Check engine lite produced a glow plug system DTC. Glow plugs check satisfactory; glow plug relay (104) checks satisfactory. Glow plug fuse (50amp) checks okay. Battery voltage at pin 30 on relay checks to 12 volts. Glow plug lite comes on momentarily with key to run, as normal, but no actuation of relay to put voltage to glow plugs. Door open switch, actuated on and off seems normal. Can't find much information on the automatic glow time control module (supposed to be behind the instrument panel) or even if this car (1997 vw jetta diesel) has one; VW Parts had no clue about where or what it is. Obviously, there must be some method to time glow plug actuation below a fixed ambient temperature. Don't want to jump into dash without "more input" information. Any help is appreciated.