Gm needs to do a recall to fix this problem for all affected vehicles as people, especially those that are on fixed incomes, are not able to pay out of pocket for a test just to validate the toque converter clutch shudder does exist. According to TSB (Technical Service Bulletin) 18-NA-355, the latest update addresses torque converter clutch (TCC) shudder conditions on 8L45 and 8L90. This is a very serious vehicle safety issue that can cause accidents if the driver is not accustomed to being tossed about in their seat while driving the Canyon. , hundreds of dollars) to confirm there is a problem and then determine if warranty will cover the repair(s). Needless to say, gm (corporate and dealership) want us to pay out of pocket for a very expensive diagnostics test (e. We found a copy of the torque converter clutch sb and it applies to all GMC Canyons from 2017-2019. Furthermore, we just learned of a gm service bulletin, 18-na-355 dated August, 2019, that has been circulating. Our Canyon is still under warranty as we have the extended powertrain warranty. As we clear the intersection, the shaking occurs and as the Canyon reduces speed momentarily, we have almost been rear ended. Bulletin No. This time dealers are told to diagnose the. Chevy and GMC dealers were told in previous technical service bulletins to install updated engine control module calibration and perform an oil consumption test. Our biggest concern is that it happens on major roads whenever we accelerate after a traffic light transitions from red to green. General Motors' Technical Service Bulletin (TSB 15285C) could be the answer you've been looking for regarding excessive oil consumption. It is almost as if the Canyon is being rear ended by another vehicle as we're driving down the street. It is very disturbing driving down the street and the Canyon begins to shake so hard that everyone is jarred in their seats even with seat belts on. If the shudder occurs above 64 km/h (40 mp/h) or with the TCC commanded on TSB 17-NA-317 should be reviewed.For several months, we are now continuously experiencing a shaking and shuddering of the Canyon every time the truck shifts from 1st to 2nd gear. But when I saw the latest bulletin posted on this forum that GM was now ready to go ahead and do the fluid flush and change w/o the scope test etc. TSB-NA-355 was reference on the paperwork. A minimum of 200 miles (322 km) needs to be driven after the drain and fill to confirm the repair. Shudder TSB 18-NA-355 has been updated 7/19.

Also, drain and refill the transmission using DEXRON VI as per SI.

If confirmed to be a TCC shudder while monitoring TCC slip speed during the concern, or the concern goes away when TCC is commanded on with the scan tool and the concern is present at 64 km/h (40 mp/h) or below during the gear shift, reprogram the Transmission Control Module (TCM) with the latest calibrations including following the procedure in SI that requires to perform Service Fast Learn (SFL) after programming TCM. I heard some dealers are already getting the new Mobil 1 ATF formula as we speak. Service Bulletin Bulletin No.: 18-NA-355 Date. It should make it to the dealers soon, if it hasn't already, in addition to the new Mobil 1 ATF formula. Tranny instant shudder fix to your GM 8 speed transmission 8L90 8L45 Service Bulletin. This condition may be caused by possible torque converter clutch (TCC) shudder on reapply after a shift. GM-4-LIFE Discussion starter Dec 13, 2018. Summary: Some customers may comment on a slight shudder felt during gear shift at slow speeds below 64 km/h (40 mp/h) with light throttle application. Chevrolet TSB 18-NA-091 Make: Chevrolet Number: 18-NA-091 Title: Slight Shudder Felt During Gear Shift at Slow Speeds Below 64 km/h (40 mp/h) with Light Throttle Application Date: Models:

Gm service bulletin 18 na 355