According to the technical service bulletin TSB PIP4304A, the 2008 GMC Yukon Denali & 2008 GMC Yukon Denali XL equipped with either the 6L80 transmission or 6L90 transmission may experience one or more the following symptoms; slipping in 1st, 2nd, 3rd or 4th gears. Owners can also experience a rather pronounced 2 – 3 second delay from the time they shift out of park or reverse and into drive. The following trouble codes/DTC’s will also accompany this issue; P0878, P2714 & P2723.
What Transmission Do I Have?
In this technical service bulletin, you will find General Motors’ recommended repairs for this problem. For example, should the transmission fluid be dark or burnt, with the presence of clutch debris on the dipstick or in the transmission pan, then the 1 – 2 – 3 – 4 clutch plates will have to be replaced. The entire transmission will also have to be inspected to ensure that no damage was caused by the clutch debris. In addition, the transmission cooler will have to be flushed out.
If none of those issues apply, yet the problem remains, then the control solenoid valve and transmission control module and assembly, along with the 1 – 2 – 3 – 4 clutch plates will also have to be replaced.
This is obviously a very complicated job, and the labor hours are going to run pretty high. At this point, it might make the most sense to simply rebuild the transmission while it is out of the truck. But if you want to keep your Denali on the road for as long as possible, you’re going to want to upgrade to a remanufactured 6L80 transmission or remanufactured 6L90 transmission from a company like Street Smart Transmission.
What Transmission Do I Have?
They completely reengineer each transmission to address the numerous factory design flaws (like this one). Then they dyno test each one before it leaves the factory, to ensure that it performs properly right out of the box. And you also get a 3-year/unlimited mile nationwide warranty to protect you and your wallet down the road. If you would like to learn more, simply click here.
