The 6T70/75 transmission uses a pressure control system to apply and release clutchesduring shifts. The transmission control module (TCM) controls pressure commands tothe pressure control solenoids.
As normal wear of the transmission clutches occur, the TCM performs a clutch functionverification. The TCM momentarily commands a clutch on at a low pressure. The clutchfunction verification is conducted on smooth roads when the transmission is not shiftingand engine torque is consistent and positive.
When a clutch function verification is occurring, a slight bump or drag may be detectedmomentarily. The clutch function verification will occur a few times over severalminutes and will not repeat again for a thousand or more miles. This is a normalcondition and no repair attempts should be performed.
The clutch function verification will be performed sooner for a particular clutchif the TCM detects it is producing frequent poor shift control.
Compass
The vehicle may have a compass
display on the Driver Information
Center (DIC). The compass receives
its heading and other information
from the Global Positioning
System (GPS) antenna,
StabiliTrak, and vehicle speed
information.
The compass system is designed to
operate for a certain numbe ...