I drive an 89 7.3 IDI turbo. I replaced the GPC and GPR. I've replaced all the glow plugs, and checked the continuity of the harness. All is well.

However, my relay won't stay on long enough to heat the plugs. Is there a relationship between the temperature sensors and the GPC? I can't find any information....

 

I know mine cycles in approx 1.5 second intervals, with about three in between. Gotta replace my plugs tho. Roll started and they stuck on for abt 5 mins before I got them off.

 

Well, apparently my temperature sensor wasn't the problem. I finally took it to a shop because a glow plug swelled in the head, and had to be removed the hard way. While there, they said that the controller had been wired wrong, and that cause the plug to over heat. I have a problem with that, because I wired it just like the previous controller had been wired, plus I checked the photographs on this forum regarding the wiring set up. At any rate, they got it straightened out, and now everything works like it's supposed to.

Thanks for responding to my post....