran it today and it worked well. The only difference I really noticed was when I plug it in the lights on the back only came on for maybe five seconds and then went off. If I remember correctly, the one I had before would have the rear lights on until it finished charging completely.

 

Just thought I would post another update....after I had my Hymotion system fixed on Friday 8/21/09, I had a problem three days later. I had driven it on Saturday through Monday on the Hymotion system maybe about 80 miles or so. On Monday, I drove it to work about 30 miles away. The Hymotion battery made it just about the whole way. I plugged in to charge and left for lunch at 11:30. I pressed the Power button and nothing happened. Then I pressed it again and the Hymotion system started just fine.

I drove about three miles to get something to eat parked the car. When I parked it I shut if off and turned it back on again to make sure it would start in Hymotion mode.....it did.

Then I went back to the car after eating. I pressed the Power button and nothing. I waited a few seconds and pressed again....still nothing. Finally I had to go to the trunk and plug in the bridge plug to deactivate the Hymotion system entirely. I could at least drive the car as normal.

I let the car sit for a couple days. I had the Hymotion switch off (no red light). I then plugged in the Hymotion system in the trunk and hit the Power button without hitting the brake. Then I pressed the brake and the Power button. The car turned on. I flipped the switch to on (red light)...and was able to drive with the Hymotion system and it ran as normal....drove about 25 miles after which I had about three bars left.

Then I parked the car at home. I let it sit for about 10 minutes. Then I tried to start it again.....I pressed the Power button with the brake....nothing. So I shut off the switch (no red light) and unplugged the Hymotion from the trunk and went to the bridge plug. I turned on the car in normal mode until the gas engine kicked in. Then I shut it off. I went back to the trunk and plugged the Hymotion back in. I then pressed Power without the brake...then Power with the brake. The car started. I flipped the Hymotion switch on (red light) and was able to use the Hymotion system again.

So far, it appears to me that I might have some type of a quirk which causes me to have to hit the Power button without the brake first, followed by hitting Power with the brake. If I don't hit the Power button without the brake first....then it seems like no matter how many times I hit the Power button (with or without the brake) it won't start in Hymotion mode. I am a little confused why it would do this now as I did not have this probably for the four months I ran the system operational before.

Anyway, I thought I would post this information as someone else might find it useful if they happen to run across a similar issue.

This kind of sounds similar to the other post in this thread about having to unplug the Hymotion and go back to the regular system and then back to the Hymotion except in my case, I seem to have to remember to hit Power without the brake first.