GM Service Manual Online
For 1990-2009 cars only

If the garage door opener system is inoperative, verify the following conditions before performing the garage door opener functional test:

    â€¢ Verify that the codes in the receiver and the transmitter are the same.
    â€¢ Verify that the receiver unit has electrical power through the 110V transformer.
    â€¢ Verify that the operating device has power.
    â€¢ Inspect the receiver hook up wiring for damage. Breaks in the wire are usually found under the staples, ect., or at the connections.
    â€¢ Verify that the installation of the antenna in the receiver is proper.