Saturday, January 31, 2009

Electrical Madness, The End!

I borrowed a voltmeter capable of handling up to 10A from a friend and did a little more investigating with still confusing results.

I also borrowed a trickle-charger from another friend and started recharging the battery. I figured maybe with a charged battery most of the car would be working and I could get a better idea of what wasn't. After a good six hours of charging, I turned the key, and everything works fine!

The engine started, the dash and radio work, the wipers and headlights work, even the power side mirrors and locks. No problems anywhere. Unbelievable.

What a crazy adventure! It hit some pretty low points:
- I thought I had killed my battery, and would have to buy a new one. ($80)
- The electrical system seemed hopelessly messed up. I was worried the "Body Control Module", basically the CPU for a lot of the cars electrical functions, was busted. ($200)

But in the end, I didn't have to spend a dollar to get the car running, and I learned some great lessons along the way.
- I learned about the car's electrical system and its fuses and relays.
- I learned how to diagnose a battery drain.
- I got some good practice with a voltmeter. It's pretty easy for the probe tips to make a poor connection, resulting in bad readings, so always measure more than once!
- I learned to always disconnect the battery when doing electrical work.
- I learned to always recharge the battery (if it's dead) before trying to diagnose an electrical problem.

So what went so wrong, and why did the electrical system seem so screwed up? I'm still not sure. The car hadn't been driven in at least a month when I did the work, so maybe the battery was low and got further drained as I ran the window motor up and down. I'm thinking that when the battery got too low, the electrical systems got confused, and perhaps some relays became stuck open, causing the battery drain. Maybe the voltage was even too low for the relays to properly close.

At any rate, the Trans Am's back up and running! I'm hoping to get a post up of the car soon, maybe a little clip of the exhaust to start with :).


  1. Not yet... :)

    It's in the 'down' position, though, so with some wax and tire shine the car's ready for cruisin' :)

  2. Be an electrical engineer! Give the average Joe (me) the run-down on why there's a proper process and order of connection when you give someone a jump!