ajb:

This is an electronic relay, so if it got wet it is probably shot.

Sounds like all the switches are working properly -- pin#15 is from the key switch (ignition on signaly), pin #31 is a ground for the thermistor (temperature sensor), and pin #50 is the starter energized signal (pin 50 is starter circuit). When the ignition is switched on, the relay should "click" as the contacts for the plugs closes.

You can "cheat" and get it going by making a "jumper cable" from heavy wire with and "alligator clip" on each end -- connect between the positive battery cable and the 80A fuse -- this will energize the glow plugs -- wait the usual time (30 sec?), the crank. When it starter, get out and disconnect the wire. Sort of a cludge, but better than no car!

What year is your 240D? There is one in the "you pull it" junk yard here, and I'd be glad to go look for the relay for you today -- I need to check for taillights for the Volvo again anyway.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!