Acert C15 Clicking no start.

Likely a starter relay in the fuse box with burnt contacts.
"Found Ignition relay and bought new one still nothing" Where was this relay? Did you replace a relay that was clicking? How do you know what it is for? If you can hold your hand on where the clicking is coming from turn the key and try to start the truck to find the exact spot of the clicking. Clicking can be caused by 2 things 1 - bad internal contacts on a relay that are burnt and won't stay closed 2 - not enough voltage due to loose or corroded cables, either externally, internally or both. Cables can get internal corrosion that can't be seen. Only way to find out is to do voltage drop tests. Multimeter set to DC volts with + on one end and - on the other end of the cable and turn the key to crank. Drop should not be more than about .2 - .5 volts.

 

Really need a wiring diagram., may be a module involved. Goodysnap on this forum should be able to get you one. Starter is definitely good as it turns over. The starter solenoid post that you put power to, check to see what voltage is there when the key is turned to try to start. Voltage drop can be checked on both the positive and ground sides Never hurts to check all fuses. Find a good video on youtube, plenty of them. Check drop between starter and batteries. A methodical process checking multiple points to find where the problem is.
Here's a good one that explains it. Same on heavy truck as a pick up as long as 12v system.
Ford F-150 No Crank No Start: Engine Starter Motor Diagnostic Walkthrough! - YouTube