truck dies when i turn key to on position

is your starter turning the motor over, but the motor just wont run/stay running? if that's the case, then there is nothing wrong with the starter. you need a starter solenoid if your starter begins to be intermittent in doing it's regular duties... or doesnt do it at all. most just replace the starter as a whole.

Does your truck have the clutch start feature? Might be a bad clutch pedal switch causing the won't stay on symptom.

Since you have a voltmeter try disconnecting the starter's solenoid wire and hook the voltmeter to it. Verify there's 12 volts when you turn the ignition switch to the start position. Try jiggling the key as you start it and watch if the voltmeter shows a fluctuating voltage reading. If the fluctuation occurs do a continuity check of the wire harness of the ignition switch cable. As mentioned earlier the junkyard wire harness is possibly the culprit.

On my truck the symptom was driving on the road then like I turned off the truck and it starts to bog down. Then it starts up again with no help from me. I ended up buying a new wiring harness from the Mazda dealership after seeing that my ignition contacts were shot. This is the end behind the tumbler of the keys.

yea the starter is turning the motor over just wont stay running lol. and the electrical side of the switch looks fine which is the weird thing. and if need be i will go buy a new one and say f it. and everyonce in a while the starter will sit there and act like the battery is dead when its not i had the battery tested and it tested fine. we had it on the load tester for a good 2 mins all together and it was taking a charge.

cab: only thing is my truck is in neutral and i have my clutch pushed in continuasly while trying to start it so i know its not that lol.

Sure seems to be a switch issue from the comment above. Mine did the same a decade ago before I replaced my switch, would start but would then die just as I released the switch, unless I was lucky/careful...

might just have to suck it up and buy a new one lol. thanks guys. now i just gotta wait till i get my pay check and all the snow and ice melts till then fed ex wont ship anything. so its gotta wait which sucks but all well.

Check out the one(s) you have first, so you don't end up kicking yourself in the butt !!!

dont know for sure how to check em though. i dono whats spose to have power and whats not in what key positions.

Wow - because you state: "NATEF Certified Auto Engine Repair. i even have the certificate to prove it." in your signature line.

Basically: learn how to troubleshoot, or you'll just keep throwing parts at things and maybe sometimes get lucky. A 12 volt test light ($5) or a multimeter ($15) and a wiring diagram are all you'd need to troubleshoot. You'd have to remove the lower steering column cover for access, don't need to remove the steering wheel for that.