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Electronics Going Haywire After Battery Died

cblanchard

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2026 3.0 Premium MT Toyota Supra
For reference, I have a 26’ premium MT with drivers assist package (this is important for later)
Ohio got a cold front and a lot of snow a couple weeks ago and I left the supra outside from Sunday (when the snow hit) to Wednesday (the first time I tried turning it on after sitting). I cleaned the snow off of it and moved it around, let it run a bit on Sunday and Monday but let it sit all day on Tuesday. Tried to turn it on Wednesday morning and the starter was frozen but I then thawed out the starter for the whole day while repeatedly trying to turn the car on. For the first couple tries of turning it on, the battery was fine, but eventually it went out and kept going out even after jump starting and charging it. Eventually that same night the whole car turned on (including battery) but my dash looked like a Christmas tree.
There were around 11 notifications that popped up on the screen, all were electronic. All driving assist turned off, parking sensors are wack, blind spot monitors off, gas gage (including tank and mpg) was wack, power steering was off, chassis stabilization was needed, and eventually my airbags turned off too after two days. Took it to Toyota that same Friday and they said most of the codes would fix themselves but they needed to run a diagnostic and it would take hours so I made an appointment for the next Friday because I didn’t have a ride until that day.
Drove the car every day since that day and none of the codes fixed themselves so I dropped it off at Toyota the next Friday and they replaced the battery (without asking) but called and said that I still had codes on my screen and asked me if I wanted to fix them (that was the whole reason I took it in in the first place). They also tried blaming my battery dying on my radar (it’s wiretapped instead of being in the cigarette part) but I explained to them I’ve had it on there since the day after I bought it in September and I even left my car for two weeks while I was away in November and no problems with the battery came up. I also told them it turns off and on with the car since it’s on battery saving mode (I have the uniden R7) so it shouldn’t be taking THAT much battery.
They called me on Monday and told me that the codes were caused by my aftermarket headlights and taillights (iilumo drls and alpharex taillights), I asked them which codes specifically because there weren’t any problems with my headlights or taillights and they couldn’t answer. I’ve also had the headlights and taillights since early October and early December, both of which turn off and on with the car. It’s Wednesday and they still haven’t told me any other thing other than blaming it on aftermarket parts that have little to no relation to my actual problems.
I saw another thread that said I need to lock the car each time I leave for everything to turn off correctly but I’ve been doing that since the day I bought it so it can’t be that. Just wondering if anyone else is having these problems with the cold and such especially with the newer models
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puzzled

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.. so is there a question somewhere in there?
 

puzzled

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Last sentence brochacho
I think your car just needs to be driven more or put on a battery tender while not in use. I've had my Supra unlocked in my garage over 2 weeks no issue starting the next time. But that was after the car was fully charged with a battery tender. You can get one on Amazon for like $40.. man those things use to only cost like $20.. a couple of years ago.. I use the BatteryTenderJr. Compatible with lead-acid and AGM.
 

BrodoFratgins

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I hate electric troubleshooting, but here a few shots in the dark I came up with from looking at various BMW forums:
  1. Original battery was failing and Toyota didn't register the new battery
  2. New battery is the wrong type of battery (doubtful, but check)
  3. Water intrusion from melting snow?
    1. Aftermarket headlights/tails are notorious for leaking. Water intrusion could have caused a short.
    2. Check BCD fuses?
  4. Battery may need to be left disconnected for an extended period of time too to allow codes to clear?
 
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cblanchard

cblanchard

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Thanks! I believe they did code the new battery and gave it the right one (atleast that’s what they told me) but I haven’t even thought of the water from the taillights and will be checking that once I have the car back, a person from Toyota corp is checking it out at the dealership at the moment
 
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cblanchard

cblanchard

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I think your car just needs to be driven more or put on a battery tender while not in use. I've had my Supra unlocked in my garage over 2 weeks no issue starting the next time. But that was after the car was fully charged with a battery tender. You can get one on Amazon for like $40.. man those things use to only cost like $20.. a couple of years ago.. I use the BatteryTenderJr. Compatible with lead-acid and AGM.
Thanks but I daily it, around 1-1.5 hours of drive time a day. When I leave it for even 24 hrs I leave it on a battery charger which says it’s fully charged after a couple hours. I’m thinking it may be something related to the starter freezing because they gave me a call yesterday and said I never told them about the starter freezing (even though I told them multiple times) and acted like it was a big deal which made them finally call up someone from Toyota corp to check it out. I will be checking on my battery charger though, thanks!
 
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cblanchard

cblanchard

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Question marks aren't just for grade school.
Last sentence was more of a statement than a question, I assumed most people would get what I was trying to ask but I guess not.
 

razorlab

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Def on your own with aftermarket headlights/taillights. Most of those things are garbage so I wouldn't be surprised if those were at the root of your issues.
 
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cblanchard

cblanchard

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2026 3.0 Premium MT Toyota Supra
For reference, I have a 26’ premium MT with drivers assist package (this is important for later)
Ohio got a cold front and a lot of snow a couple weeks ago and I left the supra outside from Sunday (when the snow hit) to Wednesday (the first time I tried turning it on after sitting). I cleaned the snow off of it and moved it around, let it run a bit on Sunday and Monday but let it sit all day on Tuesday. Tried to turn it on Wednesday morning and the starter was frozen but I then thawed out the starter for the whole day while repeatedly trying to turn the car on. For the first couple tries of turning it on, the battery was fine, but eventually it went out and kept going out even after jump starting and charging it. Eventually that same night the whole car turned on (including battery) but my dash looked like a Christmas tree.
There were around 11 notifications that popped up on the screen, all were electronic. All driving assist turned off, parking sensors are wack, blind spot monitors off, gas gage (including tank and mpg) was wack, power steering was off, chassis stabilization was needed, and eventually my airbags turned off too after two days. Took it to Toyota that same Friday and they said most of the codes would fix themselves but they needed to run a diagnostic and it would take hours so I made an appointment for the next Friday because I didn’t have a ride until that day.
Drove the car every day since that day and none of the codes fixed themselves so I dropped it off at Toyota the next Friday and they replaced the battery (without asking) but called and said that I still had codes on my screen and asked me if I wanted to fix them (that was the whole reason I took it in in the first place). They also tried blaming my battery dying on my radar (it’s wiretapped instead of being in the cigarette part) but I explained to them I’ve had it on there since the day after I bought it in September and I even left my car for two weeks while I was away in November and no problems with the battery came up. I also told them it turns off and on with the car since it’s on battery saving mode (I have the uniden R7) so it shouldn’t be taking THAT much battery.
They called me on Monday and told me that the codes were caused by my aftermarket headlights and taillights (iilumo drls and alpharex taillights), I asked them which codes specifically because there weren’t any problems with my headlights or taillights and they couldn’t answer. I’ve also had the headlights and taillights since early October and early December, both of which turn off and on with the car. It’s Wednesday and they still haven’t told me any other thing other than blaming it on aftermarket parts that have little to no relation to my actual problems.
I saw another thread that said I need to lock the car each time I leave for everything to turn off correctly but I’ve been doing that since the day I bought it so it can’t be that. Just wondering if anyone else is having these problems with the cold and such especially with the newer models
Update: Toyota corp says they won’t touch my car unless I remove the drls and disconnect the radar even after telling them that I’ve had these on it for months and that can’t be the problem. Don’t deal with Toyota west in Columbus!
 

razorlab

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Update: Toyota corp says they won’t touch my car unless I remove the drls and disconnect the radar even after telling them that I’ve had these on it for months and that can’t be the problem. Don’t deal with Toyota west in Columbus!
I’m sorry, how are you surprised that a dealer doesn’t want to touch your car after you modified it? Like really?

To put them on blast is like peak entitlement.
 

Eastwood

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Update: Toyota corp says they won’t touch my car unless I remove the drls and disconnect the radar even after telling them that I’ve had these on it for months and that can’t be the problem. Don’t deal with Toyota west in Columbus!
Considering it’s all electrical and you’re having electrical issues, that’s normal. If you brought it in for suspension issue they’d handle it.
 

AngryCar

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Sounds like water got inside something from the snow and is causing issues.

I have a 2020, I don't drive my car from Thanksgiving to mid-April because of winter, we get about 80 inches of snow on average. Car is covered and stored in my non-heated garage. I have never put a battery tender on it, I leave my radar detector plugged in, and while stored I start it once a week and let it run for 30 minutes so it comes up to full temp. I have never had any issues starting it even when it's been below zero outside, probably 20 in the garage. Not even close to an issue. The OEM AGM battery lasted 5 years. Cold temps should give you zero issues. My guess is water from the snow shorted something out.
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