Confusing Electrical Problem 86 22R
 

Likely a couple issues in here... There are some similar threads I've found but, these issues seem to be connected in some way.

Problems:

1. Charge and brake light stay on​​​: The two indicator lights stay on very dimly even when the parking break is disengaged. I have checked that the break is hitting the switch under the dash. I am fairly sure the battery is charging. I have not done a definitive test, but the alternator does magnetically attract a screwdriver, and the truck starts fine as long as I drive it every day. Brake fluid level is ok. I have read about the fabled CHARGE LIGHT RELAY. I located an empty plug under the kick panel on the drivers side that says "CHARGE LIGHT RELAY" but there is no relay there, just a 5 pin outlet style plug. I will be testing the alternator and voltage regulator more thoroughly, but these lamps have been on intermittently for about a year now. Never had a problem starting until I left the truck sitting for a few weeks while out of town working. Anyone have any advice here?
2. Battery loses charge: Lasts overnight, but after two or three days I can't start and it goes from cranking to just the solenoid clicking in a 3 or 4 turns of the key. I get 11.75V across the terminals. I disconnected the grounds at the block and body and I get 6V when I check the NEG terminal to bare metal. I pulled all the fuses and found that when the DOME fuse in the driver side box is pulled it drops to about 4V, and the same thing happens when I pull the 40 AMP fuse (fusible link?) next to the battery. I have a small (10-12 gauge) wire coming from the engine block ground wire to a round plastic connector that leads out of a hole in the body. When that is unplugged, and all of the grounds are unplugged I get a full 12V from the NEG terminal to bare metal. I feel like I have some slow leakage in possibly a few different circuits. Where should I go from here?
3. Headlights and Braking Lights have issues: 6 months ago my drivers side head light would come off and on. I cleaned and replaced battery terminal clamps recently and while that seemed to help get better starts, now, I have no headlights or brake lights. I will be testing for power at all these components tomorrow, but it seems related to all this mess somehow.

One BIG question I have is... My truck is old, and I pay pretty close attention to it... All of the electrical is ANCIENT... Would anyone have any recommendations as to what I can remove, what I can upgrade (like the halogen hea

It is quite possible something is grounding back through the brake light and charge light.

The best place to start is to make sure the battery terminals are clean and tight.

If your truck has never had the battery cables upgraded now might be a good time also the wire from the Alternator B terminal to fuse block

Just doing this might cure your electrical issues .

It could be contacts are fused in a relay causing you slow battery drain

It might be the battery itself just no longer will hold a charge over time

If you have a Charge Light relay was your vehicle built for other then a USA market??

My 86 Does not have one. Perhaps you don`t have a 86??

The 1986 does not have a Charge Light Relay.
Do as Wyoming says above and ensure that your truck's power circuit is restored to stock as shown below. We could be thousands of miles away from you and we do not see what's right in front of you so we could not effectively troubleshoot a modified wiring. There is no point in "upgrading" a butchered wiring.
Make sure you have 12Volts at all times at points in red rectangle on left side of IGN switch, and 12V at points in red rectangle on right side WHEN corresponding contacts are closed.
Attachment 112235