96 gmc 6.5 problems starting
 

after sitting for a few hours i go to turn it on and no glow plugs or lift pump comes on. let ignition stay on for awile then starts acting. its not the pmd for sure already replaced and have 4 others on hand that i've switched out and tried. Could be icm? or ecm?

Did you check your gpr?

Ignition switch is failing.

that is what im thinking. but today it was doing it i unplugged pmd while key still on plugged a different one in and glow plugs and lift pump started engaging. unplugged that pmd still functioning glow plugs and lift pump. plugged in original pmd and still worked fired right up and working ever since. probably gonna do it again in the morning. could have been just it started working right when i did that so just coincidence.