The other day i stopped off at the store on the way back home, and when i came back to the truck to leave i turned the key and nothing. No clicks or anything. The radio and dash lights still power on when the key is in the "on" position. Took a screwdriver to the starter and it spun but didn't start it. Now i replaced the starter and turn the key to start and all I hear is a clicking in the fender at the relay. The fuel pump primes, the radio and dash lights turn on.The battery can't be dead, and power must be getting at least to the relay, how would I know if the relay is bad?

I also noticed when i turn the key all the way to the "start" position, the parking brake light comes on in the dash, does that mean anything?

 

If you bridge across the relay's big terminals, and it starts normally, that would indicate the relay is bad.

You can't do that to the starter - its solenoid has to be powered first to push the Bendix into the ring gear. So you have to first bridge the top big terminal to the small one. If it cranks the engine, the whole starter is good. If there's just a loud click, then add the lower terminal (be ready for a big spark). If it cranks that way, the starter solenoid is bad.

Read these captions:

. .

 

While you're at it, check your battery ground cable. They tend to corrode very badly at the intermediate ground point on the frame next to the fenderwell. When that happens, the system may still provide enough current for all the minor functions but not enough to turn the starter.

 

The frame ground tab is soldered/crimped around the UNcut cable, so corrosion there would interfere with bed/frame grounding, but not engine/starter/alternator.

 

It actually corrodes through the ground cable at that point and reduces the continuity between the battery and the block ground at the starter flange. That reduces the available current everywhere

 

If that cable corroded through there, all the other grounds would catch fire the first time he tried to start the truck, and then nothing would work at all. If it only corroded into that cable there, it would smoke & burn each time he tried to crank it, and the starter would spin slowly. Either way, it wouldn't produce this symptom: no crank, but everything else works. His problem is localized within the starting system; it's not affecting the entire truck, like a bad battery/frame/block ground would.

 

It IS the main battery/frame/block ground. It goes from the (-) terminal on the battery, to the ground on the frame, to the block at the starter flange. It makes no other connections. When mine rotted out it produced exactly the condition I described: all the low current stuff operated but the starter would not turn.

 

Where would i begin to look for it? Which spots would i check for current with my voltmeter?

 

Starter current will fry most meters
Set it to resistance and check for continuity from end to end of the (-) cable
You should get a very low number.

 

You check voltage with a voltmeter; an ammeter checks amps/current.

Put the black meter lead against the battery (-) POST (not the clamp around the post), and make it stay there. Put the meter where you can see its display, and move it as you move around.

First: remove, clean, & tighten both battery cable clamps.
2nd: check voltage at the relay's REAR terminal. If it's less than 10, repair/replace the red battery cable.
3rd: check voltage at the SMALL terminal on the starter relay while the key is in START. If it's below 10V, test the MLPS.
4th: check voltage at the relay's FRONT big terminal while the small one is bridged to the REAR one. If it's below 10V, replace the relay.
5th: check voltage at the starter's SMALL terminal with the relay's small bridged to the rear. If it's below 10V, overlay the red wire from the relay's front to the starter's small terminal.
6th: check voltage at the starter's TOP terminal. If it's below 10V, repair/replace the heavy red cable.
7th: check voltage at the starter's BOTTOM terminal (the one with the exposed braided cable) while the top is bridged to the small. If it's below 10V, replace the starter, or at least its solenoid.

 

i know you said the battery can't be dead. i think i would check it anyway. even if your meter shows proper voltage a load test may show otherwise.