Gm 8 Speed Transmission

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The GM 8L45 eight-speed automatic transmission According to TSB (Technical Service Bulletin) 18-NA-355, the latest update addresses “torque converter clutch (TCC) shudder conditions on 8L45. The 8L90E is an 8 speed automatic transmission developed by General Motors and introduced for the 2015 Model year. It is currently phasing out the 6L80/6L90 transmissions (although it hasn’t done its all the way yet. Structurally, the 8L90 is similar to the 8L45, except that it is made to handle more power and torque. It is an incredibly advanced transmission and has the technology to. We would like to show you a description here but the site won’t allow us. TSB Seems To Fix 8-Speed Automatic GM Transmission ProblemsAugust 13, 2019 Multiple GMC Acadia Owners Report ‘Shift To Park’ Issue December 13, 2019 Poll: Should GM Bring Back Pontiac?

Gm 8 Speed Transmission Tuning

A new transmission fluid exchange procedure and a new formula of Mobil 1 Synthetic LV ATF HP transmission fluid have been released to address torque converter clutch (TCC) shudder conditions on 8L45 and 8L90 8-speed automatic transmissions (RPOs M5N, M5T, M5U, M5X) in some 2015-2017 Escalade, Yukon; 2015-2018 Silverado, Sierra; 2015-2019 Corvette; 2016-2018 CT6; 2016-2019 ATS, CTS, Camaro; and 2017-2019 Colorado and Canyon models.

The new fluid exchange procedure requires the use of the DT-45096 TransFlow Cooler Flush Machine and DT-52263 Transmission Fluid Exchange Tool Kit. (Fig. 10) The tool kit began shipping to dealerships at no charge in late January 2019. All GM dealerships should receive the tool kits by the end of March 2019.

Fig. 10

Shudder Test

Gm 8 Speed Transmission

The new service procedure addresses shake and/or shudder conditions during light throttle acceleration between 25 and 80 MPH (40 and 128 KM/H) at a steady speed when the transmission is not shifting gears. To ensure TCC shudder is diagnosed correctly, drive the vehicle on a smooth road with transmission sump temperature between 122°F (50°C) – 158°F (70°C). Constant throttle input on a smooth grade is needed.

A shudder condition may also be a chuggle, surge or vibration condition. Use GDS 2 or the CH-51450 PicoScope to confirm that the concern is TCC shudder and not a tire/wheel vibration or a driveline vibration, for example. A screen print from GDS 2 or the PicoScope showing the TCC shudder event must be attached to the Repair Order hard copy. (Fig. 11)

If TCC shudder is present, a vibration peak will appear within +/- 2 Hz of the frequency listed in Bulletin #18-NA-355. Refer to the bulletin for additional information, including required shudder test conditions for each vehicle being diagnosed as well as the fluid exchange procedures.

Fig. 11

Gm 8 speed transmission mqe

Fluid Exchange

The TCC shudder condition is related to moisture content in the transmission fluid. The current fluid tends to be hydroscopic, or absorbs moisture, which increases the chance of TCC shudder. There are three different fluid exchange procedures to follow, depending on vehicle application, so that an acceptable concentration of the new HP fluid is achieved in the transmission.

The new Mobil 1 Synthetic LV ATF HP transmission fluid is now available to U.S. dealerships through your local GM Oil Distributor. The new Mobil 1 Synthetic LV ATF HP transmission fluid is available in quart bottles (GM Part Number 19417577) and, for a limited time, in 55-gallon drums (GM Part Number 19417904) (Fig. 12) in most locations. Drum production ended in January 2019. The GM part numbers are not on the product. The Mobil 1 Synthetic LV ATF HP fluid and the required tool kit will be available to all Canadian dealerships by the end of March 2019. GM Part Numbers for 0.946 liter bottles will be provided at that time.

Fig. 12

TIP: Mobil 1 Synthetic LV ATF HP transmission fluid is required for all 8-speed transmission repairs regardless of the repair being completed.

Quart bottles, which can be identified by a new blue banner across the front of the bottle (Fig. 13), will be limited to 20 cases/120 quarts per dealer per week during the initial launch of the new product. The new bottles also feature the HP license number J-62120 on the back label. The use of the black label Mobil 1 Synthetic LV ATF HP fluid (GM Part Number 19355656) should be discontinued.


Fig. 13

Gm 8 Speed Transmission Lawsuit

For a video demonstration of the new fluid exchange procedure, check out the December 2018 Emerging Issues Broadcast, course number 10218.12V, available through the Center of Learning. In Canada, refer to the January 2019 TAC Talk seminar.

8 Speed Gmc Transmission Problems

– Thanks to Mark Gordon

Gm 8 Speed Transmission Fix

Updated March 15, 2019