Envoy 2WD L6-4.2L (2008)
Control Module: Customer Interest
A/T Controls - Highway Speed Booming/Rumbling Noises
TECHNICAL
Bulletin No.: 09-07-30-003B
Date: July 31, 2009
Subject: Intermittent Boom, Rumbling Noise and/or Disturbance Heard in Passenger Compartment While Driving at Highway Speeds (Reprogram TCM
)
Models:
2008-2009 Chevrolet TrailBlazer
2008-2009 GMC Envoy Equipped with Rear Coil Springs
Equipped with 4.2L Engine (RPO LL8) and 4L60 Automatic Transmission (RPO M30)
Supercede:
This bulletin is being revised to add additional Models and advise that the calibration available to address this condition has been revised from the earlier
version. Please discard Corporate Bulletin Number 09-07-30-003A (Section 07 - Transmission/Transaxle).
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 between 1400-1600 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 rear coil springs.
Correction
Important
This calibration may result in decreased fuel economy up to approximately one MPG. This software 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
There are two calibration part numbers that are "selectable" for this controller. Select the calibration labeled "Select this Calibration
only to address TCC boom at 1400-1600 RPM." 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. 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 above.
