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Discussion Starter · #1 ·
Hello, everyone.
We're the original owners of a 2020 Ascent, which hasn't had any warranty or reliability issues until today. We got the transmission recall inspection/servicing done 2 weeks ago at the dealership, they told us that a boroscope inspection showed all's well, and they updated the transmission firmware. About 1000 km of driving later, the car started having problems.

While idling in a parking spot, my wife reported hearing a "popcorn noise" from under the hood. The sound has not occurred since. Shortly after we started driving it, from a speed of about 40 km/h (25 mph) the car started to slow down, while engine revs showed about 2000. I pressed down on the accelerator, it had no effect. After 5-10 seconds of this behaviour, the engine's rpms went up, and the car started to accelerate with a jerk. This happened 4 more times over the next 10 minutes of driving, with the rpms indicating between 1000 and 2500 on each occasion.

We were not using cruise control, and neither eyesight nor traction control showed any indication of being involved. The roads were empty of other vehicles, and while there was snow around, the roads weren't slippery at all.

A second problem started to occur at the same time: the car icon that appears in the middle of the instrument panel showed the brakes as being applied when my foot wasn't on the brake pedal. The lights would sometimes flicker off and on over a span of seconds, other times the brake lights would be on continuously over 5 seconds. During these times, the car drove as though no brakes were being applied.

Has anybody seen this issue before? And, can anyone reccommend a good Subaru troubleshooter near Ottawa, ON?

Any advice would be useful at this point: Getting time at a dealership/subaru mechanic is going to be tough, and we've got a long way to drive to get there..
 

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This is something I strongly suggest you take to a dealership - this is not something I'd take to a non-dealership "troubleshooter".

The throttle and brakes are not just two different systems, but one is "drive by wire" (throttle), while the other is mechanical (brakes).
 

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Discussion Starter · #3 ·
This is something I strongly suggest you take to a dealership - this is not something I'd take to a non-dealership "troubleshooter".

The throttle and brakes are not just two different systems, but one is "drive by wire" (throttle), while the other is mechanical (brakes).
To be clear: the brakes are only being applied when I press the brake pedal, it's the brake light indication on the car icon on the instrument panel that's acting odd.
 

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To be clear: the brakes are only being applied when I press the brake pedal, it's the brake light indication on the car icon on the instrument panel that's acting odd.
Sorry, to be clear, that light is driven by the status/position the computer thinks the brake pedal is in. That's a very important data point to be wrong.

Do you two foot drive?

If not, I'd take it in - to a Subaru dealership.
 

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Discussion Starter · #5 ·
Sorry, to be clear, that light is driven by the status/position the computer thinks the brake pedal is in. That's a very important data point to be wrong.

Do you two foot drive?

If not, I'd take it in - to a Subaru dealership.
I do not two foot drive. I wondered if a door mat was rubbing against the pedals (in our snowy climes, door mats can get in the way), but the doormat was properly secured, and wasn't touching the pedals...

Thank you very much for your ideas. They're very helpful.
 

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2022 Ascent Onyx, Ice Silver
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I do not two foot drive. I wondered if a door mat was rubbing against the pedals (in our snowy climes, door mats can get in the way), but the doormat was properly secured, and wasn't touching the pedals...

Thank you very much for your ideas. They're very helpful.
If your car is like mine (2022 Onyx), the "car icon" in the middle screen will only appear when ACC is active. Try switching it "off" with the righthand upper button on the steering wheel and see if the icon disappears as it should. Whether off or on, the red brake lights on the icon should only appear when the brakes are actually applied, either by you or by the ACC system.

I doubt that the quirky behavior is caused by the transmission software update, probably just a coincidence, but anything is possible. This is something that only the dealer is qualified to diagnose and correct, IMHO.
 

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Discussion Starter · #7 ·
Thanks for the ideas, Robert.Mauro & Packard8. I spoke with my dealership, and with a local independent Subaru Mechanic. The independent mechanic is critical of the recall, he thinks that a boroscope inspection of the transmission is useless, he feels the only conclusive test for transmission damage is to drain the transmission fluid & inspect it for metal.

Both mechanic and dealership suspect my transmission is self destructing, and the dealer's asked that my car be towed, not driven, in for servicing. "It might take some time, we're getting a lot of transmission replacements these days". Gulp. The car is 2 yrs, 5 mos old, & has 74000 km.
 

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Thanks for the ideas, Robert.Mauro & Packard8. I spoke with my dealership, and with a local independent Subaru Mechanic. The independent mechanic is critical of the recall, he thinks that a boroscope inspection of the transmission is useless, he feels the only conclusive test for transmission damage is to drain the transmission fluid & inspect it for metal.

Both mechanic and dealership suspect my transmission is self destructing, and the dealer's asked that my car be towed, not driven, in for servicing. "It might take some time, we're getting a lot of transmission replacements these days". Gulp. The car is 2 yrs, 5 mos old, & has 74000 km.
I agree that an inspection of the trans fluid could also be diagnostic. As I understand it, in addition to the visual boroscope, the trans is stress tested while running diagnostics to detect chain slippage. The part that breaks, is the chain guide, which is plastic. The visual inspection will confirm the condition of the chain guide.

The over-revving without acceleration could be the CVT slipping, but the brake lights on the icon is probably a different issue. Will the dealer deliver a loaner when they pick up your car? I hope so, you might ask. That (or a rental) is a standard policy here in the states. Keep us posted!
 

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s I understand it, in addition to the visual boroscope, the trans is stress tested while running diagnostics to detect chain slippage. The part that breaks, is the chain guide, which is plastic. The visual inspection will confirm the condition of the chain guide.
^^ This. The borescope inspection is necessary for this reason. The "transmission" isn't breaking from the flawed software, per se, but the chain guide is and that results in further damage. I do agree that fluid analysis is often an additional data point that can be helpful with diagnosis, of course.
 

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2019 Subaru Ascent Limited 2010 Subaru Legacy GT limited
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Thanks for the ideas, Robert.Mauro & Packard8. I spoke with my dealership, and with a local independent Subaru Mechanic. The independent mechanic is critical of the recall, he thinks that a boroscope inspection of the transmission is useless, he feels the only conclusive test for transmission damage is to drain the transmission fluid & inspect it for metal.

Both mechanic and dealership suspect my transmission is self destructing, and the dealer's asked that my car be towed, not driven, in for servicing. "It might take some time, we're getting a lot of transmission replacements these days". Gulp. The car is 2 yrs, 5 mos old, & has 74000 km.
As I recall the fluid is drained for the inspection, as the drain and fill plugs are the only way to boroscope the TR690. Not only that but the TCM records any slip events, this cannot be erased or reset, so the data will indicate when slip has occurred in relation to the chain and pulleys.
 

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Discussion Starter · #11 ·
Our Subaru dealer: Ogilvie Subaru says there's no need to look at the transmission. They found a faulty brake light switch, so the troubleshooting stopped there. They say it's a non-warranty repair, I'm just worried that after we wait 3 days to get the new switch put in we'll still have a transmission problem.
 

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Fortunately, nothing you described is related to the transmission, and your mechanic friend has no idea what the inspection shows. This isn't a belt driven CVT by Nissan or others.

The boroscope literally shows the massive variators and chains, allowing visually detecting the scoring that would lead to metal in the fluid.

Because there's literally zero gears in the TR690 that engage or disengage, the variators & chain are virtually always the single source of metal flakes in a TR690.
 
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