Power antenna - Power antennas can develop a parking problem, i.e. they do not descend all the way, or consistently clunk during operation. Inside the power antenna mast is a plastic ribbed rope which is connected to cogs inside the power antenna motor. Either through moisture buildup inside the antenna from inadequate drainage, or plastic fatigue, the rope can break or lose teeth. New Mast and Rope assemblies are available through GMH dealers, be need to be fitted and retimed accordingly to ensure correct operation. Power antennas are controlled by a module, which is located on the left side of the dash, behind the glove box. The stereo triggers the module, and therefore the antenna will only stay up if the stereo is on. The module controls the height that the antenna will extend to, and this can be increased or decreased by the binnacle switch on the dash. The modules can be faulty, causing the antenna not to work, or to work intermittently. Modules are not all preset the same. Some may lift the antenna mast up to the limit, where as some may only lift them a few inches.
Power antenna mast and rope - Part number VS18188
Power antenna module - Part number 92029494