I have a 96 vw passat tdi, I have replaced the glow plug relay 50 amp fuse under the cowl and still no power at the new glow plug harness. Now the glow plugs in the water jacket work, is there another relay besides the one under the cowl and the 108 under the dash that control the glow plugs? If there is... where can it be found or is this a wiring issue?

SOURCE: volks wagen golf diesel tdi Nreg

Check the glow plug thermo sensor...found in the cylinder head.
Unlightly anything wrong with injector pump.
Good luck
John

SOURCE: NO POWER TO GLOW PLUGS

I have a '98 Jetta diesel that had problems with the glow plug circuit. I ended up replacing the harness and a fuse. All the information I needed to know I found on this web page:

http://www.tdiclub.com/

You will have to sign up to post questions, but it's free. I've had many other problems as well and found the experts there very willing to work with you.

Tom

SOURCE: 2002 Jetta TDI check engine light

very common for the harness that plugs onto the glow plugs to have too much resistance it will still work but will set codes

SOURCE: my 1997 F-350 powerstroke keeps blowing a 30 amp maxi fuse

I changed the glow plug controller selinoid haven't any problems since Thank You!

SOURCE: MY GLOW PLUG LIGHT IS FLASHING IN MY DASH BOARD VW

Despite what you may read from other comments....The glow plug light is simple a multi function warning light and IS among many othed things in fact used to warn of brake light and brake light switch failure. Therefore it can NOT be treated as glow plug problems only.
I have worked on V.W for many years and have encountered this problem many times. You should get the OBD codes read. This will reveal the exact problem...and there may be more than one
You can contact your V,W agents if you wish and check to see if I am correct.
Best of luck
John