I took the brown/white wire coming off the PCM (2005 5.3L engine) and wired that to one side of the light on the dash. The other side of the light was wired to a 12V feed. When I turn the ignition on the light never comes on. Shouldn't it come on upon startup? The only time the light has ever come on was when I tried to start the engine with a weak battery. It came on and only went away when I charged the battery and started the engine. Any help getting this to work will be greatly appreciated. Thanks.