Ok! Here is a glow plug activation and light issue, My1979 300TD has suddenly failed to activate the glow plugs and illuminate the glow plug light in the dash when the ignition switch is in the "glow pug" position but will activate light and glow plugs when the stater is cranking! The glow pug relay seems to be fine, It clicks loudly when the ignition is switched on and off plus the fact the pugs and light are activated again when the starter is engaged! While troubleshooting in the engine compartment I found a major vacuum leak in one of the rubber three way splitter. So can a low vacuum condition affect the ignition's activation of the glow plugs? Has any one experienced this issue and what was the solution?
Thanks for your help