My pre-glow system isn't working. '83 300D OM617
This is the first time I have had any issues with the GP's. Functioned perfectly until a couple days ago.
Cold starts are challenging. I fear for the life of my starter and battery.

Dash light does not come on at all.
Bulb is good.
GP relay is getting 12V at main lead.
Relay's 80A fuse is good.
All GP's are getting equal power (10.9V) with key on.
I can hear the GP relay click off after ~30 seconds.
GP resistance thru harness shows four under 1ohm and one at 2.4ohms.

What else should I check?