1982 720 diesel afterglow timer bad?

[scrapman1077]

Once I turn on the key, the glow plug dash light flashes for only a second, I have replaced the relay and you can hear it click. Do you know how I can test the afterglow timer? The truck will not start without a shot of starting fluid, The dash lite used to stay on for the entire cycle, you could hear the relay click off at the same time the dash lite would go out. Now the glow plugs don't get hot, this is why I changed the relay, but I would like to nail down the issue rather than continue to change parts hoping to fix the problem.