HELP Strange electrical issues

[83Diesel4x4]

Hello everyone, I am fairly irregular to this site as I own 3 fords and one chevy, but please dont take that as an "I hate chevy's" statement, because I love my suburban, but need your guys' help......


I have an 83 suburban w/ 6.2 diesel and this huge, and annoying prroblem:
[list=1][*]Headlights, Dashlights, Heater and electrical system in general is very dim[*]When you engage the parking brake, the whole system gets better (a lot better) but still not how it should be[*]Driving down the road Headlights flicker intermittently with no real rhyme or reason (doesnt seem relative to bumps ETC)[*]Glow Plug light comes on with this intermittent flicker[/list=1]

I am 95% sure this has nothing to do with the glowplugs, as they have been replaced and the controler has been replaced with a manual switch (and the suburban has done this since we got it, well before the glow plug controller change) and you can hear the audible click of the relay when they come on...its not happening, its just the light lighting up dimly and flickering (not bright like when you actually use the glow plugs)

I have a couple theories from an older thread on this board and one I came up with on my own:
[list=a][*]I heard about some grounding strap from pass. side head to firewall should I have one of these?[*]Or......Alternator problems?[*]Or......bad ground somewhere?[/list=a]

Any other ideas guys? please.....at my wits end

Kevin