hello! ive got a 1992 and i cant seem to get it to hold a charge.. now i been working on my little truck long enough to realize it is an electrical problem. but heres the kicker. under my hood coming from an unknown wiring harness is this random red wire not connected to anything and not putting out any energy (checked with a voltemeter ) as long as i drive the truck at least every 24 hours it will start up no problem but if i leave it sit even for just a day it dies..i need a dummys guide to solving this mystery it really is kinda frustrating..

 

A good clear pic of this wire might help identify it.

As to the battery not holding a charge, its either not properly charging, your battery is on its last leg, you have something drawing excessive power with the ignition off, or a combination of all of the above.

I'd start by pulling the battery, fully charging it, then having it load tested. Once you eliminate the battery as a possible cause look at the charging system and associated cables.

If you're handy with a voltmeter you can do some basic test to help identify potential problems with the charging system.

Note: all tests should be conducted with a fully charged battery and ensuring all fuses have tested good.

1. On Vehicle Test – No Load Test
Connect the voltmeter’s positive lead to the B+ terminal on the alternator and the negative lead to ground.

Ensure all electrical accessories are turned off.

Start the engine and maintain 2000 rpm, check the voltage reading. It should read between 13.0 & 15.0 volts.

2. On Vehicle Test – Load Test
Connect the voltmeter’s positive lead to the B+ terminal of the alternator and the negative lead to ground.

Start the engine, check the voltage reading and write it down. This is your base voltage. Next turn the A/C on, the blower motor on high speed, and the headlamps on high beam.
Increase the engine speed to 2000 rpm. The voltage should increase at a minimum by 0.5 volts above the base voltage.

If the voltage increases as specified the charging system can reasonably assumed to be operating normally (Per Ford Service Manual).


3. On Vehicle Battery Cables/Connections Test

Positive circuit test – Connect the voltmeter’s positive lead to the B+ terminal of the alternator and the negative lead to battery positive terminal.

Start the engine and maintain 1500 rpm, check the voltage reading. It should not exceed 0.5 volts.

Negative circuit test – Connect the voltmeter’s negative lead to the alternator housing and the positive lead to the negative terminal of the battery.

Start the engine and maintain 1500 rpm, check the voltage reading. It should not exceed 0.5 volts.

If either test exceeds .5 volts look for signs of a bad connection between the two points, i.e., corroded battery terminals, cables, ground connections, etc.

Check system for excessive power draw – You'll need a meter capable of reading DC current rated at 10 amps or more. Otherwise you may damage your meter.

Disconnect the positive battery cable. Connect the meters positive lead to the battery positive post. Connect the meters negative lead to the batteries positive cable end. Write down your reading and compare to the manufacturers specifications. Generally anything between 20-50 milliamps is normal.

 

Note on #1
A reading over 15 volts indicates an overcharging problem.
Overcharging the battery can warp the internal plates causing them to short. This is also known as "cooking" a battery. This will ruin even a new battery.

 

i have had both the battery and the alternator tested what it sounds like to me is that i need to go ahead and invest in a voltemeter and spend some quality time with my trucks electrical system im pretty sure that it is because something is drawing power out but this post on overcharging may be a possibility also see as yesterday i found my battery wire connectors almost completley melted on the bottom gahh so it look like i just need to sit and figure all this out thanks for the help guys i will more than likley be doing this during the weekend and will post results. :)