i recently replaced the tranny in my f150 from the t170 to a 1980 f150 t18,the truck started fine with no problem before the swap but now my truck wont start unless its jumped. all my lights are fairly dim too any body have a clue please help

 

Check your grounds. That would be the first place I would start.

 

Yeah, what bilt28 said. Check & clean all of your major electrical connections at the battery & block.

 

so i checked the battery with a volt tester and it was getting 13.5 volts and then i checked the + goin to the sylinoid and it was gettin 13.5 volts. so i had my wife try to start the truck and i checked the volt from the sylinoid to the starter and it was only getting 2 volts. i replaced the sylinoid and tried againd and still only gets 5 volts to the starter,its weird when i try to start it the sylinoid makes a funny almost clicking noise please help

 

That clicking noise happens when inadequate voltage is present. If your battery has 13.5
volts, that's good, and you seem to have narrowed down the loss to the cable between
the solenoid & starter, but...

The solenoid shouldn't click with 13.5 volts at the battery.

My first recommendation is to go clean ALL of the heavy-duty connections - between
battery and both cables, make sure the terminals are clean & secure.

The negative wire's connection to the engine block (and sometimes frame, too) is equally
as important, this is the return path for the starter circuit.

The starter itself grounds through the case to the engine block, make sure grease &
whatever haven't infiltrated that junction.

If all that still fails, well, you've already found the loss and all other connections are
(hopefully by now) known good & solid, so a new cable would be in order.

Some of those solenoid <-> starter cables have got copper clamps on them and the
underlying copper strands are exposed to the elements (or they can become exposed
because of breaks in the insulation).

Copper corrodes, it turns green and a white, powdery substance develops over time.
This causes resistance in electrical flow.

This might help:

https://www.ford-trucks.com/forums/1...t-need-it.html

 

ill have to give it a shot tomorrow ive checked cleaned and tightened every thing i could think of and now the truck wont even try to start the starter wont engage at all,before it would try but real slow