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A recent RAV4World forum discussion highlights the importance of knowing what to do and what to avoid when dealing with a car and a dealership that are constant sources of frustration.
According to the RAV4World OP, he is frustrated with two things concerning his car:
- The vehicle is unable to pump more than nine gallons of fuel into the tank.
- Since buying his car brand-new, he has had a battery drain problem.
With respect to the Toyota RAV4 fuel tank capacity problem, which has numerous forum discussions that we will not get into because it is not germane to the topic, here is a video that discusses shared complaints from other RAV4 owners:
Consumer Alert – 2019 RAV4 Gas Tank Design Flaw
RAV4 Owner Battery Drain Complaint
With respect to the battery drain problem the OP is experiencing with his RAV4, we can understand the OP’s frustration:
“Went to the dealership countless times about the battery drain issue, every time Toyota came up with a TSB (technical service bulletin). The dealer kept the car overnight each time and claimed that they had performed the software updates. For the last software update, I even had to pay out of pocket $200, as the car was out of warranty. If I correctly recall, the last software update done was based on T-SB-0089-21. The battery on the car still dies to this day if I am not driving it for more than 3 days. At some point, the dealer replaced the 12V battery under warranty.”
Given that the vehicle is past its warranty period, the OP makes a wise decision by seeking help on the Reddit RAV4WORLD forum before proceeding further.
The OP asks three questions:
1. What is the TSB that definitely solved the DCM battery drain?
2. If I buy the Tech Stream software, can I apply the update myself? If not, I will go to a dealership to have it done (obviously not the one run by crooks).
3. Is there anything that I can do about the gas tank still not taking more than 9 gallons at this point (If I really want to fill up the tank, I have to pour the rest of 3-4 gallons slowly)?
As such, some very useful suggestions emerged that will help the OP avoid making some costly mistakes.
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A notable thread post comes from FKHeath (a recognized RAV4 forum expert) who replied:
- T-SB-0089-21 REV 1 (released April 11, 2022)
- No
- There is a reserve space at the top of the gas tank than cannot be filled. If you force more gas in, you may damage the EVAP system.
- There may be something else that is draining your 12 volt battery, or it is not being charged properly when the car is on. Try one of the inexpensive voltmeters that plug into the 12 volt outlet. With the engine running, you should have about 14.1 volts. With the engine not running (accessory mode), the voltage should be about 12.6 volts for a fully charged battery in good condition. You should be able to go more than four weeks or several months without having the battery drain. If not, the battery is bad or something else is wrong.
Costly Mistakes the RAV4 Owner Could Make
From the thread post, answer #3 is correct that attempting to force more fuel into a gas tank (also known as “topping off”) can damage the EVAP system for these reasons:
- Modern vehicles are equipped with an EVAP system that captures fuel vapors and prevents them from escaping into the air.
- Topping off can push raw gasoline into this system (especially the charcoal canister), which is designed only for vapors—not liquid fuel.
- Once fuel soaks into the charcoal, it can ruin the system and trigger a check engine light—a repair that can cost hundreds of dollars.
From the thread post answers #1 and #2, the technical service bulletin is provided; however, FKHeath appears to be telling the OP not to DIY this TSB fix. In fact, another post further down the thread explains that it can be done by the OP:
You can update the DCM firmware yourself with Tech Stream. I did my old 2020 myself at home. The one caveat is that your RAV4 needs at least one active subscription (SafetyConnect, etc); otherwise, the modem isn’t active to download the firmware. ‒WillRAV4Tacos
The seemingly conflicting answers about the software update are clarified by following WillRAV4Tacos’ update procedure link. The forum poster explains further that this is not a recommended DIY for most car owners:
If you aren’t having any of the issues in the TSB, don’t do this on your own. If you are having these issues, just go to a Toyota dealership. There is a risk of bricking your DCM if you make a mistake doing this on your own. They aren’t cheap, and I’m not responsible if you break your car.
Sound advice for any car owner not well-versed or experienced with car ECM updating, which brings us back to FKHeath’s thread answer #4: “There may be something else that is draining your 12-volt battery.”
Potential Sources of Parasitic Battery Drain Problems
What I like about answer #4 in particular is that it reminds us of the “first things first” approach every DIY mechanic should adopt with any repair.
In the medical world, the adage of “If you hear hoofbeats, think horses―not zebras” is a fair approximation.
In other words, investigating and tackling the simplest source of a problem is often the most effective approach. And, the one recommended for the understandably frustrated OP.
Rather than belaboring a repeat of information about parasitic drain sources in cars and how to diagnose and fix the problem, here are three articles worth reading to explain where the answer to the OP’s battery drain problem may lie:
- We Bought a 2024 Rav4 Prime XSE with the Premium Package, and We Absolutely Love It for Many Reasons, But This Post Is Not About That, It’s Something You Should Know Before Buying a Rav4 Prime
- 3,100 Miles In, I Parked My Hyundai Ioniq in My Garage for 10 Days With 78% Battery, Now It’s Dead And The Dealer Says It Killed The 12V Battery
- I Just Bought a 2015 Highlander off a Lot. However, After Not Driving for a Day or Two I Would Go Out to the Highlander and the Car Would Not Start. That Is When I Saw It…a Tracking Unit Zip Tied Around the Radiator Fan Wiring Harness
It’s Your Turn: If you have had a Toyota RAV4 with a battery drain problem and it was eventually traced to a parasitic draw, please let us know about it in the comments section below.
Timothy Boyer is an automotive reporter based in Cincinnati who currently researches and restores older vehicles, often incorporating engine modifications for improved performance. He also covers modern cars—including EVs—with a focus on DIY mechanics, tool use and selection, and other topics related to automotive repair. Follow Tim on Twitter (@TimBoyerWrites) and Facebook for daily updates and insights on new and used cars and trucks.
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Source: torquenews.com
