Transmission Warning

[smithBYU85]

Hi all,

I got a warning message from my Prius about the transmission last Friday night. I was with a friend at the local Sonic eating dinner when I got the error. The car was at a slight incline and not fully turned on, I hit the power button twice WITHOUT the depressing the brake pedal, so I could run climate control and the radio without the ICE engaging. After about 1.5 hours the triangle of death came on with some message about the transmission and it told me to put the car in a level spot and fully engage the parking brake, then release it. I turned the car on and the message disappeared and there were no indicators activated on the maintenance screen other than to change the oil and rotate the tires (it's not quite time yet for that). Of course I didn't do as it asked, I figured the warning would remain if it were a real problem. I haven't had any other warnings or problems. As far as I can tell, the car is performing as normal.

Anybody have any ideas what that was?

I have an 04 Prius with 78k miles on it.

[prius729]

1 1/2 hr in accessory mode is pretty long, especially for a prius. I'm betting it was a low battery warning. On one of my prior cars, when it was on low battery power the dash lights did some funky stuff.

[smithBYU85]

Yeah, that could be. If that's the case, I would hope the error would indicate that to be the issue. As a programmer, I know that most error messages are so horribly non-descriptive to be of any use, so I wouldn't be surprised. The car started as quickly as it always has at least and has run normally since. I don't remember the exact wording of the message, but it was something about the gear park in the transmission and I had to set the parking break and release it. Wish I could remember it.

[Patrick Wong]

Originally Posted by smithBYU85

I got a warning message from my Prius about the transmission last Friday night. I was with a friend at the local Sonic eating dinner when I got the error. The car was at a slight incline and not fully turned on, I hit the power button twice WITHOUT the depressing the brake pedal, so I could run climate control and the radio without the ICE engaging. After about 1.5 hours the triangle of death came on with some message about the transmission and it told me to put the car in a level spot and fully engage the parking brake, then release it...I have an 04 Prius with 78k miles on it.

To clarify, when you are starting from IG-OFF and press the POWER button once without pressing on the brake pedal, you will be in ACC-ON mode. This powers up the MFD and you can play the stereo.

If you press the POWER button again without pressing on the brake pedal, you will be in IG-ON mode. The dashboard warning lights will come on, you can lower the power windows, and you can turn on the fan in the cabin ventilation system. However the heating and cooling functions are not working.

I recommend against leaving the car in IG-ON mode for any length of time, as the drain on the 12V auxiliary battery is severe. This is why you received the warning message described above.

I hope that you have driven a sufficient length of time since this episode so that your 12V auxiliary battery has been recharged. If not, I suggest that you make the car READY and leave it as-is for 30 minutes or more, so that the 12V battery can be charged up.

Good luck.

[Bill Merchant]

And I'd recommend that if your 12V battery is the one that came with the car, you should do some research on 12V battery replacements. With a severe drain like that, your old battery may be on its way out. Might as well be prepared with knowledge when it dies soon.

[smithBYU85]

Originally Posted by Patrick Wong

I hope that you have driven a sufficient length of time since this episode so that your 12V auxiliary battery has been recharged. If not, I suggest that you make the car READY and leave it as-is for 30 minutes or more, so that the 12V battery can be charged up.

Good luck.

Thanks for the clarification, I'm not fluent in Prius lingo yet. I've only owned it for less than a year. Yes, I have driven it for long enough to re-charge the 12v battery. I drove from Provo to Salt Lake City and back on Saturday afternoon/evening, about a 100 mile trip.

I didn't plan to be in IG-ON mode for so long, my date and I were so engrossed in our conversation that time slipped on past.

Originally Posted by Bill Merchant

And I'd recommend that if your 12V battery is the one that came with the car, you should do some research on 12V battery replacements. With a severe drain like that, your old battery may be on its way out. Might as well be prepared with knowledge when it dies soon.

Good advice, I'll do that. I believe it is the original 12v from the factory. My parents bought it at 20k miles and never replaced it and I bought it from them last year. Do you recommend buying it from the dealer or any other parts location?

I'll chalk this one to my own stupidity and I'll be sure not to do it again.
Thanks!

[richard schumacher]

Yep, battery. Either turn the car OFF, or leave it ON and in Park (NOT in Neutral!), and you will not have this trouble.

[qbee42]

As others have implied here, a low 12 V battery will produce some scary and misleading messages. Think of it as temporary Alzheimer's for your car. Once the 12 V system comes back up, your car's thought process clears and the scary messages go away.

Tom

[jayman]

Originally Posted by smithBYU85

The car was at a slight incline and not fully turned on, I hit the power button twice WITHOUT the depressing the brake pedal, so I could run climate control and the radio without the ICE engaging. After about 1.5 hours the triangle of death came on with some message about the transmission and it told me to put the car in a level spot

This is the Prius way of warning you to NEVER EVER do that. You can seriously discharge the 12 vdc battery and - depending on how you enter ig-on mode - the NiMH traction battery.

You discharge the 12 vdc battery, you need a boost and possibly a new battery, +$150 depending on dealer. The 12 vdc battery is a special size and construction, including provision for a vapor vent tube, you can't find it at Pep Boys. Discharge the traction battery, you're SOL

If you want to run the climate control - I sure hope you mean just the fan not the A/C as well - you're lucky the battery lasted that long. The Prius has an automatic, variable speed electric A/C compressor. If you are in D or P, the gasoline motor will automatically start and stop to keep the traction battery charged. In N, it will NOT run, you could discharge the battery

The gasoline motor doesn't necessarily have to run to charge the 12 vdc battery. The inverter/converter will take energy from the NiMH traction battery to do that. Once the NiMH battery state of charge gets to the low threshold, the gasoline motor will start to charge it

This is actually a very efficient process, not at all like idling a regular car to run the A/C. So just put it in P, and let the car worry about the charge level. I've gone through automatic car washes with the climate control and headlights off, but radio on, and the motor stayed off the entire 10 minutes

You should consider fully charging the 12 vdc battery. The Prius 12 vdc charging system doesn't have quite enough omph to bring back a battery severely discharged. A regular automatic battery charger set at 10 amp position should do it, otherwise you may find your Prius going dead after sitting a couple of days

Please reference the attached Adobe pdf

[Patrick Wong]

Originally Posted by jayman

You should consider fully charging the 12 vdc battery. The Prius 12 vdc charging system doesn't have quite enough omph to bring back a battery severely discharged. A regular automatic battery charger set at 10 amp position should do it, otherwise you may find your Prius going dead after sitting a couple of days

Hi Jay,

Note that page 5 of TSB PG007-03 contains a special note highlighted in a red box: "Use of standard battery chargers is NOT recommended on the Prius 12–volt auxiliary battery, in order to prevent battery damage."

Also note that the label on the top of the battery recommends limiting battery charging current to ~4A...So it might be better, if using a regular charger, to set the charger to the 2A setting and charge at a slower pace.