Vibration, Shudder or Roughness While Driving at Low Steady Speeds in V4 Mode – 2011 Cadillac Chevrolet & GMC

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Bulletin No.: PI1413
Date: Feb-2015
Subject: Diagnostic Tip for Vibration, Shudder or Roughness While Driving at Low Steady Speeds in V4 Mode
Models: 2011 Cadillac Escalade Models
2011 Chevrolet Avalanche, Camaro, Silverado, Suburban, Tahoe
2011 GMC Sierra, Yukon Models
Equipped with Active Fuel Management V8 Engines (RPOs LC9, LMG, LZ1, L77, L94, L99) and 6L80
Automatic Transmission (RPO MYC)
Attention: This PI also applies to any of the above models that may be Export vehicles.
Condition/Concern
Some customers may comment on a vibration, shudder or roughness while driving at low speeds with a steady throttle on a level road.
Customers may also comment that the condition is more noticeable when driving up an incline.
This concern will be most noticeable when the vehicle is operating in V4 mode, Active Fuel Management (AFM).
Recommendation/Instructions
The root cause of this concern may be a broken torque converter clutch regulator valve spring (353) in the lower valve body, causing the torque converter
clutch (TCC) slip speed to drop to zero.
Monitor the TCC slip speed during the concern while driving with a steady throttle input. If the TCC slip speed is a constant zero RPM during the concern,
inspect the lower valve body for a broken torque converter clutch regulator valve spring (353).
Note: During the road test, the TCC slip may momentarily drop to zero and then climb to 30-50 RPM of slip. This is the normal operation of the TCC.
If the torque converter clutch regulator valve spring (353) is broken, replace the lower valve body.

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