ignore the light on the dash, it's useless.
45 seconds is correct time.
are you touching the tip of the glow plug out of the car, or the screw terminal on the glow plug that's in the head of the car? glow plug out in your hand, and warm to the touch, bad plug. wire terminal warm to touch after warmup, normal.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!