According to the technical service bulletin TSB PIP4304A, the 2008 GMC Sierra 1500 equipped with the 6L80 transmission or 6L90 transmission is likely to experience one or more of the following symptoms; slipping in 1st, 2nd, 3rd or 4th gears. It’s also possible that the truck will experience a 2 – 3 second delay when shifting out of Park or reverse and into drive (known as the garage shift). The following diagnostic trouble codes/DTC’s will also be present; P0878, P2714 & P2723.
What Transmission Do I Have?
This technical service bulletin for the GMC Sierra also outlines common repairs for this problem. For example, if the transmission fluid appears to be dark/burnt, and there is clutch debris on the dipstick or in the bottom of the transmission pan, then the 1 – 2 – 3 – 4 clutch plates will need to be replaced. The rest of the transmission will also need to be carefully inspected to see if there is any damage caused by that clutch debris. The transmission cooler will also need to be flushed.
If none of that applies and the problem still persists, then the control solenoid valve and transmission control module assembly, along with the aforementioned clutches will all need to be replaced.
Because this is a fairly complicated job, the labor hours are going to be expensive. This is why most mechanics will recommend just having the entire transmission rebuilt while it is out of the truck. But if you want to keep your Sierra 1500 on the road for as long as possible, then you’ll want to consider upgrading to a completely remanufactured 6L80 transmission or 6L90 transmission from a company like Street Smart Transmission.
What Transmission Do I Have?
These reman transmissions are completely reengineered to address these factory design flaws, that way they outlast the original transmission. They are also fully tested to ensure that they will function properly right out of the box. And you get a 3-year/unlimited mile nationwide warranty to protect your wallet and your investment. If you would like to learn more, simply click here.
