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Discussion Starter · #1 ·
Long time lurker, first time poster here on the forum. I'm the owner of a 2020 Forester Limited, my first ever Subaru and first ever new car! I really have enjoyed the Forester except for one issue that has been covered as a know design flaw here on the forum. I like to leave the tailgate open for extended periods of time when doing outdoor activities, I know, crazy stuff... I do the workaround of inserting a carabiner into the latch, manually lowering the hatch until the latch motor engages, then opening the hatch manually back up to disable the Power Rear Gate control module. Yes this works, but seems a little ridiculous on a brand new vehicle. Without this workaround, I measured the continuous 4 amp power draw which has left me with a dead battery several times.

It seems Subaru may possibly be listening to all of the owner complaints about the issue. I stumbled across this revised TSB on the Ascent forum with owners having a similar issue that also pertains to 2019-20 Foresters. It appears the rear gate module is now on revision #6 for the Forester and it mentions preventing excessive "dark draw", but doesn’t really get specific about whether is solves the problem with the hatch being left open.

Has anyone had this latest PRG module installed on their 2019-2020 Forester? If someone out there has this latest PRG module or has a Forester with a VIN after LH477261 and could measure the amp draw when the hatch is left open, this may finally be a more permanent solution.

TSB NUMBER: 07-155-19R DATE: 06/12/2019 REVISED: 03/16/2020

APPLICABILITY: 2019-20MY Forester 2019MY Ascent SUBJECT: Power Rear Gate (PRG) Control Module- Design Change

INTRODUCTION: This bulletin announces a design change made to the PRG control module. This change is in response to a limited number of customer concerns regarding the rear gate not opening when operating the gate switch or dashboard switch on the vehicle or the button on the key fob. In addition to ensuring proper PRG system operation, the new logic also optimizes the PRG communication function. The change will prevent excessive dark draw which may over time, cause a low battery condition.

PRODUCTION CHANGE INFORMATION: The new PRG control modules were incorporated into production as follows:
  • Forester: Starting with VIN LH477261
  • Ascent: Start of 2020MY production
PART INFORMATION:

ECU-POWER REAR GATE:
  • 63350SJ006 for 2019-2020MY Forester
  • 63350XC10B 2019MY Ascent
 

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That would be nice to fix tailgate issues. One among many for me. Often times mine will not open from key fob inside or outside button. It also tends to stop in dd positions even without memory button engaged. Just one of very many problems I've had with my new Subaru. I started noticing many problems in the first 4000 miles and it got way worse towards 30k miles. I sincerely hope you have better luck than me because this is a lemon in my experience with new cars. Oh beware of the cheapo batteries. They leak and gas sulfuric acid that rapidly eats the bracket/terminals or anything nearby. My first battery died in months leaving a huge mess of corrosion that dealer didn't even bother to clean up. It's been one sad thing after another for me. Definitely not like old Subarus were, they were good fair priced cars years ago. Now I pay over $40k for a new car with nightmare of problems. My $33k BMW 1 series battery lasted 6 years and never leaked a single drop or ever went dead before selling it. But Subaru puts the cheapest oldest open top battery into the most expensive forester made today?
 

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Sounds really scary they have to provide a new hardware revision instead of a firmware upgrade...
 

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I'm definitely not too impressed with the factory battery either. I've killed it with the hatch open in as little as 4 hours when I installed my EcoHitch. At 4A draw X 4 hours = 16Ah. I believe the factory battery is rated at 60Ah from memory, so it should still have enough power to crank the engine at that point. Even when fully charged, the factory battery just doesn't feel overly powerful cranking the engine. I'll be replacing it with an AGM battery when this one dies.
 

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Oh, that's interesting. That might explain why my battery died recently, even though nothing was left on or open. I'm having hatch issues with the sensor kicking in intermittently.
 

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Did you sell your 2018? :)

TSB is for 2019-2020 MY.
2018's have the same junk battery as a 2020. Regardless of TSB in 2019-2020 the battery will still die with hatch open for a few hours... It happened to me. It also happens to my friend who purchased a 2019 against my recommendation. Its really not a great car for outdoors and mountains in my experience. Much better options out there.. Trying my best to keep it running good though. Best I can do for now. Next is a new A/C compressor. I got new vacuum pump and almost ready.
 

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Sahuarita, AZ 2018 Forester Limited
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2018's have the same junk battery as a 2020.
Based upon postings on this forum, it appears that battery complaints have increased significantly in the 2019-2020 model years. Perhaps more parasitic drain with the new ones or the effects of repeated auto stop/starts.
 

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Discussion Starter · #10 ·
Attached is a picture of how I am measuring the current draw on my 2020 Forester. I am using an ammeter clamped around the positive cables right off the battery. I am not sure what PRG module revision I have since I haven't had time to tear things apart to get to it, but it is not the latest one as my VIN falls before the one listed in the new TSB.

For the measurement in the picture, the hatch is open, interior lights (led) are on, subispeed led light in the bottom of the hatch is on. Measuring 4.38 amps.

The current does drop off a little after the lights all turn off, but it still remains around 4 amps.

Parasitic drain does not appear to be a huge problem. I am measuring somewhere around 50 milliamps during "sleep" mode. My ammeter is not that high end to get a very accurate measurement at that low of a current, but the vehicle does go to a pretty low power state. The vehicle seems to enter "sleep" about 1 minute after all doors and hatch are closed.

I do agree with several other discussions here on the forum that Subaru used a lower quality battery than they should have, especially with the demands of auto start/stop.

Hatch_amps.jpg
 

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Those are pretty much the same numbers I measured here ('19+) - 2019 - Drained my battery! How?. I had a clamp meter like you, but it lacked enough resolution, so I measured it in-line with an ammeter that could read milliamps.

2018's have the same junk battery as a 2020.
That is incorrect; 2019-2020 Foresters have a different junk battery. :) Cars with start/stop use either an EFB type battery (Enhanced Flooded Battery) or AGM to handle the increased cycling. The 2019, and presumably 2020, have Q85 batteries, which are EFB.

I'll likely put an AGM in when the current battery dies.
 

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Long time lurker, first time poster here on the forum. I'm the owner of a 2020 Forester Limited, my first ever Subaru and first ever new car! I really have enjoyed the Forester except for one issue that has been covered as a know design flaw here on the forum. I like to leave the tailgate open for extended periods of time when doing outdoor activities, I know, crazy stuff... I do the workaround of inserting a carabiner into the latch, manually lowering the hatch until the latch motor engages, then opening the hatch manually back up to disable the Power Rear Gate control module. Yes this works, but seems a little ridiculous on a brand new vehicle. Without this workaround, I measured the continuous 4 amp power draw which has left me with a dead battery several times.

It seems Subaru may possibly be listening to all of the owner complaints about the issue. I stumbled across this revised TSB on the Ascent forum with owners having a similar issue that also pertains to 2019-20 Foresters. It appears the rear gate module is now on revision #6 for the Forester and it mentions preventing excessive "dark draw", but doesn’t really get specific about whether is solves the problem with the hatch being left open.

Has anyone had this latest PRG module installed on their 2019-2020 Forester? If someone out there has this latest PRG module or has a Forester with a VIN after LH477261 and could measure the amp draw when the hatch is left open, this may finally be a more permanent solution.
Congrats second for me I couldn't resist 0.99%!
 

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I scanned the barcode on my latest forester xt battery replacement which was made 10/2019. Leaking and corroding everything nearby in three months. Its apparently just a cheap rebranded open top wet cell. Basically a 30 dollar battery in china sold for 80 bucks in Houston. I'm going to just make a battery from "Headway" Lifepo4 15amp cells. I've done larger builds for my 52 ft sailboat with the same cells. Excellent performance! Kept me powered through a hurricane with minimal generator recharging. It's funny too how the battery will have way more juice in the same space and much wider operation temp range. Plus you can leave it parked at airport for 3 months and it will start no problem. Those Subaru people ripped me off!
 

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Interested in your Lifepo4 project. Keep us posted. Subaru did us bad by not shutting off the interior lights after a period (10min?) Every other recent car does it. My 2008 suburban does it. Simple software change. Why generate such negative feedback over simple fix. Only 750 mi on my 2019 Forester, wife has had to call tow 2x and me 3x. Hey Subaru, does it make sense to ignore issue.
 

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Sahuarita, AZ 2018 Forester Limited
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Subaru did us bad by not shutting off the interior lights after a period (10min?) Every other recent car does it. My 2008 suburban does it.
Mt 2018 Limited has what Subaru calls a Battery Drainage Prevention Function (page 2-8 of the owners manual). It turns off the map lights, dome light, cargo light and ignition switch light after 20 minutes of leaving a door or tailgate ajar.
 

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Well should not be a so difficult feature. After 10-20 minutes shut down all the interior lights. After max 45s shut down the whole CAN bus network, the instrument cluster and leave there only a small led on indicating “there is a door/trunk/bonnet open”.
 

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Those are pretty much the same numbers I measured here ('19+) - 2019 - Drained my battery! How?. I had a clamp meter like you, but it lacked enough resolution, so I measured it in-line with an ammeter that could read milliamps.


That is incorrect; 2019-2020 Foresters have a different junk battery. :) Cars with start/stop use either an EFB type battery (Enhanced Flooded Battery) or AGM to handle the increased cycling. The 2019, and presumably 2020, have Q85 batteries, which are EFB.

I'll likely put an AGM in when the current battery dies.
I’m thinking why wait, on my end. I’m going to be hardwiring a dash cam and despite my Subie being less than a month old and under 1k miles I might just swap out the battery this weekend. Any reason not to other than cost efficiencies is the question.
 

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Long time lurker, first time poster here on the forum. I'm the owner of a 2020 Forester Limited, my first ever Subaru and first ever new car! I really have enjoyed the Forester except for one issue that has been covered as a know design flaw here on the forum. I like to leave the tailgate open for extended periods of time when doing outdoor activities, I know, crazy stuff... I do the workaround of inserting a carabiner into the latch, manually lowering the hatch until the latch motor engages, then opening the hatch manually back up to disable the Power Rear Gate control module. Yes this works, but seems a little ridiculous on a brand new vehicle. Without this workaround, I measured the continuous 4 amp power draw which has left me with a dead battery several times.

It seems Subaru may possibly be listening to all of the owner complaints about the issue. I stumbled across this revised TSB on the Ascent forum with owners having a similar issue that also pertains to 2019-20 Foresters. It appears the rear gate module is now on revision #6 for the Forester and it mentions preventing excessive "dark draw", but doesn’t really get specific about whether is solves the problem with the hatch being left open.

Has anyone had this latest PRG module installed on their 2019-2020 Forester? If someone out there has this latest PRG module or has a Forester with a VIN after LH477261 and could measure the amp draw when the hatch is left open, this may finally be a more permanent solution.
 

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The TSB refers to Forrester starting with VIN LH477261. My '20 Forrester bought last November is VIN LH408492. Does that mean my car has the bad module before they fixed it? I had planned on leaving the rear gate open while camping this summer. Called the dealership and they said they couldn't do anything about it until it became an issue. That would mean they want me to be stranded with a dead car in the mountains without cell service before they would replace my module? Who can I talk to at Subaru about this?
 
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