Prc6913 Land Rover 300tdi glow plug relay
 

I've had very good results with this glow plug relay timer. It doesn't use an input from a temp sender to operate. Wiring diagram is easy to wire up. I use the glow plug output from the relay to operate a ford starter motor relay (firewall mounted type) as this relay can carry a higher amperage thereby keeping it out of the glow plug relay.

Interesting. If no temperature input, what does it use to calculate sufficient GP energize time? Does it do afterglow?

One of mine seems to eat the Volvo/Bosch GP relays. Do you have any links?