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Don’t buy a Subaru Ascent if you car camp or tailgate or…

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Note: This issue is apparently addressed by Subaru Technical Service Bulletin 07-155-19R. If you have an Ascent (or Forester, apparently), have your dealer update your vehicle.

When we owned a boat, we used a 2008 Toyota Sequoia to pull it. The Sequoia is a great truck—it pulled the boat, had tons of room for stuff and people, and rode quite nicely. But it was also incredibly efficient at converting money into gasoline fumes—even when not towing, it only got around 12mpg in town. It's also huge.

With the boat gone, we wanted something smaller, with better mileage, yet with room for seven people and capable of some towing. After a lot of research and a few test drives, we chose to lease a 2019 Subaru Ascent.

Reviews for the Ascent have been positive, with Consumer Reports scoring it at 96. In general, we've been happy with the car…until we took it on its first car camping trip last weekend.

It was there that we learned that Subaru made an incredibly stupid design decision with a vehicle targeted at those who use their vehicles for camping and exploring:

The rear hatch is not designed to be left open.

That's right, you're not supposed to leave the hatch open in an Ascent. Subaru positions themselves as the outdoor enthusiast car company. Their ads are full of people camping, exploring the outdoors, heading off into the great unknown. But with the Ascent (and perhaps other 2019 and newer models as well, based on what I found on the net), if you leave the rear hatch open for an extended period of time, you will kill the battery.

How long is an extended period of time? According to this post, the car draws over four amps with the hatch open, meaning you'll kill the battery within four hours. Yikes!

I'm not sure how long we had our hatch open; it was definitely at least four hours spread over one afternoon/evening and the next morning. And the battery was totally dead—nothing lit up or powered on when I opened the driver's door.

When car camping, an open rear hatch is normal—it's the best way to access the clothing, groceries, and gear in the back of the car. We did this all the time with our Sequoia, and as long as we remembered to turn off the manually-switched light, we never had a problem. But even with the light off in the Ascent, the battery will die.

And it's not just campers that have to worry about this. Dog owners often leave hatches open so their pets can relax in the shade yet covered from the sun or rain or whatever. Tailgaters need the hatch open in order to, well, tailgate. Plus who knows how many other reasons for wanting to leave the hatch open. (And it's not just the hatch—the problem occurs if any door is left open for an extended period of time.)

Why does this happen? Apparently because Subaru engineered the car to wake all the systems when any door opens, and then (this is the insanely stupid part of the design) not include any sort of time out to put those systems back to sleep. You open the hatch, the computers wake up, and then just sit there, talking amongst themselves, getting ready for your imminent departure, but that event never occurs, because you're camping. So the systems keep talking to each other, ad infinitum until the battery dies.

This problem has gotten a fair bit of attention—there are tons of posts about it, and there's even a Facebook group for Ascent owners with open tailgate induced dead batteries.

One enterprising Ascent owner has managed to find a solution that involves pulling and replacing the 14th fuse, and inserting a carabiner in the rear hatch mechanism to fool the car into thinking the latch is closed. Yea, that's what I'd expect to have to do with a Subaru…not!

And it's not like this is a general issue that affects other manufacturers; we were with two Toyotas (one 2013 Sequoia, one 2016 Highlander), neither of which cause their batteries to drain if their hatches are left open.

How can Subaru fix this? They could add an idle timeout, which seems like the best solution. Barring that, they could add a setting to the system that I can access via the touchscreen to enable "camping mode" or "tailgate mode" or whatever.

Hey Subaru, fix this embarrassment, and do so quickly. If we had been aware of this issue before we leased our car, we wouldn't have signed the lease. An although we'll only be one year into a three-year lease, I'll be going to visit Toyota when the new 2020 Highlander Hybrid comes out in February to see if they'll help get us out of our lease.

Not being able to leave the hatch open—without resorting to convoluted workarounds—is a deal breaker for us, because it changes how we use the car. And that's too bad, because it's otherwise an excellent vehicle.

8 thoughts on “Don’t buy a Subaru Ascent if you car camp or tailgate or…”

  1. If yiou need to leave the hatch open, there is a simple work around. Once the hatch is open, push a carabiner into the latch to COMPLETELY latch it. You can tell its latched if the Hatch Open Light goes out. Next, for convenience, take a screwdriver and simply pop open the plastic cover inside the vehicle over the latch. The lame ass manual shows you the small lever that unlatched the door. When you are ready to close up, just flip the lever and open the latch. Then use the FOB to close the hatch like normal . To prove this to my wife who got stuck at a dog training session miles away, I left the hatch open for over 5 hours and it works just fine. Subaru has zero intention to provide any advice or work around for this issue. You can install a simple battery cut off under the hood but it isnt necessary.

    1. Richard: Do you have an Ascent? My understanding is that the Ascent has two issues: One is the latch sensor, which lights the door open light on the dash, and keeps the computer awake. The second is that there's also a door position sensor, and it knows the door is open—and when the door is open, the computer will not sleep. See this video:

      The fix there is that you need to open the hatch, then pull a fuse that will stop the computer from remembering that the door is open, so after its built-in one minute timeout, the computer will go to sleep.

      Basically, having to pull a fuse and do a multi-step door reset process every time you want to leave the hatch open is just a royal PitA.


  2. Should be an easy software fix. But who knows. Still, losing the equity for even a frequent user seems like overkill. The workarounds are a pain, but if you truly leave it open for hours, seems like its adding a few minutes to a camping trip... I have one and love it, good to know info.

  3. Remote on that fuse is a great idea. Makes it even easier. It would be interesting to hear about what benefits leaving the computer on give you.

    1. We bailed on our lease (my wife's car arrived about a year before we were expecting it). However, it seems there may indeed be a fix, though I don't know if it's in the 2020s, or if you'll have to have it done on the 2020s.

      From the Facebook group I linked in the post, I just saw this:

      I recently had the PRG controller replaced under TSB 07-155-19R and measured the battery current with the tailgate open. Right after opening it was 2.2 A. After about 20 min it decreased to 0.2 A and remained there until the last time I checked 3 hrs later. With the (anemic) cargo light on, it was 0.4 A. This didn't change if the key fob was left very near the Ascent.

      This is considerably less than the pre TSB tailgate-open current drain of 4+ A measured by others, and would take well over a week to discharge the battery to 10.5 volts. I imagine you could leave the TG open at least a couple of days without issue. Someone may want to veryify this by leaving the gate open and reading the battery voltage over a few days' time.

      If we still had the car, I'd be calling our dealer asking about TSB 07-155-19R.


        1. We wound up just selling it back to the dealer. There's strong market demand for used Ascents in the Northwest, and while I don't remember the exact cost, the net to use wasn't all that much—maybe two months' lease payments?


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