Ford f100
https://www.garysgaragemahal.com/1980-evtm.html
I assume your truck is a 1980, what engine is in it ?
I assume you have made sure all the electrical connections are corrosion free ?
I find my local NAPA can get most wire connectors, I'll assume other name brand auto parts stores can too. Most will tell you to buy local and don't buy the cheapest part you see.
I would first start at the battery as that is where power for lights start.
Make sure the ground side is good. Battery> motor> to frame. You also need a 10 ga wire from the motor to the fire wall to ground the cab.
It also would not hurt to add a ground from bed to frame so it is grounded.
I would pull all the fuses and if they look bad replace. If you reuse them clean the metal part of the fuse before you put it back on the fuse box.
There is a plug under the brake booster that is from the main harness to the rear harness that runs along the frame. There is another plug at the left rear from the frame harness to the taillight harness.
Pull them apart, mainly the taillight plug, to make sure they are clean.
Being the brake lights are out I would look at the switch. Dose the switch have power in to it all the time and if the pedal pushed power out?
May want to recheck the taillight bulbs and sockets to make sure they are good.
You also say brake lights went out again do the turn signal lights work front / rear? What about 4 ways?
On the dash lights I bet they are burnt out and the colored caps frosted. What happens when you turn the head light switch left & right a few times anything?
I would replace all the bulbs and clean the socket contacts on the cluster and go from there.
Dave ----
then multiple ground wires are joined together half way in between, you will notice a lump in the harness.
tween.
This was an issue with mine and some crayz stuff would happen.
Then the dash light problem ended up being a ground wire between the intake manifold and the cab.
The taillight harness with a different way of grounding the taillights was changed on later year bullnose but I am not sure when.
Here's the 81's I couldn't load the 80. Oh, I see the EVTM for the 80 is a little different in the way its loaded.
https://www.garysgaragemahal.com/grounds.html
then multiple ground wires are joined together half way in between, you will notice a lump in the harness.
tween.
This was an issue with mine and some crayz stuff would happen.
Then the dash light problem ended up being a ground wire between the intake manifold and the cab.
The taillight harness with a different way of grounding the taillights was changed on later year bullnose but I am not sure when.
This is why I said to run a ground wire from frame to the bed somewhere as the frame should be grounded from the factory.
Later year trucks had a ground wire from the tail lights to inside the cab behind the radio on the firewall and why the cab has to be grounded.
Also from motor to cab to ground the cab as the motor was factory grounded.
Dave ----











