Battery discharges overnight. Put in new start relay, starter and battery. Also put in new ignition switch but it might have been defective, when I removed key (lock position), the dinger alarm kept going off for a few seconds. Put the old switch back in, charged battery (load test was okay) and truck started (The voltmeter reading on dash gauge was less than 8 volts ! Turned off truck, went out a few hours later and turned key, nothing happened. Any ideas guys?

 

If the volt meter was reading 8 volts, then the alternator is not charging. Start by hooking an ammeter (or a multi meter that can read current) between the battery and a battery terminal. Start pulling fuses 1 by 1 until your current draw goes away. This is with the key off.

 

That's a big draw. My guess is alt is bad. Charge the bat, see if alt is getting warm with key off. Or you can unhook the big cable on the alt, then touch it back on the stud with the key off, if you get a spark, alt is junk.

 

I'm going with, this is an '88 and likely has the infamous 2G alternator.
No stud to 'touch' the cable to, but a rectangular plug with two black/orange charge wires and a white/black stator wire.

Ford TSB 96-21-4 spells out why this connector should be changed any time you have a charging system issue.
Yes, it could be the diode board inside the alternator causing the draw, but usually the alternator will charge while running.

In this case he has no charge *and* substantial draw (key out)

Chasing a dead battery had me changing this pigtail twice in my truck before I finally got smart and did a 3G conversion.

 

Definitely going to check into this today, yeah the plugs on the alt don't have anything to attach a meter to. I'm assuming a "3G" alternator has different hookups ? I'll see if anybody at my local O'REILLYS has ( or knows ) what I need.

 

The 3G alternator went back to a charge cable stud because of all the charging mysteries and alternator fires with the 2G harness.

You need a fused charge cable, and some wire fittings -or- the inexpensive conversion regulator plug available on eBay for around $10

 

If you remove the negative battery cable off of the battery hook up a test light (non LED) between the negative post and the cable. It will light up for you if there's a draw.

If you pull and replace the fuses one by one in the fuse box the bulb on the test light should go out once you pull the fuse for the circuit that's causing the draw.

That should help you to pinpoint what might be causing the battery to go dead. I had a hood light killing my battery years ago, I was going crazy for weeks and this was how I found the draw.

Hope this helps out

Tony

 

For the advice and suggestions from you and others. Good to know people are still willing to help out these days.