I have a 2010 model IV with 150,000+ miles. A few weeks ago, I noticed my car horn would beep slightly whenever I start my car. Someone suggested checking my key remote batteries. Unless both batteries are low it beeps with both keys. The next suggestion is to check the 12v battery. I found a Youtube video for a Gen 2, i tried the same but could not get a digital display value for 12v usage. If you know how, please provide detailed steps that takes me to the 12v battery display. Thanks!
Once you're in the MFD diagnostic screens (I assume you have one of the touch-screen models; I have no idea what diags are available in the LCD radio-only versions), look for the "vehicle signal check" screen. The voltage is there, along with the status of the parking brake, taillight, and reverse signals. Be aware that the voltage shown there is typically a good fraction of a volt (say, .6 or .7) lower than what you would measure at the battery itself, which means if you post the reading on PriusChat you may attract responses that emphasize how low it would look on a voltage-vs.-state-of-charge chart, and will have to keep your head about you. -Chap
We have them on a 4 year replacement -- if you still have the original .... replace it. It seems the OE batteries are not as strong as the better replacements. Its an odd size and very small.
This is for the NAV display: 1. Start with headlights off and car off. Have everything on car off (radio, etc.) It may be best to do this after the car sits overnight. 2. Keep foot off brake pedal 3. Push POWER Button twice 4. Hold in "INFO-PHONE" button on right side of NAV/Headunit display and keep it in while doing next step. 5. Turn headlights on and off three times quickly - hidden diagnostic menu comes up. Release "INFO-PHONE" button. 6. Press "Function Check/Settings" on NAV display. New menu comes up. 6. Press "Vehicle Signal" on NAV display. 7. Battery Voltage is displayed without load. Record it. 8. Turn headlights on, radio, press brake pedal, anything else you can think of to put a load on the battery. Battery Voltage is displayed with load. Record it. Turn off everything. 9. Place foot on brake pedal and Press POWER button to turn on the car. (Ready status). Record new reading. 10. Press POWER button to turn off car, which takes you out of diagnostic mode. Car and display will now behave normally. Search here for info on what voltage readings indicate a healthy battery. Or, don't bother and just replace the battery.
