Glow Plug issues Please Help

[Cosmo12550]

I have a 94 GMC 6.5 turbo K3500. The original glow plug connectors had rusted away and were not working. The glow plugs were original, So I decided to install new glow plugs, new connectors and new controller. After install I noticed the new glow plug were not working. I took some voltage readings on both sides of the controller. battery side is 12v. glow plug side 11v. I disconnected the glow plug conector and took readings there (11v). So I am getting power to the glow plugs. I then ran a wire from the negative battery term. to the outter section of the glow plug. (glow plug was not screwed in) when I do that they glow. So, I think I have a ground issues. I assume the glow plugs should ground to the block. I checked varoius grounds to the block and test okay. Once the plugs are screwed in, how do actually know they work correctly? I mean theres know way to actually see/hear them work. I tried feeling for heat, but could not. Any help would be appreciated.

[Hubert]

You can check resistance from engine block to GP spade. Should be around 1 ohm. Clean the head and seat for the GP's and put antisieze on threads. You can always add another ground strap to motor and batteries thats one of the recommended upgrades for the gm trucks. If glow plug glows red fairly evenly along a good length not just at tip in your earlier test then GP is good. Recheck all wiring connections.

[moondoggie]

Good Day!

The glow plugs draw ~ 150A initially. Turn your headlights on, then turn the key to the run (NOT crank) position. While the glowplug light on your instrument panel is lit, your headlights will be noticeably dimmer.

Blessings!