I have had a look through several threads, but when asked , everyone has 12v at the glow plugs buzzbar.

My TD42 (1993) wont start when cold, but is fine when its warmed up. When I turn the ignition ,the glow plug light comes on , I can hear a relay clicking on , and then off after a few seconds, then back on. I assume this is the glow plug relay ( furthest forward under the panel between the front wing & the battery) , but I have 0v at the buzzbar. As a test, can i simply run a lead from the + battery terminal to the buzzbar and see if the car fires up ?? I dont want to blow anything up.
The starter motor turns like a good'un so it must be the voltage to the glowplug bar...right??

Any recommended and easy to follow checks will be greatfully appreciated.