Glowplugs

[buckles24]

Out of curiosity is there anything else that might make glowplugs not function properly other then the GPR and the Glowpugs themselves both are fairly new in my truck and when I changed them a few years ago didnt make much of a difference also the ole girl is tough to start in anything less then 60*. Not stupid hard just requires more turnover time then normal IMO. A side note I will be getting the GPR upgrade here soon.

[superduty4x4]

You could have a wiring problem that isn't allowing the GPR to turn on.

[buckles24]

yea i will have to test it or have someone test it i was just wondering more along the lines if there are any other sensors or such that are tied into the system

[superduty4x4]

Nope, PCM to GPR to glow plugs.
On second thought, the amount of time the GP's stay hot is tied into the ambient air temp I believe, but a bad IAT sensor wouldn't cause the GP's to not work at all.