2011 SS Automatic - Manually Downshifts on its own when stopping. - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Tiberious · 08-26-2015, 04:20 PM

Hey guys, got a problem I can't seem to find much about.....

The dealer talked to me like I was an idiot and inferred that I was accidently hitting the paddle shifter, which is not the case.

What’s happening is that from time to time, during deceleration generally, the car drops gears as if manually down-shifting, resulting in a surge forward. As this is while I’m trying to stop the car, this is a real problem and has nearly caused me to hit the car ahead of me at the stop. I have noticed twice that the display shows M2, which supports the manual down-shifting theory, but I am most definitely not doing it. One of these days an accident will occur, so I’m doing what I can to find the problem and get it resolved. The dealership wants to drive it, but as it’s about a one in 500 occurrence (thereabouts) it’d be pointless to do this. I asked them to check the computer, they report no issues logged.

Any ideas?

Thanks,

Tib

ucHuskies · 08-26-2015, 06:23 PM

I've never had something like this happen but I read a post a while back from a vendor here, CFD, that spoke about the wiring behind the tap shifters. Basically they are a circuit that have resistors of a certain value and when the button is pushed the computer knows to switch gears based on the value of the resistor. If this circuitry failed, I could see your car shifting erratically -- and I doubt it would show up as an error log. I'd have the dealer check to make sure the wiring was all good.

http://www.camaro5.com/forums/showpo...5&postcount=88

VTSummit · 08-26-2015, 06:30 PM

Maybe pop the manual buttons off for a while... any chance there's debris behind a button?
I'm just thinking if the buttons were off and it still did it, then there's obviously a problem in the electrical portion of the switch. I would imagine your car is out of warranty and the replacement part is probably cheap to swap out on the downshift side of the wheel.

CFD · 08-26-2015, 07:31 PM

Quote:

Originally Posted by ucHuskies

I've never had something like this happen but I read a post a while back from a vendor here, CFD, that spoke about the wiring behind the tap shifters. Basically they are a circuit that have resistors of a certain value and when the button is pushed the computer knows to switch gears based on the value of the resistor. If this circuitry failed, I could see your car shifting erratically -- and I doubt it would show up as an error log. I'd have the dealer check to make sure the wiring was all good.

http://www.camaro5.com/forums/showpo...5&postcount=88

This is correct, also if a resistor or connection to the resistor is faulty it will result in a downshift. I'm sure there may be other things such as in the TCM that could cause it but if it was me, I'd be paying attention to the switches. They can be affected by heat, humidity, vibration etc. so it may not be something you can see or test for where it is intermittent, disconnecting the switches would be the easiest to do and if it is a switch, you eliminated the problem until you can get them replaced.

Rock-It Man · 08-26-2015, 07:33 PM

Are you in S mode when the car decides on its own to go to M?

JSure83 · 08-31-2015, 02:15 AM

This happens on my 04 Malibu Classic when I'm slowing down to a stop. It's almost like driving a stick and just moving back to 3rd/2nd to help slow down a reduce wear on the brakes. Now granted, I'm selling that car and driving my LS1, but all this to say that my other Chevy car which was an automatic did behave this way. However, it wasn't bumping forward but actually helping slow the car down. Hope that helps.

jshaf · 08-31-2015, 06:30 PM

only time I notice this is when I accidently have it in S mode, and of course not using paddles.

trodecke · 08-31-2015, 10:19 PM

I haven't seen that exact issue but I do experience something very much like that. When I'm slowing to a stop, usually as the car is dropping below 10 mph, I feel a definite "bump", like it's making a hard shift from 3rd to 2nd. I don't recall seeing the M2 in the DIC but I do feel the surge. For me though it's every single time.

bork_bork · 09-01-2015, 04:42 AM

This has happened to me when I have it in sport mode and not manually shifting. Its only happened a couple times though

MrChrisLS3 · 09-01-2015, 01:12 PM

From the description, it sounds like the trans is getting hung up between gears. Automatic transmissions do downshift during deceleration to keep the engine rpms consistent with speed. However, it sounds here like it's taking too long between gears, in other words, like it is riding in neutral too long than slipping into gear, causing the "surging" when coming to a stop.

kevint · 09-01-2015, 01:27 PM

My drop into first at ~6mph is usually pretty obvious.

ClawSS · 09-01-2015, 01:34 PM

Are you in "D" when this is happening? Do you have an aftermarket tune installed?

kmarshall2121 · 09-01-2015, 03:37 PM

I believe its suppose to do this. Mine 'downshifts' on its own when i am de-celerating, or starting to slow down like coming down out of a grade.

Tiberious · 09-03-2015, 05:15 PM

Thanks all. No, I'm in D and I've lightly tapped the shifter to see if there's some way it could just be oversensitive or some physical glitch, no dice. The problem isn't so much that it downshifts, that's to be expected, it's definitely not normal though as it shifts in such a way as the car surges forward just as I'm stopping. Nothing normal about that. Also the fact that it says M1 when I am not manually shifting should make it clear that it's not a normal downshift. No aftermarket tuning, still under extended warranty. I think MrChris has it about right, but without getting the dealer to be able to repeat the problem, I'm not getting any support. My brother in law and nephew both work at GM and are looking into the issue from that end. I can't imagine that I'm the only person with this problem though. Thanks all for the feedback, while I'm disappointed that nobody knows for sure what's going on, I'm glad none of you have the same problem!

Tib

08-26-2015, 04:20 PM	#1
Tiberious Old '71 Owner Drives: 11 Camaro Vert;97 Malibu;03 Venture Join Date: Apr 2010 Location: Tacoma, WA Posts: 396	2011 SS Automatic - Manually Downshifts on its own when stopping. Hey guys, got a problem I can't seem to find much about..... The dealer talked to me like I was an idiot and inferred that I was accidently hitting the paddle shifter, which is not the case. What’s happening is that from time to time, during deceleration generally, the car drops gears as if manually down-shifting, resulting in a surge forward. As this is while I’m trying to stop the car, this is a real problem and has nearly caused me to hit the car ahead of me at the stop. I have noticed twice that the display shows M2, which supports the manual down-shifting theory, but I am most definitely not doing it. One of these days an accident will occur, so I’m doing what I can to find the problem and get it resolved. The dealership wants to drive it, but as it’s about a one in 500 occurrence (thereabouts) it’d be pointless to do this. I asked them to check the computer, they report no issues logged. Any ideas? Thanks, Tib __________________ Peace was my profession...

08-26-2015, 06:23 PM	#2
ucHuskies Drives: 2014 SS/RS Blue Ray Join Date: Mar 2015 Location: Long Island, NY Posts: 67	I've never had something like this happen but I read a post a while back from a vendor here, CFD, that spoke about the wiring behind the tap shifters. Basically they are a circuit that have resistors of a certain value and when the button is pushed the computer knows to switch gears based on the value of the resistor. If this circuitry failed, I could see your car shifting erratically -- and I doubt it would show up as an error log. I'd have the dealer check to make sure the wiring was all good. http://www.camaro5.com/forums/showpo...5&postcount=88 __________________ 2014 1SS/RS L99 Blue Ray Metallic Patrick G Tune \| K&N High Flow \| SOLO Axle Back w/ J-Pipes \| JEGS X-Pipe Resonator Delete

08-26-2015, 06:30 PM	#3
VTSummit Consistently inconsistent Drives: 2015 2LT Summit White Join Date: May 2015 Location: United States Posts: 1,364	Maybe pop the manual buttons off for a while... any chance there's debris behind a button? I'm just thinking if the buttons were off and it still did it, then there's obviously a problem in the electrical portion of the switch. I would imagine your car is out of warranty and the replacement part is probably cheap to swap out on the downshift side of the wheel. __________________ Thanks to MRR, I have some SWEET wheels! Thank you! 2015 2LT Ported TB, Ported intake, JACFAB intake spacer, Borla exhaust, IPF 91 tune, Complete 1/LE suspension, Brembo brakes, Goodridge lines, Elite catch can, CAI with Thermo-wrap, 275/40-20 x 10's all around, Z/28 spoiler, GM splitter, Alpine/Polk stereo with AudiControl interface.

08-31-2015, 06:30 PM	#7
jshaf Montani Semper Liberi Drives: 2011 Black 2SS/RS w/ IOM stripes Join Date: Feb 2010 Location: Masontown, WV Posts: 4,841	only time I notice this is when I accidently have it in S mode, and of course not using paddles. __________________ Stainless Works 1 7/8 Long Tude Headers, Stainless Works High Flow Cats, Stainless Works Retro Chambered Catback, Z/28 Air Intake, RDP Tuned, FR41 Chrome Rims, 1100W stereo, 35% Tint

08-31-2015, 10:19 PM	#8
trodecke Drives: 2014 2SS/RS CRT Join Date: Apr 2014 Location: Oklahoma City, OK Posts: 365	I haven't seen that exact issue but I do experience something very much like that. When I'm slowing to a stop, usually as the car is dropping below 10 mph, I feel a definite "bump", like it's making a hard shift from 3rd to 2nd. I don't recall seeing the M2 in the DIC but I do feel the surge. For me though it's every single time. __________________ Lifetime Camaro guy. 1979 Z28, 1987 LT, 2012 2LS, 2014 2SS/RS --CAI Cold Air Intake --Solo HFC

08-26-2015, 07:33 PM	#5
Rock-It Man 376 cubic inches of fun Drives: 2023 Camaro ZL1 A10 Join Date: Jul 2010 Location: MA Posts: 4,033 View My Garage	Are you in S mode when the car decides on its own to go to M?

08-31-2015, 02:15 AM	#6
JSure83 Drives: 2015 Camaro LS1 Join Date: Aug 2015 Location: California Posts: 8	This happens on my 04 Malibu Classic when I'm slowing down to a stop. It's almost like driving a stick and just moving back to 3rd/2nd to help slow down a reduce wear on the brakes. Now granted, I'm selling that car and driving my LS1, but all this to say that my other Chevy car which was an automatic did behave this way. However, it wasn't bumping forward but actually helping slow the car down. Hope that helps.

09-01-2015, 04:42 AM	#9
bork_bork Drives: 2013 ZL1 M6 Convert Triple Black Join Date: Feb 2014 Location: Simpsonville SC Posts: 408	This has happened to me when I have it in sport mode and not manually shifting. Its only happened a couple times though

09-01-2015, 01:12 PM	#10
MrChrisLS3 Drives: 2018 1SS M6 Join Date: Nov 2014 Location: Houston Posts: 2,617	From the description, it sounds like the trans is getting hung up between gears. Automatic transmissions do downshift during deceleration to keep the engine rpms consistent with speed. However, it sounds here like it's taking too long between gears, in other words, like it is riding in neutral too long than slipping into gear, causing the "surging" when coming to a stop.

09-01-2015, 01:27 PM	#11
kevint Drives: 2013 1SS Join Date: Dec 2012 Location: New Jersey Posts: 716	My drop into first at ~6mph is usually pretty obvious.

09-01-2015, 01:34 PM	#12
ClawSS High-tech Redneck Drives: '10 CGM SS, '02 2500HD, '09 300SRT8 Join Date: Nov 2010 Location: Lexington, KY Posts: 757	Are you in "D" when this is happening? Do you have an aftermarket tune installed? __________________ "My friends call me Chris. Are you my friend?" 2010 CGM L99 2SS/RS - GPI SS3 VVT, BTR DoD Delete, Circle D 4c, BTR springs, Katech C5R Timing Chain, MRR-228 315/275, CAI, Elite catch-can, TSP 1 7/8" Headers + offroad pipes, Magnaflow 3", Pfadt springs, BMR LCAs, toelinks, trailing arms, cradle bushings, & sway bars w/ endlinks, Vitesse paddles, heritage grille, and an eBay splitter. Power upgrades by Race Proven Perf.; Tuning by ShorTuning.

09-01-2015, 03:37 PM	#13
kmarshall2121 Drives: 2012 45th Anniversary Edition Join Date: Aug 2012 Location: San Diego, CA Posts: 1,618 View My Garage	I believe its suppose to do this. Mine 'downshifts' on its own when i am de-celerating, or starting to slow down like coming down out of a grade.

09-03-2015, 05:15 PM	#14
Tiberious Old '71 Owner Drives: 11 Camaro Vert;97 Malibu;03 Venture Join Date: Apr 2010 Location: Tacoma, WA Posts: 396	Thanks all. No, I'm in D and I've lightly tapped the shifter to see if there's some way it could just be oversensitive or some physical glitch, no dice. The problem isn't so much that it downshifts, that's to be expected, it's definitely not normal though as it shifts in such a way as the car surges forward just as I'm stopping. Nothing normal about that. Also the fact that it says M1 when I am not manually shifting should make it clear that it's not a normal downshift. No aftermarket tuning, still under extended warranty. I think MrChris has it about right, but without getting the dealer to be able to repeat the problem, I'm not getting any support. My brother in law and nephew both work at GM and are looking into the issue from that end. I can't imagine that I'm the only person with this problem though. Thanks all for the feedback, while I'm disappointed that nobody knows for sure what's going on, I'm glad none of you have the same problem! Tib __________________ Peace was my profession...