"Fixing" the Truck

I went to take the trash to the dump a while back and discovered my truck would not start. It was obvious from the sound that the (brand new) battery had drained away. A jump start got it going again and it started up okay the next day, so I just figured I was a bonehead and left a light on somewhere in the vehicle that slowly killed the battery in a non-obvious way.

After the truck had sat for about five days I needed to take it out again and, once again, the battery was too weak to turn over the motor. Obviously, I had an electrical problem.

Now, vehicles and computers are just tools to me. I get only minimal pleasure out of them when they are doing their job, and I just don't care how they work. Oh, don't get me wrong... I know quite a few programming languages and I once taught myself enough car stuff from scratch to have successfully single-handedly rebuilt an engine from a 1965 Corvair.

So you see, “I don't care” isn't sour-grapes code for “I don't like things that are hard to do or are outside of my elitist comfort zone”. I can and do learn. It's just that I simply and truly don't care.

When someone excitedly tells me about the features of the new 2011 Ford Whatsit or extols the virtues of their video card that can actually play Crysis without needing to be submerged in liquid nitrogen, it has the same meaning for me if they were passionately describing a crescent wrench or a pack of sandpaper for some reason. I am glad the topic gives them pleasure, but, to me, its just a tool.

But, like all tools, it is a hassle when they break when you need them and that's where my “I don't care” attitude stops being a reasonable thing to do. Time to go marching up the learning curve yet again.

So I fired up the Kindle and tried to find a Haynes Manual for my F-150. Shut up. I know dragging a fragile piece of techno-bling out into the cold, greasy, dirty, and possibly wet environment you are going to encounter while troubleshooting an auto problem is a bad idea – it was sitting there and I just wanted to see what the price of the book would be through Amazon.

No Haynes car manuals at all. Huh. Oh, wait, it's just showing the downloadable content, not the paper stuff. But, wait, what's this? A Haynes manual for the USS Enterprise. The starship, not the aircraft carrier. Interesting, but that doesn't help my truck issue, it only helps my “I haven't said 'oh you've gotta be freaking kidding me' in a while” issue.

I got the book ($20) at an auto parts store in town and headed home. If you have never opened one, here are a few observations about Haynes manuals:

1. They are wrapped in plastic. At least they are at the auto parts store. I guess this is to prevent people from coming in, looking up the answer to their minor car problem, and going home to fix it without shelling out twenty bucks. Personally, I think that sucks.
2. The writers of the book are heavily into coarse, semi-accurate generalizations that assume you were really paying attention when your father took you out into the driveway on your twelfth birthday where the two of you bonded in a Rite of Manhood by ritualistically dismantling and re-assembling the family car. What? He didn't? Well, then ya maht as well be wearin' a dress, then, Nancy-boy. Find the Generic Electronics Module yourself, cuz we ain't helpin'.
3. God help you if you have an electrical issue and you don't have a degree in Electrical Engineering or several decades of automotive or electrical experience. It is clear the price of ink must have gone through the roof just as Haynes was about to print out the electrical schematics, forcing them to render the description of the various wiring harnesses and everything they connect into a single haiku. Well, not really, but the minimalist drawings could be a hell of a lot more helpful.
4. The Index is for display only and lends a “finished” look to the book. It is not for looking things up.

I figured I would start by removing the passenger compartment fusebox cover since I had already performed the requisite “ten minutes of staring blankly into the engine compartment” before I went to get the book. I just happened to brush the back of my hand against one of the relays as I was doing this and it was very warm to the touch. Hmm. I let the truck sit for about 15 minutes and touched it again.

Still warm. Well, that shouldn't be. I knew from the amount of time it took to kill the battery and the fact that the alternator charged up the battery just fine that the electrical short was a minor one, maybe an amp or two. The ironically named Battery Saver Relay itself tested fine – there just always happened to be 12V across the coil, regardless if the glove box light, the hood light, or the map laps were on or off.

With the relay pulled, the battery drew about 60 milliamps, which, I guess, is the right amount of current to provide standby power to the onboard computer and to the little blinky “THEFT” light on the dashboard. With the relay in place but nothing on or open, I was drawing about fifteen times that much – the right amount to drain the battery in a couple of days. The same thing happened with the replacement relays I got when I went back to auto parts place, so the relays were not the problem.

Some more poking around narrowed the problem to an output line of something called the GEM (or maybe the Central Timer Module.. it's a little tough to figure out what the Haynes schematic means here... ).

The Internet speaks of the GEM (Generic Electronics Module) in hushed tones as is right for something that takes authorized Ford dealers upwards of $500 worth of pixie dust and unicorn tears to fix (labor not included). I expect there is a bit stuck low controlling the output of the line connecting the Battery Saver Relay to the GEM which is causing the battery to slowly drain to ground, or the line itself has frayed and is partially grounded.

Either way, that's like $300 worth of labor to have found and fixed. I would try it myself, but, since I would have to remove the fuse box to get to the problem (FWIW, I found the location of the GEM on forums out there, not in the differently-useful book). The Internet tells me it's a tricky thing to do and its not a task for the unqualified.

Fair enough. Here's what I am qualified to do, though: yank the relays and never put them in again. There, problem solved. If I ever have an extra $800 laying around that I simply can't think way to use then I might take the truck in. Otherwise, I am done.

My father-in-law, the king of the automotive jury-riggers, will be so proud!