So we have 3 stages to glow plug heating. 1st stage is pre heat, this is in the region of 10 Amps per plug heater, 2nd stage is during cranking, now on an engine that has sat for 4 hours after running on mine this measured 7 amps per plug heater (as the module knows the temperature of the engine from the ecu water temp sensor via CAN and adjusts heating), then there is a running current that is only on until the engine reaches a pre set temp or time period to aid smooth idle when cold and during warming up.
So below is a couple of pics.
1) 60 amp fuse for the glow plug module/heaters
2) this is the module, left connector is data, right connector is the 5 wires that go to the plug heaters, and far right is the power cable from that battery fuse.
Here's a vid I did of the pre heat and cranking: https://youtu.be/zH0ei1uHTBA
You will see for pre heat OL (Overlimit) is on my meter, my meter reads up to 40 amps dc, this would be around 50 amps though and only lasts a few seconds, next you'l see the meter start to shake lol and 35 amps, this is the cranking stage, I didn't do running stage but if the engine had been stone cold it would have shown a further heating period.
What I will do is repeat this again in the morning with a cold engine and post up a video of what happened.