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Discussion Starter · #1 ·
Hi, I'm sorry, I did a search and it seems there are so many discussions. I'm one in the dead battery club when the kids brought the groceries in and forgot to shut the tailgate. It seems someone mentioned a possible fix under warranty to the problem. We aren't DIY people and this isn't just for intentionally leaving it open, I need to know if I accidentally leave it open with a new battery that it won't be left dead. We would sure also love to leave it open while camping but there are so many "this should work" things that I don't want to accidentally get wrong and be stuck.
If someone can please just tell me what to ask my dealer for if there are truly updates and fixes for this problem, that would be really great. Thanks so much! Appreciate this forum. We absolutely love our dear Sueberry for everything else.
We have an early 2020 model if that makes a difference.
 

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Buying a new quality AGM battery and replacing the factory Subaru battery will resolve the battery issue. The general consensus is that the factory battery isn’t well suited for the electrical draws from the Ascent.
 

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A better battery will help, but the tailgate draws ~4A/hr indefinitely. That'll totally drain a group 35 battery in about 15 hrs. It'll probably get it below starting level after 10 hrs, or maybe less.
 

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Mention TSB 07-155-19R to your dealer. If they can verify your symptoms: rear liftgate not opening when operating the gate switch or dashboard switch, and/or excessive ‘dark draw’ on your battery they can install a replacement ecu 63350XC10B per the TSB.
I, however, wasn’t successful at the dealer but I’ve never had a dead battery and didn’t push the issue with them. So I use the carabiner method for now 🤷‍♂️
 

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Discussion Starter · #5 ·
Thank you. I'm disappointed. I thought I had seen a real warranty fix. I guess we will have to hope they can verify the things that xydadx3 has mentioned. Thank you!
 

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Thank you. I'm disappointed. I thought I had seen a real warranty fix. I guess we will have to hope they can verify the things that xydadx3 has mentioned. Thank you!
First, the weak OEM battery has to go. Call SOA and request a new battery to replace the OEM which has a poor reserve capacity. They'll either let you buy your own and reimburse you or send you back to the dealer for a free replacement. Or simply take matters into your own hands, go to Walmart and buy an EverStart MAXX-35N (North) Battery for around $95. This battery is nearly as highly rated as an Optima AGM battery costing 3 times as much.

This alone should solve your problem, it did for me.

If not, then do as suggested above and request TSB 07-155-19R from your dealer. This too should help.

If you do these free fixes you should be fine unless you choose to leave the liftgate open for hours on end. If you think that you may do that, then purchase a lithium backup starter battery just in case you ever get stuck.
 

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I haven't heard anywhere that TSB 07-155-19R does indeed fix the excessive gate-open current. The TSB says something about dark draw but IDK what that means. If someone has had the TSB done and can check, that would be great.
 

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i don't know ... on 2019 i kept it open over 9 hours(testing) and car still started battery was down 11.91 (from 12.47)
all my interior lights changed to LED
on 2020 power save mode activates in 20 minutes
 

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I haven't heard anywhere that TSB 07-155-19R does indeed fix the excessive gate-open current. The TSB says something about dark draw but IDK what that means. If someone has had the TSB done and can check, that would be great.
Usually it is called a parasitic draw as it doesn't shutoff slowly drains the battery.
 

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I understand the words, but not specifically if they mean that the open tg draw is substantially less than the previous 4A. To really know, it needs to be measured and verified by somebody who has had the TSB performed.
 

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I posted today (8/7) in that thread that I 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 for the 3 hrs I measured it. This is a lot less than the 4+ A others measured before the TSB. I believe this should allow leaving the TG open for several days without issue.
 

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Merope: Thanks for your new post. My dealer has been working with me to fix the problem for TWO years now, but he had previously NOT volunteered to replace the PRG under that TSB because it was to solve a different problem (RG not opening). But, I immediately copied your forum post in an email to my dealer just now, asking him to replace the PRG under warranty in consideration of your lower-draw results, and he AGREED to do so. Thanks again for your post. I'll report my results after I get the new PRG.
 

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I’m going to ask my dealer to replace the PRG controller as well. You should know that if asked, SOA will pay an amount equal to an Odyssey battery replacement if you DIY. That’s exactly what I did.
 

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I just did some research on this and discovered the TSB has been revised three times.

06/12/19 - 07-155-19 - Initial release - 2019MY Forester
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. This
condition is also accompanied by three short beeps. Logic changes have been incorporated into the
new module to ensure proper operation of the PRG system.

07/09/19 - 07-155-19R - Added 2019MY Ascent

03/16/20 - 07-155-19R - Added 2020MY Forester - Added additional information regarding dark draw

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.

05/15/20 - 07-155-19R - Added 2020MY Ascent

BobaruCA, it looks like the information in the 03/16 update did include mention of a dark draw causing a low battery condition. It may be possible that your dealer wasn't aware of the revised description. It's also possible that the details are sort of vague and don't really specify if it resolved the exact issue.
 

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IMO, the wording of the TSB "introduction" is ambiguous on the subject. It adds at the end, "...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." Had they added "with the tail gate open," it wouldn't be.

At any rate, I had ~three occurances where the TG hung and had to be reset by holding the TG button for 10 seconds. That's the main point of the TSB and that's what I went to the dealer with. When I called to set up the service appointment, I explained there was a TSB for the problem and a part would be needed. They said they wouldn't check inventory or order the part and that the service tech would have to make that determination when I brought the car in for the appointment, which was two weeks out. When I brought it in, they didn't want to hear the TSB number, only the complaint. They then ordered the part and I had to come in a week later to get the work done. Silly game.

My theory here is that Subaru instructs dealers that customers have to come in with the complaint, not the TSB number, to try to prevent customers from looking up all that might pertain to their vehicle and insisting they be done. On the dealer's part, Subaru compensates them for the work so I don't think they have any reason not to want to do it.
 

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Update:
I just got the PRG module that controls the rear lift gate replaced under TSB 07-155-19R. They tested the unit and found that the current draw on my PRG is 1.23 amps initially, dropping to 0.088 amps after 10 minutes. Spec is 0.070 amps. After replacement of the module the current draw dropped to 0.033 amps.

Combined with my upgraded Odyssey battery (which Subaru paid for in full and I installed myself), I hope this puts an end to the dead battery situation once and for all.

5702
 

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^^^??? Odd. The old problematic controller drew ~ 4A and never decreased below that, which is what drained the battery overnight. My new cotroller takes 20min to drop below 1A, as do others. Your original controller at 0.088 would take weeks to drain the battery. The doc you pasted says it dropped to 0.033 after disconnecting the controller, not after it was replaced, and recommends replacing it. It doesn't say that it was. If it was indeed replaced, what did it measure after replacement?
 

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Yeah I noticed that they didn't measure the draw after replacing the PRG. Can someone give me the details/instructions on how to measure the current draw after the 10-20 minutes? I would like to check that. In either case since Subaru has issued a new PRG controller, I figured having the most current version would be a good thing.

^^^??? Odd. The old problematic controller drew ~ 4A and never decreased below that, which is what drained the battery overnight. My new cotroller takes 20min to drop below 1A, as do others. Your original controller at 0.088 would take weeks to drain the battery. The doc you pasted says it dropped to 0.033 after disconnecting the controller, not after it was replaced, and recommends replacing it. It doesn't say that it was. If it was indeed replaced, what did it measure after replacement?
 

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I take mine in to get the new module on Monday. I tested the present module, it drew 4.3amps with reargate open and light on. It dropped to 3.77 after 20 minutes and stayed at that for the next 3 hours. I had the fob with me when I approached and reading went up to 4.32 again. I closed the reargate and after about 7 minutes things shut down and draw was .28 amps. When I locked the car it dropped to .20amp.

Use a decent VOmeter that reads DC volt/amp draw. Open rear gate, shut all other doors. Make sure the FOBs are out of range of the car. Remove the negative cable on battery, connect your VOM set for a 10amp DC reading, some meters you may need to move the black lead to the other connector on meter. Use a little clamp to hold the red lead to battery terminal and the black lead to negative battery cable, current will then flow thru the meter and give you a reading. If it's a negative number reverse the leads. Should start out with reargate lights on at just over 4amps, after the lights go off, load will drop to 3.8-3.9 amps. Like I said above I let mine sit for 3 hours and would check on it every once in a while, draw never changed, until I approached with a fob.

I will rerun the test after I get home on Monday and post results here.
 
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