85 K5 6.2 Diesel

first let me say i'm pretty new to working on engines and whatnot, especially diesels, so please forgive me if i miss things that may be obvious to the rest of you.

ok, here's the problem. my truck will not start, inconsistently. it wouldn't start a couple weeks ago, then one day i tried it and it was fine. i drove it for a week, now it won't start again. when the key is in the "on" position, the dash lights up and i hear the door buzzer like normal. when i turn the key, nothing. no cranking, no clicking.

also, here's some background information that may or may not be related. i just got the truck last fall. i noticed that the "water in fuel" light was on and figured i should take care of that before the weather got too cold. i pulled off the fuel filter to drain the water (i know about the valve now, thanks). i didn't have any diesel to prime the filter and wore down the batteries trying to start it back up. i recharged the batteries overnight and got it going the next day. a few days later my batteries were dead again. this time, it seems the rubber coating on the positive battery lead had worn through and was sparking off of the frame. i fixed that and had the batteries tested. one was trash, the other would be soon, so i replaced both.

i'm wondering if perhaps i kinda killed the starting by cranking it so much with filter replacement and dead batteries. also, a friend told me that sometimes the tumblers in the ignition get worn and don't make the connection to start the engine. is this possible? any tests you got for me to narrow down the problem? recommendations on where to get parts?

thanks in advance.

 

it's possible that the ignition switch is worn out. have you also checked the cables at the starter and ground? it's also possible that the starter motor and/or solenoid is shot.

 

so, take a multimeter and test for voltage at the starter? if there's no voltage, likely the ignition switch. if there is, then it's gotta be the starter. am i understanding this right?