GM Service Manual Online
For 1990-2009 cars only

Battery voltage is supplied to the system from the 47 fuse in the underhood fuse block. The system is grounded at the G300 chassis harness ground. The key fobs and exit/learn switch are inputs to the receiver module. The receiver module commands the master motor through the Wake Up, Open, and Close signal circuits and controls the cargo lamp through a low side drive control circuit. The power tonneau is operated by 2 motors that drive left and right side drive cables. The master motor commands the slave motor through an X Bus communication circuit and the slave motor communicates its status back to the master motor. During power tonneau operation if either motor fails or encounters excessive resistance both motors will be stopped.