First thing to do is check to see if the plugs are getting power. No power,
no heat, no start. You have to VERIFY they arent getting power, dont just
use your intuition. ESPECIALLY since you are slightly less than stellar on
the subject. Once you have verified that they arent getting power, find out
if the controller is getting power. The relay and timer, is combined to make
a controller. If you go to www.autozone.com, you can actually look up wiring
diagrams. They dont have the 6.9L listed, but I am willing to bet the 7.3L
diag is almost identical, so the wire colors should be the same. Are you
sure this isnt a 7.3L?? Anyway, you will find that if no power is getting to
the controller then, no power will get to the plugs. If you want to just
bypass the whole system then you can do like the fella mentioned above, and
wire in a push button for your plugs directly, but make sure you fuse it
with maximum a 30A fuse. Personally I would go get a 4-pin relay (30A) and
use the push button one a 5A wire to actuate the relay, so that you have
less chance of screwing up your glowplugs. Run one wire from your starter
solenoid to the pushbutton (put the fuse as close as possible to the
solenoid), and run another wire from the button to terminal 85 on the relay.
Run another wire from terminal 86 on the relay, to a ground. Then hook
terminal 87 up to the battery with a 30A fuse. Run terminal 30 to the glow
plugs. All should be well in your little world. You might double check on
the amperages, the plugs might require more, but the I know the fuse for the
button (5A) will be sufficient to operate the relay.

Pk