1999-2001 Cadillac Catera. 1999-2006 Cadillac DeVille, Escalade Models, ... 2005-2006 Cadillac. STS. Service Information. 2002-2006 Chevrolet Avalanche, Cavalier, ... If the OnStar system properly responds to any command, the hardware is assumed good and the customer should be directed to the description and operational characteristics in published Service Information (SI) and the Owners Manual. They may also be directed to contact OnStar and be connected with the voice recognition group for assistance with system operation and tips. Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.