Hello everyone,

Yesterday morning I was doing my usual check-up on my HS 250h using the Launch Creader Elite scan tool. During a standard health check, the tool showed a error codes from the telematics system. The error code B15EC, which indicates the back-up battery needs replacement. After looking up the code, I found that this repair is considered delicate and usually not a DIY job. The recommendation is to take it to a Lexus dealer or a qualified automotive electronics specialist. The thing is, I’m really trying to avoid going through a Lexus dealer since I know the cost will be high. My question is: Can I just buy a replacement telematics module from eBay and install it myself? From what I understand, Lexus won’t just replace the back up battery they’ll swap out the entire telematics module, which of course comes with a hefty price tag.

 

This is a new one as I had never heard of this part. It appears the back up battery for the telematics is located near it and they are usually inside the dash somewhere.
What are your symptoms? How does it drive and other functions operate? There are several used telematics modules on eBay.

Hybrid vs. Non-Hybrid: Be aware that the "telematics module backup battery" is distinct from the large high-voltage battery pack in a hybrid vehicle, which has a more complex replacement process

You need to have an independent hybrid or Toyota specialist check out your HS as at this point you do not know if it is the battery or the telematics. You cannot just pull a code and replace whatever part the code points at without further analysis as there may be something else causing the code besides the named part. It may just be a symptom. An independent Toyota or hybrid shop should be familiar with this situation.
A little internet searching should be able to find a few well regarded hybrid or Toyota shops in California (or are you in Canada?)

 

I found more information on a Toyota forum elsewhere

This battery only supplies power to the telematics system which does things like calling for help if you are in a crash and the main battery has disconnected.

Pre-Collison not avaible. Took the Prius to the dealer (Toyota Lompoc, CA), and they informed me that I had an error (B15EC) that was causing the Pre-Collision not to function. They said the part the error calls out (backup battery/emergency battery) does not exist. They said they could not fix the problem and said I was SOL.

And from another forum:

​​​​​​The error indicates an issue with the B15EC battery. Toyota calls it a MayDay/BUB battery as it is used in an emergency to dial out to emergency services in a colliision etc. Its a 12V Li-Ion battery and I believe the part# is 8677776040. Since it is a critical emergency component, I would suggest checking with your local dealer and get a genune one from them or you can get it from on of the online Toyota Delaers at a discount.

New one is expensive so you can try with a used one first. On the Sienna, the Mayday/BUB battery is located behind the passanger side Glove Box, in the ECU integration block.

1. Disconnect -VE terminal.
2. Remove the Passanger side scuffplate (all clips), the cowl trip plate (conencted to the scuff plate and car body with a clip and plastic screw)
3. Remove the glove box (similar to changing the cabin filter) and you should be able to see the BUB battery in the ECU integration block.
4. Remove the ECU Block (Disengage the clips, Remove two nuts & one bolt) and you should now have access to the BUB.
5. Disconnect the old one, Plug in the new one,
6. Conenct the _ve terminal, turn the VAN to ON (no start) and clear the code.
7. Start teh Van, see if the code pops back up. If it doesn't, disconenct the battery, button everything up.
8. If code pops up, find another used BUB as the used one is not good either (shouldn't be an issue with a new one)

 

Nothing is wrong with the car it’s running perfectly fine. No error codes or warning lights are showing on the dashboard, and there’s nothing indicating any issues from the car itself. The only reason I know about this is because my scan tool detected an error code. I looked it up, and it’s completely safe to keep driving. The issue seems to be with communication to the telematics module something inside it isn’t responding properly. When the scan tool runs its 60-second test, it triggers that specific code. The problem comes down to a small dead backup battery inside the module. The car still feels solid and has no mechanical issues at all. I also checked how much it would cost to fix professionally it’s around $600 to $800. To repair it yourself, you’d need to remove the module, open it up, desolder the old battery, solder in a new one, reinstall the unit, then clear the code with your scan tool. Easier said than done , but luckily, I have some soldering experience from college, so I might be able to handle it myself and save that money.

 

I think the emergency S.O.S. button activation costs a hefty amount per month to subscribe to. Pardon me in case I'm assuming, or wrong with my limited understanding, but shouldn't you not have to worry about the telematic battery, unless you're paying a monthly fee to be able to send for help using that S.O.S. button? When I was stranded, I pressed my red S.O.S. button, and an automatic voice came on and said: "sorry! because you're not paying $30/month, this summons for help feature is not gonna work for you right now" -- so I was like later for all that ! i'm just gonna call my usual tow truck guy

 

Agree with the comments above. If you do not like Lexus dealers, you will not be interested in transmitting your realtime vehicle error codes to Toyota on a regular basis.

the only purpose of this extra battery (in my RHD car, it's behind the glove box) is to fire up the telephone when there is otherwise no electricity in the car.

 

So this may be non-functional on most of our aging HS250h vehicles but we will not know unless we run a scan because it is something we will never use. Save your money and ignore it. It may not work any more even with a battery as it may be on the old 3G system that is no longer operational. The Toyota app for iHeart radio on my 2016 Sienna no longer works as it is 3G.

From AI:

Any factory-installed 3G-based connected services on a 2011 Lexus HS 250h, such as Lexus Enform, were permanently shut down on October 31, 2022. The 3G network retirement by telecommunication companies, not Lexus, caused these services to stop working on most 2010–2017 Lexus models, including the HS 250h.
Impacted services on the 2011 HS 250h
All subscription services that relied on the 3G network ceased to function after the shutdown. This includes:
Lexus Enform Safety Connect: Automatic Collision Notification, Enhanced Roadside Assistance, Emergency Assistance Button, and Stolen Vehicle Locator no longer work.
Lexus Enform Destination Assist: The live, 24/7 destination-assist agent is unavailable.
Lexus Enform Remote: Features like remote engine start/stop, remote lock/unlock, and vehicle finder are permanently disabled.
Lexus Enform Service Connect: Vehicle health reports and maintenance alerts are no longer sent.
What still works
The 3G network shutdown does not affect basic vehicle functions or systems that do not rely on a cellular connection.

 

Moderator is correct, system is inoperative even with the battery. We had a 2008 Impala
and long after the On-Star telematic system was out of trial subscription the unit in our car failed and
began drawing down the cars 12v battery excessively. Since it was not subscribed anyway
I ask the shop to just pull the fuse... nope, then you will not have the stereo radio either...
Ended up paying $400 to fix the On-Star module that I was not ever going to use!

 

That’s great news! Appreciate everyone’s input. I can rest easy now knowing that’s not something to worry about.