Question about 2003 GMC Sierra 1500
There might be million of reasons for the same and to be frank you would agree.Your symptoms point to pressure regulator/ boost valve sticking in valve body. When you shake the valve body from front to rear, you should be able to hear the boost valve rattle. Carefully pry the valves from their seated positions.
They should slide smoothly and return to their seated position without binding. You should be able to buy new valve body gaskets at any tranny shop for a few dollars.A good place to start would be to test the vacuum modulator and be surethe modulator valve in the trans is not stuck, then check the governorfor proper operation and calibration and check it's gear. All can bedone without pulling the pan off.
Another possibility might be the center seal being left out of thedirect drum for a greater fluid appy area in third, you need to block areverse passage when doing this or reverse will come on with third.This plug may have come loose if it actually worked at one time.
Also, check for CODES. This is very important as i am sure you would get certain codes like
740 753 758 in this case .
The most likely cause of this condition may be a loss of voltage to the transmission solenoid power supply circuit.
Thiscondition may also be the result of an incorrect installation of anaftermarket electronic device such as a remote starter or alarm system.
Hope i helped you.
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Posted on Jul 02, 2009
Forward sprag assembly came apart in transmission. This is very common with these 4L60E transmissions.
Posted on Jun 28, 2009
I can't see what the other replies to you were but I can tell you this, if you can get your truck to AAMCO transmission shop, they will evaluate it for free and will not doing anything to it without your consent. If you don't have that type of transmission specialst around, take it to one that is reputable. But, from YOUR replies, it sounds as if your tranny is bad and needs a rebuild. I know it is not a ricket scientist answer but unless you have the special tools to overhaul it, take it in to get repaired.
Regardless of what the "experts" here say, you are the one that will be without your truck and the one paying for it, not us.
Take it in and get it rebuilt.
Posted on Jun 29, 2009
This sounds like a timing issue. When you go up a grade, or have a loss of
power, it sounds like your timing isnt retarding enough. I cant remember
though whether you have vacuum advance on those vehicles anymore or not.. If
you have it, check for a vacuum leak. If you dont have it, the check your
Check your knock sensor, also. Had a similar problem, and that was the solution
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Posted on Jun 28, 2009
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Posted on Jan 02, 2017
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