Intermittent Erratic Speedometer - Chevy Cobalt Forum / Cobalt Reviews / Cobalt SS / Cobalt Parts
Problems and Service Talk about any mechanical problems you are having

 
LinkBack Thread Tools Display Modes
post #1 of 8 (permalink) Old 06-13-2018, 10:42 AM Thread Starter
Newcomer
 
Join Date: Jun 2018
Location: Houston Area
Posts: 5
Intermittent Erratic Speedometer

The speedometer has started jumping around while car is in park or while maintaining speed. It'll affect cruise control (obviously) and will sometimes even cancel it. It will also sometimes cut power after it starts jumping around. All other gauges are fine. A/T shifts fine. Again, not experiencing symptoms during acceleration.

FYI I have been putting off a P0135 CEL (upstream O2 sensor I believe) since car registration will be current for several months. As of this post, though, I couldn't tell you if a second CEL code has popped up.

2005 Cobalt 2.2L A/T Base, non-ABS
-Injen Short Ram Intake
-B&M A/T Shift Kit
-Dash Cluster from Cobalt 2.4L

I included some links to threads addressing somewhat similar symptoms. Some with solutions, some without. Thanks in advance for your help!

https://www.yourcobalt.com/forums/pro...-shifting.html

https://www.yourcobalt.com/forums/che...ps-around.html

https://www.yourcobalt.com/forums/tra...ed-sensor.html

https://www.yourcobalt.com/forums/pro...en-sensor.html
mcs92 is offline  
Sponsored Links
Advertisement
 
post #2 of 8 (permalink) Old 06-13-2018, 06:31 PM
Super Moderator
YourCobalt.com Premium Member


 
Coby7's Avatar
 
Join Date: Oct 2011
Location: Magnetic Hill, New-Brunswick
Posts: 11,820
Garage
P0135 would not cause your speedometer to bounce.

Bad ground or VSS Vehicle Speed Sensor on transmission output shaft passenger side.

Every minute spent angry is a happy minute lost for ever and ever!!!
Drives 2016 Cocoa Buick Encore 1.4L Turbo auto KL4CJDSB2GB652675
Drives 2016 Sunset Orange Trax LT1 1.4L Turbo auto 3GNCJPSB8GL142716

Never drive faster than your guardian angel can fly
Coby7 is offline  
post #3 of 8 (permalink) Old 06-14-2018, 05:12 AM Thread Starter
Newcomer
 
Join Date: Jun 2018
Location: Houston Area
Posts: 5
It wouldn't be any of the BCM plug issues mentioned in the other threads?

Not complaining. I'd much rather just futz with a sensor than a whole computer module...
mcs92 is offline  
 
post #4 of 8 (permalink) Old 06-14-2018, 05:57 AM
Super Moderator
YourCobalt.com Premium Member


 
Coby7's Avatar
 
Join Date: Oct 2011
Location: Magnetic Hill, New-Brunswick
Posts: 11,820
Garage
Well it could but if you had GMLan breakdown at the BCM you'd have other symptoms. I think your issue is somewhere between the "VSS" and the PCM. Most likely corrosion at either end.

Every minute spent angry is a happy minute lost for ever and ever!!!
Drives 2016 Cocoa Buick Encore 1.4L Turbo auto KL4CJDSB2GB652675
Drives 2016 Sunset Orange Trax LT1 1.4L Turbo auto 3GNCJPSB8GL142716

Never drive faster than your guardian angel can fly
Coby7 is offline  
post #5 of 8 (permalink) Old 06-14-2018, 07:20 AM Thread Starter
Newcomer
 
Join Date: Jun 2018
Location: Houston Area
Posts: 5
Will a bad VSS signal throw a code?
mcs92 is offline  
post #6 of 8 (permalink) Old 06-14-2018, 11:48 AM
Super Moderator
YourCobalt.com Premium Member


 
Coby7's Avatar
 
Join Date: Oct 2011
Location: Magnetic Hill, New-Brunswick
Posts: 11,820
Garage
If it totally fails yes but an intermittent one could take a while since it needs to be nad for something like 10 seconds.

Every minute spent angry is a happy minute lost for ever and ever!!!
Drives 2016 Cocoa Buick Encore 1.4L Turbo auto KL4CJDSB2GB652675
Drives 2016 Sunset Orange Trax LT1 1.4L Turbo auto 3GNCJPSB8GL142716

Never drive faster than your guardian angel can fly
Coby7 is offline  
post #7 of 8 (permalink) Old 06-16-2018, 04:41 PM
Newcomer
 
Join Date: Apr 2018
Posts: 1
I just finished fixing my multi symptom mess on my 2010 Cobalt. If you are experiencing multi symptoms you must check through all the wiring harness under the hood. The plastic conduit on much of the wire harness was cracking and hardened. I finally found a clump of wires butted up against an edge of a part attached to the engine. The plastic conduit looked fine from first view, but when I was checking some wires for continuity I got some changes as I wiggled some wires and finally found those wires shorting onto the engine part. The short caused an engine manifold pressure code, an exhaust solenoid code , and a shift solenoid B code that was causing horrible transmission shifting problems. These were low and high circuit codes because those wires were shorting directly to ground and probably to each other. I coated the wires with silicon rubber and put new conduit on, and plastic tied them off of the engine. All problems solved.
tlaboc77 is offline  
post #8 of 8 (permalink) Old 06-19-2018, 05:51 AM Thread Starter
Newcomer
 
Join Date: Jun 2018
Location: Houston Area
Posts: 5
I actually found a similar solution to my problem. After finding the videos below on YouTube, I discovered the harness near the receptacle for the oil filter had about 8" missing conduit that had disintegrated. Lo and behold, the VSS wires (purple and yellow braided together on my '05 2.2 auto) had worn insulation from a sharp edge on the oil filter receptacle and I believe were shorting to ground and causing my wonky speedo signal (and eventual shifting an driveability issues).


mcs92 is offline  
Sponsored Links
Advertisement
 
Closed Thread

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome