Has anyone heard of this?
When I start my truck either from being cold or warm there is a slight surge of the transmission. It's almost like it's in gear and moves forward very slightly.
I have an automatic transmission. There are no other issues with shifting or surging while driving or stopping.
I just wanted to get some advice before I go to the dealer and they say the standard line "operating as designed". It is still under warranty.

Thanks

 

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I have researched 2009 Silverado vehicles and was unable to find any known surge (transmission related on start-up) issues within my resources.

Please keep us posted on the diagnosis from your dealer.

Louis
GM Customer Service

 

After a trip to the dealer I have no new information.
They can't seem to duplicate the issue.

The strange thing is it happens about 75% of the time on start up.
I'm not sure it's the transmission.
It moves ever so slightly when it occurs and there is a noticeable click.
It's hard to describe, but the truck does move very slightly when it occurs.

 

I have a 99 silverado and mine does the same exact thing. It only does it sometimes and when i start up it just kind of jumps a little but just like you said it moves not much but just a little bit. I am just shy of 200,000 and its the same transmission so i think you be alright. Keep us posted if you actually find something

 

There's actually a TSB for that concern. Click on the "TSB & Recalls" link in the navigation bar above and then look up your vehicle to see if 08-07-30-026 applies. The gist of it is:

"This slight movement is due to the residual transmission fluid in the clutch packs that creates a partial apply on start up. This movement is stopped by the parking pawl and/or transmission fluid exhausting completely from the clutch packs."

"This slight movement has no adverse affects on the transmission and no repair should be attempted. This condition is normal.

 

Leave truck there over night and ask them to start in am

 

I have a 2007 and mine has the same issue. When i run it and come to a red light just after normal warm up it almost feels like i took the truck out of gear and put it back in and it gives me that "bump" one time i almost hit the car in front of me!!! It happens about 75% of the time. I had the trans fluid changed when i hit 50K same thing. Im not really worried about it.

 

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This issue may be caused by a catalyst monitoring diagnostic test. This test is done to monitor catalyst efficiency and can cause a bump or surge when the vehicle comes to a stop (at idle), transmission in gear and the brake applied.

If this is the issue, consult with your service technician at your GM dealer, so they may install the latest ECM calibration.

If you have any additional questions, please feel free to contact me.

Please keep us posted.

Louis
GM Customer Service

 

It sounds just like EinST said. I can't seem to find the TSB based on the code but the condition you wrote sounds right on.

Mine only occurs on start up and not while driving or stopping like bsoxbito has described.

I'm content with EinST answer and will not worry about it. I don't think another trip to the dealer is worth it as this has been going on since the truck was brand new.

Thank you all!!

 

I think that's a wise choice. I get so tired of their free multi-point inspection (read, greasy fingerprints on the glove compartment door for the nonexistent cabin air filter, no less). In fact, call me strange but I'm rather particular about greasy fingerprints anywhere, dings on the doors, and overtightened lug nuts.