Just put a good 1985 6.2 (J) military engine in my 1985 chevy truck....when turn switch on; most of the time the glow plug light does not come on ....if I move or wobble the glow plug controller relay connector it will come on ......what can I do to fix this ?? (Thanks) :help:

Check out the sticky for glow plugs. I would wire in a manual glow plug switch. You can replace the controller, that is probably where your problem lies.:grd: