You said recently having problems... did they work before? Did you make any changes right before the problem started?
Did you check the arrangement of the wiring? The TM contains a mistake and if it's wired up as the TM says, the glow plugs will not function.
The small orange wire, which tells the card that the glow plugs are receiving voltage, is supposed to be on the glow plug terminal on the relay, not the power in terminal.
Have you grounded out the terminal with the light blue wire to see if the relay closes? Start another thread for troubleshooting your glow plugs if these don't work...
Later,
Joe