System Malfunction - Trailhunter 5' Hybrid iForceMax - Bad Battery Cell?

[Lets_Taco_Bout_It]

After a long weekend, I went to start the truck this morning and was greeted by the warm glow of dashboard warning lights and a cold engine. What's peculiar is that I didn't turn the truck on all weekend. Dropped off the truck this AM (11/4/24). Waiting to get a call back from Burien Toyota.

Got a call from the dealer and they mentioned that according to their diagnosis, they're saying it could be a bad battery cell. I also found out today that you CAN jump start a Hybrid vehicle, and the new method is BRAND new to this generation. There is a dedicated terminal in the fuse box under the hood, even though that isn't where the battery is.

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[StreeTaco]

So it didn’t start, is what you’re saying correct?

 

[TacoFreak]

My wife had a battery electric Lexus. If she leaves it parked for very long and the app connected it runs down the 12 volt battery to the point where you can't even open the doors. The Lexus service department said it was a known issue with no fix yet, and the only solution for now is to log out of the app.

It is interesting to see what the jump start process is on a hybrid @Lets_Taco_Bout_It. I read something about that before but I had forgotten the details which are good to know. I also noticed that your mileage is about where mine is, which is 7-8 mpg lower than advertised. Have you asked your dealer about that yet?

 

[Lets_Taco_Bout_It]

So it didn’t start, is what you’re saying correct?

Correct. Kind of. It seemed like the electrical systems kicked on but the gas motor didn’t turn over.

 

[Lets_Taco_Bout_It]

My wife had a battery electric Lexus. If she leaves it parked for very long and the app connected it runs down the 12 volt battery to the point where you can't even open the doors. The Lexus service department said it was a known issue with no fix yet, and the only solution for now is to log out of the app.

It is interesting to see what the jump start process is on a hybrid @Lets_Taco_Bout_It. I read something about that before but I had forgotten the details which are good to know. I also noticed that your mileage is about where mine is, which is 7-8 mpg lower than advertised. Have you asked your dealer about that yet?

I could understand if it sat for a week or longer, but this was Friday to Sunday night :/ I don’t plan on using this as a daily driver so I’m hoping it can sit for 5-7 days at a time without the need for a trickle charger.

I did mention it to them and they seemed convinced that there’s not enough data for it to show true mileage. I do live near downtown Seattle but I’ve been feathering the throttle and not pushing the motor to excessive RPM. I don’t know what else could cause the poor mpg. I did switch the tires to 275 KO3’s that are E rated (heavy) but I can’t see it impacting the mpg that severely. I see people getting close to 22 mpg.

 

[TacoFreak]

I could understand if it sat for a week or longer, but this was Friday to Sunday night.

Pretty much the same with my wife's car, she drove it a couple of times one week, parked it on Friday morning and by Sunday night it was dead. Their first thought was also a bad battery, but when it was fine they said it was the car doing constant status updates to the server. It hasn't done it again since she quit using the app, so maybe that is true.

I did mention it to them and they seemed convinced that there’s not enough data for it to show true mileage.

I know some people average 22-23 mpg with the same miles as my truck. One guy I talked to said there was no way he could flog his truck hard enough to get it below 20.

Mine was up to 17.4 mpg and I assumed that it was influenced by the early break in/slow driving miles. So I reset it and drove about 50 miles of mostly freeway and now it is 15.5 mpg. Some variation is understandable, but 7-8 mpg between identical trucks seems like something is wrong to me. I will see what my dealer has to say, but I am expecting something similar to what your dealer said.

 

[Gfenza89]

Many many many questions regarding these new 4th gens…. Hoping you’re listening Toyota.

 

[Vincent907]

Pretty much the same with my wife's car, she drove it a couple of times one week, parked it on Friday morning and by Sunday night it was dead. Their first thought was also a bad battery, but when it was fine they said it was the car doing constant status updates to the server. It hasn't done it again since she quit using the app, so maybe that is true.

Did your wife just logged out of the app or did she actually uninstalled the app? My truck is on a barge right now and it'll take 10-14 days to get to where I live. I'm worried now the truck will have no battery left when it gets to the port.

 

[TacoFreak]

Did your wife just logged out of the app or did she actually uninstalled the app? My truck is on a barge right now and it'll take 10-14 days to get to where I live. I'm worried now the truck will have no battery left when it gets to the port.

She logged out but did not uninstall the app, and the battery drain went away. That is one reason I have never used the app with my Tacoma, because like @Lets_Taco_Bout_It my truck is not a daily driver. According to her dealer if someone is logged into the app the vehicle sends a steady stream of status updates and Toyota knows that will run down the battery. It is probably worse in an electric because they only charge the 12 volt when the vehicle is on and in certain driving situations. It may not be a problem with your Tacoma, but it might also be a good idea to log out for now.

 

[WKTJR1]

I've read this thread a couple of times, and I'm still confused. So, the 12V battery has a dead cell—was it replaced?

I can't speak for EVs, but logging out of the app doesn’t make sense to me. That would imply the app is integrated into the vehicle's control functions, and turning it off would end that control. From what I understand, the vehicle pings the app; if it’s active, it sends a status update, but if it’s not, the vehicle does nothing until you start it? If that’s really the case, there should be a TSB out or some other advisory for this issue—otherwise, it sounds like someone is just making things up.

 

[Lets_Taco_Bout_It]

I've read this thread a couple of times, and I'm still confused. So, the 12V battery has a dead cell—was it replaced?

I can't speak for EVs, but logging out of the app doesn’t make sense to me. That would imply the app is integrated into the vehicle's control functions, and turning it off would end that control. From what I understand, the vehicle pings the app; if it’s active, it sends a status update, but if it’s not, the vehicle does nothing until you start it? If that’s really the case, there should be a TSB out or some other advisory for this issue—otherwise, it sounds like someone is just making things up.

I will address this with the dealer. I’m hesitant to believe what my service adviser tells me b/c I feel like they’re trying to seem like “experts” but honestly have never seen this truck before so they are shooting in the dark. I will update the service log when I get it so we can review it.

Hopefully this doesn’t snowball into something worse.

 

[tacorancher]

This is weird. I recently went on a two week work trip and the truck started fine when I got home.

As for mileage, I just filled up and had 20MPG tank average after driving like a complete asshole. If I drive lightly I’m over 21. That said I use 89 octane which helps a ton. Also the KO3s are 20 pounds heavier per tire and also have more rolling resistance and larger diameter (although not much) - this will for sure shave off 1-2 mpg. Try 89 octane. Lastly I will say once I crossed 2400 or so miles the engine truly did break in and mileage went up. Before that I was 18 or under. I think it takes time for the 2.4L to hit its stride.

Let us know what happens with the battery.

 

[TacoFreak]

I've read this thread a couple of times, and I'm still confused. So, the 12V battery has a dead cell—was it replaced?

I can't speak for EVs, but logging out of the app doesn’t make sense to me. That would imply the app is integrated into the vehicle's control functions, and turning it off would end that control. From what I understand, the vehicle pings the app; if it’s active, it sends a status update, but if it’s not, the vehicle does nothing until you start it? If that’s really the case, there should be a TSB out or some other advisory for this issue—otherwise, it sounds like someone is just making things up.

At first this didn't make sense to me either. Lexus service said that when you are logged into the app, the app server pings the vehicle for status updates. So the app is not integrated into the vehicle in any way, but the vehicle does respond with its status when the server requests it. The server only requests status when you are logged in, to reduce latency. As a software engineer that does make sense to me, and since my wife started logging out of the app the battery has not discharged again. There was no TSB for that, but when the dealer's service department questioned Lexus they said it was a know issue and they were working on a fix.

From my understanding an electric only charges the 12 volt when the vehicle is on and regenning. So they are more susceptible to not keeping their battery charged. The two other cars (Toyota and Subaru) that share this platform have the same issue.

I also know that some hybrids have this problem too, but I have not seen any complaints with our trucks. But it does fit with what the OP saw and it could be the case for me as well.

 

[WKTJR1]

At first this didn't make sense to me either. Lexus service said that when you are logged into the app, the app server pings the vehicle for status updates. So the app is not integrated into the vehicle in any way, but the vehicle does respond with its status when the server requests it. The server only requests status when you are logged in, to reduce latency. As a software engineer that does make sense to me, and since my wife started logging out of the app the battery has not discharged again. There was no TSB for that, but when the dealer's service department questioned Lexus they said it was a know issue and they were working on a fix.

From my understanding an electric only charges the 12 volt when the vehicle is on and regenning. So they are more susceptible to not keeping their battery charged. The two other cars (Toyota and Subaru) that share this platform have the same issue.

I also know that some hybrids have this problem too, but I have not seen any complaints with our trucks. But it does fit with what the OP saw and it could be the case for me as well.

That makes sense. From a non-engineer perspective, it seems reasonable to simply reduce the frequency of updates to avoid this issue. Alternatively, an algorithm could assess variables like time of day, last time driven, and other factors to determine when the next update is actually necessary.

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