2.4L - intermittent hard shifting and t/c light - no MIL - HELP!
07-22-2009, 04:53 PM
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2.4L - intermittent hard shifting and t/c light - no MIL - HELP!
Hi all,
I haven't been on this forum in forever because I decided not to modify my car at all (the original reason I joined...) My Cobalt doesn't even have aftermarket floormats... but now I'm really hoping that someone here can save my butt!
'06 Chevy Cobalt SS (2.4L, no super) starting doing this about a week ago: once in a while, while performing a shift – maybe 2-3x a week and I do a lot of driving – the traction control light will come on and it seems the transmission controller goes into a subroutine where it does not limit the pressure to the clutch plates. I get very hard shifts like this until I turn the car off and then on again. There is no MIL, so I don’t know if a code is being stored. I'm told that such a code would be wiped from memory on restart (which may or may not be why the problem clears up?)
Otherwise, the transmission operates completely normally, shifting at the appropriate points regardless of whether it’s in the “hard shift routine.” I'm not sure if this is only happening on something like a hard upshift or it's random - I'll try to test more and get more detailed information on what triggers it. Sounds like my tranny is killing itself when it shifts though, it's very firm!
Does this strike anyone as a mechanical problem that’s triggering a subroutine in the computer, or as an electrical/electronic problem? Some kind of sensor? I’d appreciate any insight!
Oh, and I did read this thread: https://www.cobaltss.net/forums/drivetrain-79/auto-hard-shifting-help-174088/
Perhaps it leads me to believe it's an electrical problem... I don't know.
A very friendly and trustworthy mechanic is going to get the car on Friday morning and try to test drive and duplicate the problem while he has a code reader plugged in to see if he gets anything.
Update: Borrowed my friend's DashHawk and am leaving it plugged in to try to catch any codes in real time. There are none stored in memory. I can monitor things like O2 sensor voltages and MAF, let me know if I should expect or not expect anything with those values...?
Thanks again!
I haven't been on this forum in forever because I decided not to modify my car at all (the original reason I joined...) My Cobalt doesn't even have aftermarket floormats... but now I'm really hoping that someone here can save my butt!
'06 Chevy Cobalt SS (2.4L, no super) starting doing this about a week ago: once in a while, while performing a shift – maybe 2-3x a week and I do a lot of driving – the traction control light will come on and it seems the transmission controller goes into a subroutine where it does not limit the pressure to the clutch plates. I get very hard shifts like this until I turn the car off and then on again. There is no MIL, so I don’t know if a code is being stored. I'm told that such a code would be wiped from memory on restart (which may or may not be why the problem clears up?)
Otherwise, the transmission operates completely normally, shifting at the appropriate points regardless of whether it’s in the “hard shift routine.” I'm not sure if this is only happening on something like a hard upshift or it's random - I'll try to test more and get more detailed information on what triggers it. Sounds like my tranny is killing itself when it shifts though, it's very firm!
Does this strike anyone as a mechanical problem that’s triggering a subroutine in the computer, or as an electrical/electronic problem? Some kind of sensor? I’d appreciate any insight!
Oh, and I did read this thread: https://www.cobaltss.net/forums/drivetrain-79/auto-hard-shifting-help-174088/
Perhaps it leads me to believe it's an electrical problem... I don't know.
A very friendly and trustworthy mechanic is going to get the car on Friday morning and try to test drive and duplicate the problem while he has a code reader plugged in to see if he gets anything.
Update: Borrowed my friend's DashHawk and am leaving it plugged in to try to catch any codes in real time. There are none stored in memory. I can monitor things like O2 sensor voltages and MAF, let me know if I should expect or not expect anything with those values...?
Thanks again!
Last edited by Soopahmahn; 07-23-2009 at 08:33 AM. Reason: Automerged Doublepost
07-31-2009, 06:01 PM
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I have been having the same problem for about a month and a half now. Exact same symptoms and it seems to happen if I press on the gas more right before it shifts into it's next gear, normally from 1-2. Hopefully someone can find a definite fix for this however I have seen in another thread that someone took theres to a dealership and had the fuses swapped that control the transmission and that fixed it. I haven't tried that yet but it would be nice to hear if others have found a fix.
08-05-2009, 02:04 PM
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I am also having the same issue - it does it when ever the tires spin - the traction control light will come on and then i get the hard shifting. It also seems to do it when i step hard on the gas and then let off...
08-05-2009, 02:18 PM
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Well, no one is going to like to hear this one, cause the fix is expensive (if you are out of warranty). This was how it was listed on my invoice when I had this fixed in June.
You will set codes CO110/CO116. There will be no SES light, the only symptom is the Traction Control light or ABS light on. This is related to the EBCM (Electronic Brake Control Module) & BPMV (Brake Power Modulation Valve?). Basically, your ABS control module and brake fluid distribution block have failed. Since traction control is linked to the ABS system, that is why you get the traction control light and the hard shifts (transmission in protection mode). I had the exact same symptoms and that was the fix. When it was all said and done, you are looking in about $500 for the modules alone! The EBCM is the second most expensive module in the car next to the PCM itself! My labor was $336 from my dealership too! So, count on $1000 if you go to the dealership.
Sorry for the bad news!
You will set codes CO110/CO116. There will be no SES light, the only symptom is the Traction Control light or ABS light on. This is related to the EBCM (Electronic Brake Control Module) & BPMV (Brake Power Modulation Valve?). Basically, your ABS control module and brake fluid distribution block have failed. Since traction control is linked to the ABS system, that is why you get the traction control light and the hard shifts (transmission in protection mode). I had the exact same symptoms and that was the fix. When it was all said and done, you are looking in about $500 for the modules alone! The EBCM is the second most expensive module in the car next to the PCM itself! My labor was $336 from my dealership too! So, count on $1000 if you go to the dealership.
Sorry for the bad news!
08-05-2009, 08:18 PM
#5
Senior Member
Well, no one is going to like to hear this one, cause the fix is expensive (if you are out of warranty). This was how it was listed on my invoice when I had this fixed in June.
You will set codes CO110/CO116. There will be no SES light, the only symptom is the Traction Control light or ABS light on. This is related to the EBCM (Electronic Brake Control Module) & BPMV (Brake Power Modulation Valve?). Basically, your ABS control module and brake fluid distribution block have failed. Since traction control is linked to the ABS system, that is why you get the traction control light and the hard shifts (transmission in protection mode). I had the exact same symptoms and that was the fix. When it was all said and done, you are looking in about $500 for the modules alone! The EBCM is the second most expensive module in the car next to the PCM itself! My labor was $336 from my dealership too! So, count on $1000 if you go to the dealership.
Sorry for the bad news!
You will set codes CO110/CO116. There will be no SES light, the only symptom is the Traction Control light or ABS light on. This is related to the EBCM (Electronic Brake Control Module) & BPMV (Brake Power Modulation Valve?). Basically, your ABS control module and brake fluid distribution block have failed. Since traction control is linked to the ABS system, that is why you get the traction control light and the hard shifts (transmission in protection mode). I had the exact same symptoms and that was the fix. When it was all said and done, you are looking in about $500 for the modules alone! The EBCM is the second most expensive module in the car next to the PCM itself! My labor was $336 from my dealership too! So, count on $1000 if you go to the dealership.
Sorry for the bad news!
After all that are you sure the dealer you went to is Reputable.
Otherwise I would of liked a second opinion.
08-06-2009, 09:00 AM
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Yes, the dealership is reputable and trustworthy. I was referred to them by a fellow ClubGP member who used to work there. I have been going there for a few years. Their service is excellent, the people are friendly, and this dealership has been there for many, many years. They have helped me out even though my car was not bought there (I bought it in Michigan when I lived up North).
And the best proof of all.....the problem was fixed!
And the best proof of all.....the problem was fixed!
01-29-2010, 01:45 PM
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::Bumpin' like it's 2001::
It's been a while since my OP but I took a while to isolate the issue. When the T/C light would throw, there was no code stored in history - but P0106 was activated with the light.
http://www.obd-codes.com/p0106
I didn't feel anything, but I was also racking up some misfires in a couple of cylinders. I learned not to feather the throttle and avoided accelerating too hard, and it didn't recur often so I left it alone for a while to see if it would sort itself out.
In the meanwhile, the stainless flex downpipe from the exhaust manifold rotted out and - guess what? - that's an integral part of the catalytic converter. That cost me $600 in P+L to fix. Thank you, nameless GM engineer.
Within a few days after fixing, my check engine light came on a few times. It would typically occur at high speed (65-70 mph) while cruise controlling down the freeway. Code was P1174 (air:fuel mixture imbalance between cylinders). It would clear after 3 ignition cycles and wouldn't come back for a while, but it did persist 3-4x before I made it into my Chevy dealer.
<Backstory: this dealer replaced all of my fuel injectors 10 months and 15,000 miles prior. The SES light had come on and, guess what... it was P1174. $650 later...>
The fix: updated ECM calibration data from GM - a reflash for the computer. Cost $95. As the car wears, performance parameters and the interaction of all the systems changes. The manufacturer attempts to compensate for this in their system model, but often they miss the mark. My car was mechanically perfect, but was throwing the check engine light and driving very stupidly because the model was probably running some cylinders lean (who knows what else). You get a new fuel map, etc.
End result: my car actually feels a heck of a lot newer than it did. Fuel economy is up 10-15%, shifts are much smoother, the throttle is much more responsive, and I honestly believe I may have gained up to 10 peak horsepower and definitely have more torque across the powerband. This car is fun to drive again. It was on a downhill slide for a year or two and I barely noticed/chalked it up to age. No more T/C lights or SES lights.
I would recommend checking into this if your Cobalt is aging, getting poor fuel economy (and it's not a typical suspect like air filter), or throwing the T/C light/exhibiting P1174. Ask your dealer if your car is a candidate for an ECM update. If I find a link to the appropriate bulletin, I will share.
It's been a while since my OP but I took a while to isolate the issue. When the T/C light would throw, there was no code stored in history - but P0106 was activated with the light.
http://www.obd-codes.com/p0106
I didn't feel anything, but I was also racking up some misfires in a couple of cylinders. I learned not to feather the throttle and avoided accelerating too hard, and it didn't recur often so I left it alone for a while to see if it would sort itself out.
In the meanwhile, the stainless flex downpipe from the exhaust manifold rotted out and - guess what? - that's an integral part of the catalytic converter. That cost me $600 in P+L to fix. Thank you, nameless GM engineer.
Within a few days after fixing, my check engine light came on a few times. It would typically occur at high speed (65-70 mph) while cruise controlling down the freeway. Code was P1174 (air:fuel mixture imbalance between cylinders). It would clear after 3 ignition cycles and wouldn't come back for a while, but it did persist 3-4x before I made it into my Chevy dealer.
<Backstory: this dealer replaced all of my fuel injectors 10 months and 15,000 miles prior. The SES light had come on and, guess what... it was P1174. $650 later...>
The fix: updated ECM calibration data from GM - a reflash for the computer. Cost $95. As the car wears, performance parameters and the interaction of all the systems changes. The manufacturer attempts to compensate for this in their system model, but often they miss the mark. My car was mechanically perfect, but was throwing the check engine light and driving very stupidly because the model was probably running some cylinders lean (who knows what else). You get a new fuel map, etc.
End result: my car actually feels a heck of a lot newer than it did. Fuel economy is up 10-15%, shifts are much smoother, the throttle is much more responsive, and I honestly believe I may have gained up to 10 peak horsepower and definitely have more torque across the powerband. This car is fun to drive again. It was on a downhill slide for a year or two and I barely noticed/chalked it up to age. No more T/C lights or SES lights.
I would recommend checking into this if your Cobalt is aging, getting poor fuel economy (and it's not a typical suspect like air filter), or throwing the T/C light/exhibiting P1174. Ask your dealer if your car is a candidate for an ECM update. If I find a link to the appropriate bulletin, I will share.
01-29-2010, 03:13 PM
#9
Senior Member
Here you go:
Document ID# 1870295
2006 Chevrolet Cobalt
--------------------------------------------------------------------------------
Subject: SES Light With No Engine Performance Concerns And A P1174 DTC - Reprogram ECM - keywords calibration CEL ECM light MIL PCM repeat SES #PIP3968 - (11/02/2006)
Models: 2006 Chevrolet Cobalt
2006 Chevrolet HHR
2006 Chevrolet Malibu
2006 Pontiac G6
2006 Pontiac Pursuit (Canada Only)
2006 Pontiac Solstice
2006 Saturn Ion
Manufactured Before 10/01/2005
with a 2.4L Engine (VIN B or P - RPO LE5)
--------------------------------------------------------------------------------
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
On rare occasions, a SES light may be experienced with no engine performance concerns and a P1174 DTC. This PI does not apply if there are any engine performance concerns or other engine performance DTCs, such as a P0300.
Recommendation/Instructions:
If the SI diagnostics do not isolate a cause for this concern, reprogram the ECM with the latest engine calibration. At this time, the latest engine calibration are titled "new calibration with diagnostic enhancements for DTCs P1682 and P1516 and fix for stall immediately after remote start", This calibration, or any that follow, is designed to address this concern.
Found this little tidbit as well
I think it refers to the maf sensor causing the shift problems.
#04-07-30-013B Info - Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon (SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air Filter - (Feb 1, 2007)
Document ID# 1870295
2006 Chevrolet Cobalt
--------------------------------------------------------------------------------
Subject: SES Light With No Engine Performance Concerns And A P1174 DTC - Reprogram ECM - keywords calibration CEL ECM light MIL PCM repeat SES #PIP3968 - (11/02/2006)
Models: 2006 Chevrolet Cobalt
2006 Chevrolet HHR
2006 Chevrolet Malibu
2006 Pontiac G6
2006 Pontiac Pursuit (Canada Only)
2006 Pontiac Solstice
2006 Saturn Ion
Manufactured Before 10/01/2005
with a 2.4L Engine (VIN B or P - RPO LE5)
--------------------------------------------------------------------------------
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
On rare occasions, a SES light may be experienced with no engine performance concerns and a P1174 DTC. This PI does not apply if there are any engine performance concerns or other engine performance DTCs, such as a P0300.
Recommendation/Instructions:
If the SI diagnostics do not isolate a cause for this concern, reprogram the ECM with the latest engine calibration. At this time, the latest engine calibration are titled "new calibration with diagnostic enhancements for DTCs P1682 and P1516 and fix for stall immediately after remote start", This calibration, or any that follow, is designed to address this concern.
Found this little tidbit as well
I think it refers to the maf sensor causing the shift problems.
#04-07-30-013B Info - Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon (SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air Filter - (Feb 1, 2007)
Last edited by Coblasts; 01-29-2010 at 03:13 PM. Reason: Automerged Doublepost
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