Tahoe 2WD V8-4.8L (2008)
Control Module: Customer Interest
A/T - Intermittent Boom, Rumbling Noise
TECHNICAL
Bulletin No.: 11-07-30-002
Date: March 21, 2011
Subject: Intermittent Boom, Rumbling Noise and/or Disturbance Heard in Passenger Compartment While Driving at Highway Speeds (Reprogram TCM
)
Models:
2008 Chevrolet Tahoe
2008 GMC Yukon
Equipped with 4.8L Engine (RPO LY2) and 4L60E Automatic Transmission (RPO M30)
Condition
Some customers may comment on an intermittent boom, rumbling noise and/or disturbance heard in the passenger compartment while driving the vehicle
at highway speeds. This condition occurs while driving at steady speeds, approximately 88 km/h (55 mph), between 1200-1400 engine RPM in 4th gear
(NOT during acceleration).
Cause
The noise/disturbance occurs when the torque converter clutch (TCC) momentarily goes to a full lock-up state, resulting in zero slip of the torque
converter. When the TCC returns to normal electronically controlled capacity clutch (ECCC) mode with 30 RPM of slip, the noise will go away. The
disturbance generated by the zero slip condition is amplified and transferred into the passenger compartment by the suspension.
Correction
Important
This calibration may affect fuel economy and should not be used in a vehicle without this concern. Read the descriptions to determine the
correct calibration for this vehicle. This is a revised version of the earlier calibration that was released to address this condition.
1. Verify this condition by driving the vehicle to duplicate the concern and using the Tech 2(R) to turn off the TCC.
2. If the noise stops when the TCC is turned off, the calibration detailed below should help to eliminate the noise or vibration.
Important
Verify that the 12-volt battery has a battery charge of 12 to 16 volts. The battery must be able to maintain a charge during programming.
Only use an approved Midtronics 165-PCS charger or equivalent to maintain proper battery voltage during programming.
Note
The J2534 MDI will reprogram the modules in less time than the Tech 2(R) scan tool.
3. Technicians are to reprogram the transmission control module (TCM) using SPS with the latest software available on TIS2WEB. Refer to the
Service Programming System (SPS) procedures in SI. Make sure your Tech 2(R) is updated with the latest software version.
Warranty Information
For vehicles repaired under warranty, use the table.
Disclaimer
