And here's the proof that a picture is worth a 1000 words -- without further ado:
The back story. Back in the mid-90's a bunch of us car enthusiast types started going to either the Spring or Fall Carlisle car shows. Word-of-mouth had it that the show covered ~70 acres down in Pennsylvania, and you couldn't see everything for sale in 3 days. (!) So we decided to see for ourselves. Due to the laws of supply & demand, the hotel rooms were sky-high...but we found a cool little campground with hot showers & within walking distance. So we literally camped out, and after it was all said & done we managed to stay for ~$15/night, per person.
Anyway, I went down in order to help my buddies spend their money, so my guard was down. Midway through the 2nd day, a super-clean rust-free, stone stock '86 Mustang convertible was behind a bunch of other stuff. Walking up to it I figured that it had to be an automatic (like most convertibles)...but lo & behold it was a factory 5.0/5-speed.
And the price was good. Almost too good to be true. If it had been an automatic, nothing would have happened...but in a moment of weakness, it followed me home. It drove great, no vibration, no smoke, no overheating, it just ran. So I got it back to VT no problem. Was busy at work, so it took maybe a week to get the VT title, registration, & plates.
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So, right after I put the plates on it, tried to start it...and nada. The battery was flat. The battery looked pretty new, so I cleaned the connections & recharged the battery. Car then started right up, and down the road I went. But as time went by, the car seemed to suffer from an 'intermittent' no-start problem? Hmmmm, I wonder if this has anything to do with the really low miles (that checked out) and that really good sales price?
Of course, one of the first things to do when troubleshooting an intermittent is to see if there is any pattern to be found, or is it truly random?
Pretty quick I realized that if I drove the car every day, it always started. Even if I drove it every other day, it would crank over a little slower, but it would still start. But if the car sat for a long weekend, no joy. So then I wanted to figure out if the problem was within the battery itself, or was it the car? (BTW, I was hoping for a self-discharging battery.)
So then I started driving the car with a wrench in the glove box. After I got done driving it for the day, I would pop the hood, grab the wrench, and disconnect the + lead from the battery. Several days later I reconnected the battery, hopped behind the wheel, turned the key...and it started *immediately*. Eff me -- something in the car itself is discharging the battery, even when the key is off. (EDIT: In this case, the battery was the Victim, and the car was the Perpetrator.)
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The beauty of the power distribution in modern cars is that each electrical load is on it's own circuit. So to troubleshoot a parasitic current draw, all you have to do is disconnect a lead from the car battery, and install an ammeter in series. If there's a problem, it should show immediately -- too many milliamps being drawn as a constant drain = battery drained flat too soon.
And then if you don't see something obvious (like a courtesy light in the trunk staying on, or a large stereo amp never shutting off, etc. -- all you have to do then is pull fuses, one at a time, and once you pull the fuse where the current draw immediately stops, you now have the problem narrowed down to something on that circuit.
So that's what I did. And sure enough, there was excessive current draw immediately when I put the ammeter in series with the wiring harness. The only problem was that the problem was affected by too many circuits? WTF? Electric door locks, electric windows, convertible top, the horn, the headlights, even the brake lights? The fuse box was in good condition. (Previously in a used Honda Civic the fuse box was corroded beyond belief...turned out it was one of those 'flood cars' -- luckily ebay offered up a spotless replacement fuse box for 30 bux.) After careful scrutiny under the dash, there just seemed to be too much wiring -- way more than expected?
Finally, we found a mysterious control box with all kinds of wire coming out of it? We found a part number on it...googled it, and discovered that some unknown previous owner had an aftermarket anti-theft alarm/disabler security box installed. All the problem circuits were supposed to be monitored, and if excessive current draw happened, the box would detect that as some perp was trying to the steal the car, the lights would flash, the horn would blow, etc. Worst of all, it was all installed slap-dash
using vampire taps - Yikes!
It was bad enuf that I knew the damage couldn't be undone properly with the wiring harness installed. So that winter, out came the dash & the entire wiring harness. Every single vampire splice was removed, and whenever possible a new piece of waterproof heat-shrink was applied. And if we couldn't get the heat shrink on due to the way the harness was made, then we would snip the wire in 2, slide the heat shrink down one side, strip the wires further, clean & reconnect everything mechanically solid using a Western Union splice, solder the splice for a permanent fix...and then slide the heat-shrink over the entire site & make it weatherproof.
It sounds like a lot of work, but once you got rolling we had the harness completely repaired in 1 long day, with many celebratory cold snacks
after we were done. All told, it was almost 2 days taking it apart (documenting/leaving ourselves written bread crumbs while working at deliberate speed), a day to undo the aftermarket alarm damage, and another day to re-install it.
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After all that, it simply worked. The car started, whether it sat for 1 day or 3 weeks. Just like a new Mustang.
That's all I've got to say about that.
3D gump
