I am replacing the rear air-assist struts on a 1991 coupe deville, and have completed everything except the last step. My manual says "pressurize the suspension system by grounding the compressor test lead in the engine compartment for several seconds to allow the struts to compress slightly. Do this before lowering vehicle to the ground." There is no indication anywhere in the manual about where this test lead is on the compressor, or how to ground it. I know where the compressor is but need more info about this test lead. Any help would be sincerely appreciated. Thanks.