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Discussion Starter · #1 ·
Some times when I put the car in paddle shifting, the right paddle which shifts up doesn't work. Instead of shifting to a higher gear, it drops a gear. So essentially, both paddles down shift. If I restart the car it will fix the problem 85% of the time. Anyone else experience this? Don't use the paddle shifting that often and too lazy to bring to the dealer.
 

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Known issue and there are a bunch of threads accessible through search. The up shift and down shift are controlled by a pulse of voltage stemming from pull of the paddle. When the up shift voltage is too low, the computer interprets the pulse as a down shift.

Others have had decent luck with the dealer replacing the paddles.

I've never experienced the issue in this platform but have in my Audi TTS. I had to change the way I pulled the paddle to ensure that the "button" behind the paddle was being hit with force eliminating a low voltage pull. AKA.. pull the paddle a little bit more deliberately with a little greater force.
 
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Discussion Starter · #4 ·
Appreciate the help. I assume this is a software issue and nothing to do with the actual transmission so i'm not doing more damage by doing nothing.
 

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2020 Challenger Hellraisin Scat Pack.
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Appreciate the help. I assume this is a software issue and nothing to do with the actual transmission so i'm not doing more damage by doing nothing.
My Hellcat manifests this behavior. As an aside I have found how I pull the paddle back doesn't seem to have any affect on whether the behavior happens or not. It does appear to be a bit related to temperature, ambient temperature. During the "worst" of winter here it seemed like the behavior was quite rare.

More recently as it has become a bit warmer the behavior has become more common.

One possible risk of damage if not to the transmission to the engine is under hard acceleration when I go to up shift near or at red line and the up paddle shifter screws up and signals a down shift can this result in a down shift that might be the same as a "money" shift with a manual transmission?

That is could the spurious downshift from the up shift paddle somehow make it past the whatever "filter" there is to prevent a downshift that would result in an engine over speed event?

There is another issue and that is occasionally the down shift has occurred when I wanted to shift from 2nd to 3rd but instead drops the gear to 1st gear. This is a rather large and abrupt change in gears and while the engine doesn't experience an over speed event the down shift upsets the car some. In a marginal traction condition an inappropriate down shift when an up shift was expected could have the car losing traction/the driver losing control.

Last time I checked, several months ago, I was told there was as yet nothing from the factory on this problem. I have not had a chance to visit a dealer to ask for an update on this subject.
 

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Some times when I put the car in paddle shifting, the right paddle which shifts up doesn't work. Instead of shifting to a higher gear, it drops a gear. So essentially, both paddles down shift. If I restart the car it will fix the problem 85% of the time. Anyone else experience this? Don't use the paddle shifting that often and too lazy to bring to the dealer.
dealer replaced both paddle shifters, and updated the TCM software, so far so good. I use the paddle shifters 99% of the time.
 

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The paddles are only for going up to redline on the money shifts!...If you use the paddles to putz around It’ll do the downshifting garbage
 

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The paddles are only for going up to redline on the money shifts!...If you use the paddles to putz around It’ll do the downshifting garbage
Not quite sure what you are trying to say. I feared that taking the engine up to red line then pulling the +paddle could possibly cause a down shift that would over rev the engine. While operating normally the engine (or transmission) controller will not allow a downshift to happen -- at least when the downshift is from the -paddle or the shift lever -- if this would result in an over rev of the engine I had no desire to test if this was the case in the event a +paddle caused a downshift.

At any rate I got this "fixed".

Shop foreman found my 2018 Challenger Hellcat due for two flash updates. One for the PCM the other for the TCM. He had a tech apply these. Subsequent testing by me over time found the behavior no longer present.

Here is some more info on the then current flash part #s and the new part #s:

The following info is from my 2018 Challenger Hellcat.


PCM current part number: 05035946AE
PCM new part number: 05035946AG

Yes, just the last letter is different.

TCM current part number: 05035529AC
TCM new part number: 05035529AD

Just the last letter is different.

Oh, the above was as of August 1, 2019. It is possible there might be a more recent and thus different part number PCM or TCM updates.

Besides recognizing the car needed two new flash updates the shop foreman also found a couple of low voltage errors logged. There was no CEL the errors were logged as part of the engine controller's "secret" diagnostics is my WAG.

What I had attributed to cold temperature was in fact caused by low battery voltage caused the the lack of sufficient use of the car in cold weather. While snow was not a concern where I lived there was rain and people can't drive in the rain in CA so I left the Hellcat at home most of the time.

After the flash updates I vowed to drive the car more often to avoid the battery getting too low. While the engine fired right up I believe the voltage level dipped too low which glitched some electronics. (As an aside when I wrote car test software I encountered this and had to modify the low voltage detection algorithm to avoid flagging a false low power event on a glitch.)

As long as I drive my Hellcat frequently and for some time the low voltage glitching appears to be a thing of the past. One sign the power is getting low and the glitching is occurring is when I call up Performance Pages the app fails to load. Even turning off the engine then restarting it doesn't "fix" Performance Pages. I have to drive the car some time. This PP failure to load happened the other day and only after I drove the car a good distance the next day when I went to use it did the PP app load ok after engine start.
 

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2020 Challenger Hellcat Redeye Wide Body
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Ya the modern day vehicles are super sensitive to voltage flux. They will do some weird things if left to fend for themselves.
 

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The only thing I know for sure is that’s the way of it with mine, I’ve had it do the downshifting thing when I would try to drive like a sane person
 

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The only thing I know for sure is that’s the way of it with mine, I’ve had it do the downshifting thing when I would try to drive like a sane person
Oh I'm not arguing that. That is when I noticed it. I had I'm sure driven the car a bit aggressively and used the +paddle and had not experienced the spurious downshift. But when I started experiencing this behavior when I was driving "like a sane person" just to be "safe" I made it a point to never ever drive the car aggressively and use the +paddle to upshift at or near red line.
 

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Nail on the head Rock!...you’re correct In that it’s a voltage thing and I get the danger aspect risking pink mist, hand cuffs and calling a tow truck but at some point the driver just has to realize “WTH am I doing putzing around in this awesome machine”..might as well shave a little carbon off the valves and get some oil up on that cam
 

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Nail on the head Rock!...you’re correct In that it’s a voltage thing and I get the danger aspect risking pink mist, hand cuffs and calling a tow truck but at some point the driver just has to realize “WTH am I doing putzing around in this awesome machine”..might as well shave a little carbon off the valves and get some oil up on that cam
Well, the car gets a bit of carbon shaving usage once in a while. I am more inclined to shift closer to red line using the +paddle now than before the shop foreman applied the updates and my experience after found the spurious downshift behavior a thing of the past.

But for maximum acceleration I leave the transmission in D. I can't time my shifting to the RPMs nearly as good and as consistently good as the PCM/TCM can.

So when in manual mode if I use the +paddle it is for generally more sedate driving although I do like to rev the enginei a bit higher than it would otherwise rev if left in D. If I engage in harder acceleration I may still use the +paddle (or the lever, and I never once had this result in a spurious downshift) but I up shift early to avoid banging up against the rev limiter.
 

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dealer replaced both paddle shifters, and updated the TCM software, so far so good. I use the paddle shifters 99% of the time.
My 2016 is having the same issues now, I know its been over a year since you posted this. Have you still not had any issues after the replacement paddles and the TCM re-flash. The Dealer replace my entire shifter thinking that was the problem, worked for awhile now its back.
 

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My 2016 is having the same issues now, I know its been over a year since you posted this. Have you still not had any issues after the replacement paddles and the TCM re-flash. The Dealer replace my entire shifter thinking that was the problem, worked for awhile now its back.
t never happened again after the replacement and flash for over 4,000 miles, But I sold it after that.
 

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Rockster, great posts. I learn something almost every time I read this Forum. My Challenger HC RE WB has done the same thing, with the paddles and loading Performance Pages. I've found that after starting I have to wait a few minutes to attempt to load Performance Pages or they won't load, unless I shut the car down for several minutes, restart, and then wait again. I love the car, but having to get my oil temp via the internet is a pain in the ass.
 
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