I am apologizing for the really long post now.

Over the past few weeks between work and school I have been wiring in headlight/fuel pump relays, a MSD 6AL, and chasing some gremlins in my electrical system. The gremlins were throwing 18 volts out of the alternator at one point. I discovered quite a few interesting things along the way. I will post some of the harder ones in hopes that it will help others.

1. Alternator over charging:
A few years ago I installed a "high quality" solid state voltage regulator in my truck. Since then I have been doing a lot of repairs and cleaning of the frame or cab floors. No, the battery negative and positives were disconnected. I know what some of you are thinking.

Since most of the repairs are done, I decided to jump into my LED alternator warning light issue. It wouldn't turn off. As it turns out the LED was not allowing the correct voltage to go to the "F" so it would not put out the proper 13 volts needed to turn the warning light negative off. Here is the theory behind it. The warning light uses the alternators "F" as a ground and sends battery voltage to activate the field after the engine starts. Once pushing power, the alternator voltage causes both wires in the light to become positive, eliminates the ground, and the light goes out.

I looked at several sites with the Ford 1G large case alternator and discovered that you can put a bypass around the light. It is listed as 560 ohms. I added the resistor to the dash panel and started the truck to see if the light would go out.

The light turned off and the truck sounded great. I turned on the headlights since it was dark and they were as bright as HID's. A quick check of the volt meter showed 15 volts and climbing. The truck was shut off and I started doubting myself. Double checked all my wiring in the dash and didn't find anything. Took out the alternator/battery and had then checked at the parts store. The battery was fine but the alternator was not pushing anything. The alternator was swapped through a warranty exchange and put it all back in. Started the truck and it is 18 volts now.

The voltage regulator was pulled out and swapped for another one from a friend. Voltage dropped to 11.6 volts when I started it this time but there is not warning light now. In a daze from being defeated, I took the "high quality" and pried the RTV'd cover off and looked inside it. There before me sat a circuit board with the current regulating chip touching both the "F" and "S" after it had melted the solder and slid to make contact.

So what happened you ask? I have a theory that the battery cables came in contact with the body thus frying the VR when I was welding. Although I can't prove it, it is the only thing that makes sense.

2. Light bypass
560 Ohms is NOT the correct resistance for every electrical system. I don't care how many of you claim it is, it's not. After the 18 volts surged through the electrical system the LED died in a blaze of glory. I had to replace it and thought to add a 12V Zenner diode to prevent it from happening again. With the resistor still in place, I started the truck again. It was still not charging. A little upset over it, I cut the resistor out and hard wired the bypass and restarted it. "Holy Mother of God! 13.9 volts and the light is out!" Turned off the engine and switched the key to on; the light was gone again.

Frustrated I walked away. I talked to a engineer friend and he asked me a million questions about it. Then he looked at me and asked where I got my information from. Of coarse he laughs, right? Then he has me go look up Ohms Law and explains the diode I used was rated to 12V and anything over will kill it. As a result I discovered an Ohms Law calculator which asks for two fields to be filled in, volts and watts. Fill it in and learn that I should be using a 47 ohm resistor.

I picked up a resistor package with the correct rating, yet another LED, and a 400v diode. Yes, I know it is a little overkill but I didn't want to change the LED again. Today I wired it all together in the dash and started the truck. 13.9 volts at idle, light works and I am happy. The stupid things you have to go through sometimes to finally get it right. Thankfully my battery hasn't died yet, did I mention it is the same battery from 2001?

If anyone is interested I can post the specific part numbers I used in my adventure.