Feb 262012

ELM 327 Bluetooth OBD2 Adapter

Just purchased a 2012 Prius V (why have I not written about that yet?) and one of the more active topics on the PriusChat forums is how to disable the annoying backup beep that sounds continuously while you are in reverse. Now, you might think that a backup beep is a great feature. Only problem is this beep is very loud and is only inside the car! It cannot be heard by those behind you as you would expect.

In the previous Prius incarnations you could hold your tongue a certain way and press a series of dash buttons along with your key fob to disable this ‘safety’ feature. Now, Toyota says to take it to your local dealer for them to make the change. Only problem is many dealers don’t even know it can be done (or at least the people you and I would talk to don’t) and many new owners report that the dealer wants to charge anywhere from $50 to $100 to do a 2 minute job. Some dealers do the right thing and turn it off free of charge but some only do it after the owner called Toyota corporate and complained.

Me, I know my dealership would do it if I asked but why have them do something that I can waste hours figuring out for myself. First, I needed a way to talk to the car’s computer. I had already bought ELM 327 Bluetooth OBD2 scan tool from Amazon that plugs into the ODB-II slot under the dash so I could monitor some of this little hybrid’s inner workings (here is another post I should have written). The device uses bluetooth to communicate to the outside world and wouldn’t you know it, a number of Android apps have been written to accommodate. (Note: Seems that the OBD2 port has a constant power supply, so even if you turn the car off the device stays on as does the Bluetooth, so probably best not to leave it plugged into the car overnight any more than you would leave your dome light on.)

Seemed like this little scan tool should be able to send data as well as receive, so now I just had to figure out how. I tried using the android ‘Torque’ app that I was using to monitor the vehicle but had no luck then I remember I had seen a program called ‘ELM 327 Terminal‘ which claimed to allow you to communicate with the ELM 327 adapter, sending commands to your hearts content. My first attempts to just send the strings I had seen in the forums did not work. Then I ran across a post explaining how to send these commands to a USB connected ELM327 device using a laptop and a terminal program and figured the same commands should work with the ELM 327 Terminal Android app as well.

Out to the car. Plugged in the ELM327 device. Activated Bluetooth on my phone and told the terminal program to ‘connect’. I had the terminal program send a AT I command just to make sure I was communicating with the device. Now I crossed my fingers and hoped for the best. I turned ‘Timer’ (right side of screen above ‘clear’) off otherwise the command you send gets sent over and over again. (Not sure it matters but in case it does, I had the car ‘on’ with the ‘Ready’ light showing and all the doors were closed.)

First we need to tell ELM327 where to direct our commands, in this case we want to talk to ECU (engine control unit?) 7C0, the combination meter.

Type: AT SH 7c0 (hit ‘Send’)
Returns: OK

Type: 21ac (hit ‘Send’)
Returns: 61 AC 00 (00 means continuous reverse beep)

Type: 3bac40 (hit ‘Send’)
Returns: 7F 3B 78 (no idea :)
Returns: 7B AC (meaning done)

Type: 21ac (hit ‘Send’)
Returns: 61 AC 40 (40 means only a single beep now)

Now for the real test, I popped the Prius into ‘Reverse’ and joy! joy! only 1 beep. Guess now I will have to figure out what other options I want to configure.

  75 Responses to “Programming a Prius to Disable the Backup Beep”

  1. How to set it back to continuous reverse beep

  2. Instead of 3bac40 send 3bac00

  3. Prius V 2012. Works exactly as described. Thanks.

  4. Where did you get a list of commands to send to change the settings? is there a list of them somewhere to download. That way can change other settings?

  5. Worked like a charm! Thank!!

  6. On my V2, OBD2 never returns an OK. For every command, I get the response “ELM327 V1.5” and the reverse beep is still continuous. Any thoughts? Thanks.

  7. Worked like a charm in 2013 Prius V Five. Thank you!

    When using ELM327 Terminal, need to make sure to type in the command in the small box at the bottom left, and not on the larger box.

    • Hector, Thanks for the clarification. I have not had a chance to play with any programming since I wrote this article. Would love to find some more things to ‘fix’ :)

  8. Thanks! Bought a $12 ELM 327 adapter from Amazon and followed your instructions. Worked great on my 2012 Prius III. Now if only a had a similar proceedure for the seatbelt beep….

  9. In the elm 327 terminal you need to type in the small box in the bottom left of the screen. If you type in the big whit area above where it keeps showing elm327 v1.5 it is not actually sending a command. The directions worked for my 2010 base model Prius!

  10. Worked on my 2010 Prius IV. Thanks a lot. Perfect instructions.

  11. Thank you! Worked great in my ’13 Prius III. The terminal program was a little buggy but it worked.

  12. Is there an option for one short beep in reverse, or is it one long, continuous tone as long as the car is in reverse?

  13. Any possibility to disable the lockout on the navigation map. Above 4 or 5 mph, it locks so that no additional input other than a very limited number of commands such as stop navigating.

  14. LOVE IT! I’m finally beep free!!! thanks!

  15. now if I could only switch from Fahrenheit to Celsius….

  16. One more to confirm that this works perfectly (I have a 2010 Prius base model). Such a greater pleasure to drive it now- and to think, the service guy at my dealer told me that this couldn’t be done. Can’t wait to show him that I knew better! Now, on to discovering how to disable that seat belt beep…

  17. PLEEEEEEASE let me know if you get the navigation/DVD player lockout with this as i don’t want to mess with any wiring to do the bypass…

  18. Just turned off the beep in our 2013 Prius – now it just beeps once when we put it in Reverse. Thank you SO much!

  19. Thanks for posting this how-to. I just tried it using OBD Car Doctor app and a BAFX OBDII adapter I got on Amazon for about $20 (couldn’t get the ELM 327 terminal app to work, but the Car Doctor console feature worked fine).

    Now beep-free (well, one beep I can live with). This was a lot cheaper than paying $80 at the dealer. Best, Terry

  20. My problem was I wasn’t connected to the program or the bluetooth wasn’t connected. I saw the option on the lower part of the screen to connect. The send button went white, I was able to type in the commands in the lower left small box, hit send 4 times, and WOW it worked. Now only one beep instead of that annoying series of beeps. Thanks so much for your help. Can’t wait to see my wife’s reaction when she backs out of the garage in the morning haven’t told her. It bothered her more then me. Thanks again. Greg

  21. Hi Gary,

    Thank for your guide, unfortunately on the 2013 Prius V I get more characters than “61 AC 00”. This makes me worried about what I’m doing.

    Can you post any reference material on what each code means? I’d feel a lot more comfortable if the instructions included what each code means.


  22. hey i have obd2 adaptor. can i connect through iphone??

  23. when i try to connect to adaptor through samsung S3 it says “java.io.IOexception:Permission denied” and SEND button is still white what should i do??

  24. Yes, confirmed this works. Did this on my 2010 Prius 2 using the same OBD2 Diagnostic Interface on my Motorola Droid.

    Now, how to disable the annoying seatbelt beep? I always pull in my neighborhood within 100 feet and pop my seatbelt off, its annoying to have to keep it on everytime i pull in back to the garage.

    Does anyone have instructions on how to disable seatbelt beeping for Driver and Passenger?

    • Use code 3ba700 to disable the seat belt chime :)

    • Hey, can you please confirm that it works on Prius gen 2? I’ve got a P2 2006 (facelift) and it doesn’t worked for me. On the second command i receive NO DATA. Can anyone please help?

  25. Hi. I bought the same elm 327 connector as you. However, I am unable to connect when I type in 21ac. Any idea why?

    When I type in at sh 7c0, it returns with ok. But when I type 21ac I get an “unable to connect error”. Because of this I cannot program my 2010 prius seat belt beeping to a single beep

  26. Gary’s instructions allowed me to turn off the hated seat belt chime and the reverse chime using the elm 327 and the free elm 327 terminal. Thanks Gary. Now what I want is a list of Prius specific CAN codes to tweak other settings. ie. My headlights when on auto do not turn on soon enough, (it’s really dark before they come on). Does anyone have the code for that?

    • On page 593 of the manual, there is a section that talks about the Light sensor sensitivity, but if you do not have a Navigation or Display that may have to be modified through a code like with reverse beeper, which is probably what you meant in your post.

  27. I’m thinking about trying this but worried about possible “extra codes.” Wondering if you ever resolved your question or felt reassured that you hadn’t inadvertently reprogrammed other features… Thx!

  28. Re the extra codes comment I just submitted – I was intending to direct it to Bob Smith (comment #22)

  29. Has anyone tried this with an Iphone 5?

  30. Thanks a lot Gary for this super process description . Makes me saving 70€ ( 100$ , I’m from France ) Thanks to Hector for the “small box” tip . Fyi, My Prius 3 dated from Nov 2009.

  31. Thanks for the wonderful process description. Worked perfectly on my 2012 Prius IV.

  32. Thank you so much!

  33. Just wanted to let you know that this post inspired me a few months ago to include Toyota settings (such as this reverse beep) in my own Android app… which I’ve just released. It’s called Carista. Basically, it provides a UI for the same kind of commands that you’ve described here. So no need for a terminal! Thanks for this information in the first place :)

  34. Hi!

    So… I read the initial post… and was going to say that there’s an app for Android called Carista that has a bunch of parameters that can be programmed… including the Reverse Beep… But I see that the author has beaten me to it. :) Now, given that the procedure for the reverse beep is described here and can be done with a simple terminal, it would be cool that this one was included for FREE in Carista (as a demo of what can be done, to encourage others to pay for the other options).

    What I would love to be able to do is configure the automatic turn on of the main car lights when I turn on the car (it’s now mandatory in Switzerland to drive with lights on, so I would like to make them turn on automatically). :)


  35. About to try the instruction on disabling the reverse continuous beep… Any instruction on getting rid of the seat belt beep?

  36. Confirmed seat belt chime disable!!

    Use code “3ba700”

    -Send: AT SH 7c0 -Reply: OK -Send: 3ba700 -Reply: (some nunbers)

    Here’s the link I used for code reference: https://docs.google.com/spreadsheet/lv?key=0AiHL0r_2nhUEdF9lVVBxOVNoN3Zva3E0NmdZTUR1eVE&hl=en#gid=5

  37. THANKS! The reply codes were slightly different on my 2013 Prius, but it did work.

  38. And it works on a new 2015 Prius… the terminal program would drop the connection after each command, and I had to reconnect, but it made it.

    The return codes had some extra data at the beginning, but the end of each return matched what is posted above, and the results were correct.

    Thanks so much!

  39. I used the Carista app successfully to disable the reversing beep on my 2012 Prius Plus. I first bought a cheap ELM327 adaptor on eBay, which the app could communicate with but it could not do customisations.with it. I then bought another marginally less cheap one and that worked fine. Carista spells out the customisations, rather asking you to send codes. I was also able to disable the seat belt alarms for driver, front and rear passengers, which was a bonus.

    You have to buy the pro version for £15 in order to do customisations, but I do not begrudge it. I may need to switch the seat belt alarms back on for the MOT, so it will continue to be useful. There were a number of other customization options, but none which I would be likely to use.

  40. It worked for my Prius 2011 Gen III but did not work for two Priuses 2015. The code 3bac40 returns 7C80361AC00 and 21ac returns 7C8037F3B78. Any solution for this?

  41. Your mileage may vary (i.e. if it breaks, don’t blame me), but I did it on a 2015 (as posted above) and it worked. The return codes had some extra “stuff” at the beginning, but the last digits matched up with what was listed above.

  42. Worked! : 2016 gen4 Prius … 3bac40 == setting to disable backup beep and 3ba700 == disable seatbelt crazy beep

  43. Works fine for 2016 Prius.

  44. Works perfectly on my 2010 Prius IV – THANK YOU!

  45. Gary – worked like a charm on my 2010 prius. THANK YOU so much, a life saver. Wouldn’t have trusted the Toyota garage, in fact they seemed oblivious to the fact it could even be turned off.

  46. Thanks, worked on my 2015 Prius using iPhone. Had to turn off home wi-fi, this was interfering with ELM327 wi-fi. Used OBD Terminal app. You have to use the Command list (SH xyz) to set the header instead of just typing the first line AT SH 7C0. All other commands can be entered from keyboard. Firstly I also set the protocol instead of using Auto Detect, again you have to use the Command list (SP h) instead of AT SP 6 – 11 bit 500 kbaud. For those that get extra characters at the start of the reply, this is because you have headers on in your responses, headers can be turned off with AT H0

  47. Worked like a charm, here is my setup for anyone else that might care:

    1. Mac OS 10.11.6
    2. ELM327 v1.5
    3. Needed a USB to Serial driver, used PL2302 ( http://pbxbook.com/other/mac-tty.html ) PL2302
    4. Downloaded and used goSerial to talk with the car (2010 Prius) -> does show Buffer Full with ATMA code, but no clear answer on how to avoid this yet….
    5. Followed instructions to veriify it worked ( https://theksmith.com/software/hack-vehicle-bus-cheap-easy-part-1/ )
    6. Then I followed the above instructions to make it work ( http://dogberrypatch.com/archives/programming-a-prius-to-disable-the-backup-beep/ )

    No, how to we get the darm seat belt beep to never ever return.. ?

  48. Thankyou so much Gary, It worked brilliantly for me, now the constant reverse beeping is set to beep once only on my 59 reg Prius. Really needed this so I can now actually hear my reversing sensors when parking up.

  49. This worked for me, so grateful for it!

    It took me a while to find a Terminal app that worked (for some reason ELM 327 Bluetooth OBD2 Terminal would not connect), but the one I found was Kwik OBD Terminal (on Android LG G4) and it did exactly what I needed. No more seatbelt beep, and just the single beep when I put it in reverse!

    Has anyone done any other hacks, such as changing the keyless entry settings to unlock all doors when driver’s door is opened?

    • Donovan, The door unlock procedure is done using the key fob…. The procedure is in the cars owners manual…

    • Donovan, get in your car with the car off. Hold hown the lck and unlock buttons on your remote at the same time and a display of a car with all of the doors open will pop up on the console. Now all your doors will open when you touch the drivers door handle. To reverse it do it again.

  50. I have one of those cheap OBD 2 from China. I tried for days to get my crazy beeper configured to beep just once but several different programs failed me. I finally tried your data input method and was disjointed to, after the input to get “No Data” response. I think I tried at least 20 times before I gave up on “No Data”. The next day when I backed my 2015 Prius out of the garage, One beep! Hallelujah! One beep! Thank you, you saved my life and my marriage! My wife could not stand that constant beeping! Thank you Thank you thank you!

  51. Can I use the same thing on the 2nd gen? Thanks

  52. Any body can help? Is it possible to check whether a seat belt beep is beeping through a specific PID?

  53. i see we’re still commenting after all these years. you deserve it. you nailed it. i got the belt chime off my 2011 with 3ba700 using the ELM327 OBD Terminal from play store and a samsung s4. the header returned as “ok” and the code returned “no data” but the chime is gone from both driver and passenger seats. many thanks

  54. Just wanted to comment and say thanks all these years later. I used and ELM 327 (or similar branded) OB2 Wifi connector i got off amazon for $14. Then on my iPhone 6 i used a very simple and free app called OBD2 terminal to send commands to my 2014 Prius (gen 3) and disable both the reverse and seatbelt beeps using the instrucitons above and in the comments above.


    At its base, this is about freedom…Toyota step off my personal choices in safety…ridiculous what is done in the name of “safety” and “security” these days….f off….

  55. Brilliant, thank you! Had to navigate through several apps to find how to turn off the pesky backup beep. Finally found “ELM Basic” to work perfectly on my 2015 Prius and your original instructions. Thank you!!!!

  56. Worked perfectly with 2017 Prius v in Australia.

  57. Thanks so much! The beeping was distracting and driving me nuts, no pun. 2015 Prius here, used Car Scanner app, saved $10 subscription for Carista. Thanks again.

  58. I was able to replace the continuous reverse beep with a single reverse beep as described. Is there a code to completely eliminate the reverse beep (eliminating even the single beep)?

  59. Worked perfectly.

    Thanks so much!!!

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