No start 2000 jetta tdi

Ok so.....i recently change my fuel filter did all the normal line bleeding. The next morning the car would turn over and no start.
So I got out my books and did trouble shooting and I boiled it all to to this......if the glow plug Indicator does not come on in the dash, the car doesn't start. It has appeared at random times during my trouble shooting gand the car would start. So I check the shut off solenoid at the pump for voltage and there is none when the glow plug indicator does not come on. But there is voltage when it does come on.
So my question is what is causing this electrical issue. I am beginning to think the ecm or faulty wiring some where...
Any thoughts????

Relay 109 most likely

If the glow plug light does not come on and your car just cranks and cranks. Change out the 109 relay as Kyle has said. It’s up under your steering wheel, over top of your shins as you are sitting in the driver seat. There is a relay panel there. You probably still have one of the old black relays, the new ones are grey.

Thank you for your help. I'll try it out.

At warm temps the plugs don't preglow. GP light only comes on momentarily when key is turned on.

After a few seconds the fuel solenoid drops out if the engine isn't started.

Be aware of these during your troubleshooting.

Yes, cause it sorta sounds like air intrusion in the fuel, not 'lectrics. Perhaps the thermo-tee or o-rings, or one of the fuel lines are damaged. Once you find and fix the air leak, if in fact that is what it is, you may need a another quick bleed.