Key Not Detected

Try changing the battery in the fob again

 

[eJ, post: 2085252, member: 120870"]I read the other threads on the "Key Not Detected" topic and I could not find anything of use for my situation. I tried both fobs I have. I tried not having my cell phone on me.

Any assistance that anyone could provide would be much appreciated.

Thank you so much.[/QUOTE]

Just to cover all of the bases, the typical Key Not Detected issue noted on here, other than battery related, is usually the liftback door not completely closed.

 

Check the voltage on the fob battery with a digital multimeter. If good, it should be around 3.00.

FWIW, I was getting "Key Battery Low" warning (second time around). Got a new battery, it read 3.00 volt. Check the old one, it read 2.98~. So not sure what's going on...

Still, measuring the voltage will help eliminate one of the unknowns I think.

Isn't it great how to the point these messages are?

 

LOL - I am having issues trying to post at work so I gave up on the details !

 

There's a benefit to the posting delay: while the (useless) progress bar is crunching away, you have time to proof read. When it gives up, you can still edit, then the second attempt to post invariably works.

A new wrinkle: I tried to fix grammar error in a previous posting. I could change it in the editor, but reposting would not take. But when I'd go back into the editor, the correction was still done, lol.

 

Besides the key not detected notice. If your rear hatch is ajar, it would also keep your rear hatch light on which would also drain your 12 volt battery! Reason for dead battery.
I would turn that light off so that will not happen.
Hope this helps!

 

Okay, my father-in-law insisted on driving my Prius today and he couldn't figure out how to lock the car and did something by locking it when still in drive or something that I can't figure out!

When I am outside my Prius the display will say "Key Not Detected" and not allow me to lock the car (unless I use the physical key). Almost like it thinks the power is still on and the car running.

• I have tried 2 separate fobs (could both go bad at the same time?)
• I have replaced the battery in one of the fobs
• I have made sure the rear hatch is closed
• I have tried disconnecting the 12 volt battery and re-connecting
• I have tried with no cell phone near the car
• I have searched all over the internet for anyone reporting a similar and the closest I found was this thread with no resolution ever posted.

Something in the manual talked about this being caused by trying to manually lock the doors while in drive and to press the Power button then unlock? That didn't help either.

Can anyone please help!?

 

There is a sks button under the steering wheel, by your knees, make sure that's pressed on

 

I find no such button in my C.

Does this condition also prevent you from driving the car ?
If not, I suggest a dealer visit.

 

The issue is resolved.

I wish I could post a precise answer here for future users but I'm afraid I'm not exactly sure why it's working now. After doing all that is listed above I realized I'd just have to take it to the dealer in the morning but I found the only way to get it so that no lights were on in my car overnight was to leave a set of keys in the car and lock it manually with the physical key.

So I left it that way for a few hours and then went outside late in the evening to take out the trash and decided to hit my fob button to see if it worked and lo and behold it did. So maybe something reset because the keys were in the car for an extended period? Anyway, I hope that possibly helps someone in the future.

 

I come back from the future, with some things in GENERAL about fob and prox remotes:

1. Some remotes and fobs will lose sync with the vehicle if buttons played with while out of range of car. Kids given keys as a toy, is a favorite.
2. Button cell batteries, when NEW should read about 3.15, a bit above the stated 3V stamped on them. BELOW 3.0 has been a problem in some remotes
3. Not all button cell batteries are identical. We replace batteries all the time for people, and OCCASIONALLY have found a make and model year that HATES Maxell or Panasonic batteries of the SAME CR number. It may have to do with the contact clips on the remote and slight shape variances of the perimeter seam of battery. A Good Automotive Locksmith can use a device to measure the frequency output of the remote. And reprogram or replace as needed.PARTICULARLY certain Honda and VW remotes.
4. Changing the cars' battery may throw out the keyless entry and long-range detection of remote ( but not the starting capability if you follow the dead remote procedure to start )
5. Charging of battery. Prius may require a specific procedure for jump starts.The ECU hates it done wrong, check owners manual for proper jump start procedures.
6. I would thoroughly inspect vehicle for an additional remote/prox/fob. Cars act wonky if a lost one is wedged in the seats, trunk, under car with a dying battery. I preferred when you HAD to put the fob into a SLOT, to emulate a key operate car.

Diagnostics on a vehicle is MORE valuable than parts and wrenches. The general public does not embrace this as having any dollar value. If you have a really good dealership, patronize them. Not every area has one that is great. There are excellent aftermarket repair options. Make sure they are professional shops.

I recommend a locksmith first, after you hunt for missing remotes/fob/proxii

 

The fob battery could read 3.00 volt but still it has low mah.

 

I've had the dash warning about low fob battery, checked the voltage and read 3.00.

 

My car does this a good bit. I replaced the key fob battery a couple of times and that didn't help. Only thing I can come up with is there is a minor short in the key fob. When I get the "key not detected", I gently tap the fob on the steering wheel and that fixes it. I need to buy a new fob or take it to a locksmith to attempt repair, but I just haven't gotten around to it.

 

Check under the steering column. There is a reset button. It should be unpushed. I learned this the expensive way but discovered the answer after reading postings on this forum. Some very good info. for those who want to save time and money and frustration. Thnx all.

 

The button you are referring was not included in the Gen III Prius. The design is different from your 2007 (Gen II Prius)

 

Probably unrelated, but the key fob for my Prius had its battery die (after several years of use), but when I replaced it, the next one only lasted a week or two. I thought the batteries I bought were defective, but it turned out there was an issue with that fob that was causing it to discharge the battery very quickly. I put a new battery in it and the voltage (via multimeter) dropped by about a tenth of a volt in just a couple of hours.

I switched to my backup fob and it was worked just fine since then. I hope that one outlasts the first one or I will need to shell out for a new one.

 

might one of the buttons be stuck down?

 

I don't think so - I had it disassembled during the time that I did the voltage test, so the button "caps" were separated, and the buttons are all still "clicky" and tactile.