16-NA-175: Shake and/or Shudder During Light Throttle Acceleration Between 25 and 80 MPH (40 and 128 KM/H) at a Steady State – 2015-2018 Cadillac Chevrolet GMC

#16-NA-175: Shake and/or Shudder During Light Throttle Acceleration Between 25 and 80 MPH (40 and 128 KM/H) at a Steady State – (Dec 13, 2017)

Subject: Shake and/or Shudder During Light Throttle Acceleration Between 25 and 80 MPH (40 and 128 KM/H) at a Steady State

 


Brand: Model: Model Year: VIN Breakpoint Engine: Transmission:
from to from to
Cadillac GM Passenger Cars and Trucks 2015 2018 November 1, 2015 EOP All 8L90 and 8L45 Automatic (RPOs M5U, M5T, M5N, M5X)
Chevrolet
GMC

 

Involved Region or Country North America, N.A. Export Regions and Korea
Condition Some customers may comment on any of the following conditions:

  • A shake and/or shudder during light throttle acceleration between 25 and 80 mph (40 and 128 km/h) steady state driving when transmission is not actively shifting gears.
  • A shudder feeling that may be described as driving over rumble strips or rough pavement.
  • Shudder feeling is evident in both Drive and M7 MY15-16 & L7 MY17 & MY18 mode.

 

Diagnosis Instructions

To ensure TCC Shudder is diagnosed correctly, please drive the following schedule on a smooth road with transmission sump temperature between 122°F (50°C) – 158°F (70°C).

Important: For some road conditions, it may be required to apply the brake pedal and throttle simultaneously to stay within desired gear, engine firing mode, engine torque range, and engine/vehicle speed ranges.

For Full Size Trucks/SUVs – Press and hold the tow-haul mode button for 5 seconds to disable grade braking to prevent downshifts during test.

Run the following tests for 3 operational modes:

A. Normal Operation (GDS2 for viewing only).

B. GDS2 Commanding TCC in Disabled Operation. (TCC Open).

C. GDS2 Commanding TCC in Enabled Operation. (TCC Locked).

 

Test:

Refer to the table below for conditions pertaining to specific applications. In each vehicle, constant throttle input on a smooth grade is desirable. PicoScope Measured Frequency is the approximate vibration frequency where TCC Shudder can be found, discussed in detail below.

Vehicle Information Shudder Test Conditions PicoScope
Make Application: Engine type Engine RPO Trans RPO Gear Engine Mode (V4, V6, V8) Transmission Input Speed (rpm) Vehicle Speed (mph) Engine Torque (Nm) Measured Frequency (+/- 2 Hz)
Chevrolet/GMC Colorado/Canyon 6 CYL. NA LGZ M5T 8 V6 1100-1500 42-55 150-250 25
Cadillac CTS 6 CYL. NA LGX M5N 8 V6 1100-1500 42-55 100-250 23
Cadillac CTS 4 CYL. Turbo LTG M5N 8 V4 1100-1500 42-55 100-250 23
Cadillac CTS-V 8 CYL. Supercharged LT4 M5U 8 V8 1000-1500 42-62 200-375 28
Cadillac ATS 4 CYL. NA LCV M5T 8 V4 1100-1500 42-55 100-250 23
Cadillac ATS 6 CYL. NA LGX M5N 8 V6 1100-1500 42-55 100-250 23
Cadillac ATS 4 CYL. Turbo LTG M5N 8 V4 1100-1500 42-55 100-250 23
Cadillac ATS-V 6 CYL. Twin Turbo LF4 M5U 8 V6 1100-1500 42-55 150-300 26
Cadillac CT6 6 CYL. Twin Turbo LGW M5X 8 V6 1100-1500 42-55 150-300 26
Cadillac CT6 6 CYL. NA LGX M5N 8 V6 1100-1500 42-55 100-250 23
Cadillac CT6 4 CYL. Turbo LTG M5N 8 V4 1100-1500 42-55 100-250 23
Chevrolet Camaro 6 CYL. NA LGX M5T 8 V6 1100-1500 42-55 100-250 23
Chevrolet Camaro 4 CYL. Turbo LTG M5T 8 V4 1100-1500 42-55 100-250 23
Chevrolet Camaro SS 8 CYL. NA LT1 M5U 8 V4/V8 1000-1,500 40-55 (V4) 100-200 /(V8) 175-375 28
Chevrolet Corvette 8 CYL. NA LT1 M5U 8 V4 (Eco Driving Mode) 1000-1800 40-80 125-250 28
Chevrolet Corvette Z06 8 CYL. Supercharged LT4 M5U 8 V4 (Eco Driving Mode) 1000-1800 40-80 125-250 28
Chevrolet/GMC Silverado/Sierra 8 CYL. NA L83 M5U 8 V8 1050-1500 45-55 200-375 26
Chevrolet/GMC Silverado/Sierra 8 CYL. NA BAS L8B M5X 8 V8 1050-1500 45-55 200-375 26
Chevrolet/GMC/Cadillac Silverado/Sierra/Yukon Denali/Denali XL/Escalade/ESV 8 CYL. NA L86 M5U 8 V8 1050-1500 45-55 200-375 26

*

To confirm TCC Shudder, the vibration concern must be created in normal operation (Mode A) of the test. If the concern is gone with the torque converter clutch disabled (Mode B, TCC Open) and is gone with torque converter clutch enabled (Mode C, TCC Locked), then the vibration root cause is TCC Shudder, and the fluid flush procedure corrective action described below should be performed.

If the concern is not present in Mode A, then the vibration concern is NOT TCC shudder.

If the concern is still present with the torque converter clutch disabled (Mode B) or with the torque converter clutch enabled (Mode C, TCC slip speed at zero), then the vibration root cause is NOT TCC Shudder.

Vibrations not identified as TCC Shudder should be further investigated using the Vehicle Vibration Diagnosis in SI as a starting point.

 

Picoscope Test

The PicoScope (CH-51450) essential tool and NVH software can be used to confirm TCC Shudder, Engine, Tire, or Driveline component related conditions.

To confirm TCC Shudder, record the PicoScope data while driving in 8th gear in the application specific condition above. Minimize extraneous vibration input by testing on a smooth road and correct any other known vehicle vibration issues (tires, brakes, etc.) before conducting test. If TCC Shudder is present, a vibration peak will appear (highlighted by arrow below) within +/-2 Hz of the frequency listed in the table above. TCC Shudder vibration frequency is stationary in 8th gear. If the vibration frequency follows vehicle speed or engine speed, then it is NOT TCC Shudder.

frequency and default view

In the above illustration, frequency and default view have been selected.

 

All Applications EXCEPT 2017-2018 Chevrolet Colorado and GMC Canyon Service Procedure

Important: Requires Mobil 1 Synthetic LV ATF DEXRON HP transmission fluid.

Note: U.S. dealers must order the Mobil 1 Synthetic LV ATF DEXRON HP fluid through your local General Motors oil distributor. When contacting the General Motors oil distributor request Mobil 1 Synthetic LV ATF DEXRON HP. Canadian dealers must order through CCA using the current part number in the Electronic Part Catalog.

  1. Drain, Clean pan/magnet, Replace Filter, Oil Fill, & Remove fluid from the oil cooler lines.

Note: If you find that the fluid is cloudy, milky, or appears to be contaminated with water or engine coolant, DO NOT proceed with below steps. Follow Both SI Procedures for “Cooling System Leak Testing” and “Engine Coolant/Water in Transmission.”

  • C.) Clean the pan/magnet if any metallic particles present and replace transmission filter.

Install the transmission fluid pan and refill with new Mobil 1 Synthetic LV ATF DEXRON HP transmission fluid following the Fluid Fill Procedure in SI to obtain correct fluid level.

The shudder should be improved after the completion of this flush procedure.

Note: Shudder should improve directionally right away, but for full affect, the vehicle may need to be driven up to 200 miles (322 km) and a minimum of two cold to hot drive cycles before determining if the fluid flush corrected the condition or not. Do not re-evaluate vehicle for additional customer shudder concerns until the vehicle has been driven 200 miles (322 km).

 

2017-2018 Chevrolet Colorado and GMC Canyon Service Procedure

  1. Drain, Clean pan/magnet, Replace Filter, Oil Fill, & Remove fluid from the oil cooler lines.

Important: Operate the vehicle on the hoist for 10 minutes. Cycle through all forward gear ranges, Reverse and Neutral.

  1. Drain, Oil Fill, & Circulate New Fluid.

Important: Operate the vehicle on the hoist for 10 minutes. Cycle through all forward gear ranges, Reverse and Neutral.

  1. Drain, Oil level Set, and Drive to Evaluate.

The shudder should be improved after the completion of this triple flush procedure.

Note: Shudder should improve directionally right away, but for full affect, the vehicle may need to be driven up to 200 miles (322 km) and a minimum of two cold to hot drive cycles before determining if the fluid flush corrected the condition or not. Do not re-evaluate vehicle for additional customer shudder concerns until the vehicle has been driven 200 miles (322 km).

 

Warranty Information

For vehicles repaired under the Powertrain coverage, use the following labor operation. Reference the Applicable Warranties section of Investigate Vehicle History (IVH) for coverage information.

Labor Operation Description Labor Time
8480478* Flush and Drain Fluids for Transmission Shake and/or Shutter Repair Use Actual Clock Time
*This is a unique Labor Operation for Bulletin use only.

 

Version 10
Modified June 1, 2016 – Added a breakpoint date.

November 29, 2016 – Added the 2017 Model Year and updated information including graphics under Diagnosis Instructions.

February 27, 2017 – Updated the Model section and added additional information to Test section.

April 18, 2017 – Updated the Shudder Chart information.

August 24, 2017 – Updated information.

September 19, 2017 – Updated the Service Procedure.

October 4, 2017 – Updated VIN breakpoints.

December 1, 2017 – Added the 2018 Model Year and updated Service Procedure sections.

December 14, 2017 – Removed the NOTE statement regarding the use of Dextron VI to flow and flush transmission cooling system.


https://www.nhtsa.gov/recalls?nhtsaId=10114106


https://www.nhtsa.gov/recalls?nhtsaId=10116600


https://www.nhtsa.gov/recalls?nhtsaId=10113985


 

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