Hello all. I just changed 6 of my 8 gps out on my 85 f250 with the 6.9. I was not able to get to the rear two becuase of the turbo kit being mounted in the back. After these were changed, I wired a switch for manual control up and tested all the connections with a digital meter. Ive got power from the switch to the relay, then from the relay to the plug harness. But I'm very positive the plugs are not turning on when I hit the switch. Its got 12v DC going to the harness. Now remember those to I couldn't change, I'm using ac 60gs since its a manual system. I left those two connections undone since they are still factory and cannot stay on long like the 60g plugs can. Would that be the reason that my plugs wont turn on or do I have a glow plug harness issue that I need to track down? I plan on pulling the motor and doing a rebuild on it as well as injectors, redoing my glow plugs, injector install kit and what not. Would I be better off doing a homemade glow plug harness since I have the manual switch system? Any help would be greatly appreciated. Thanks guys.