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Old 09-03-05, 01:39AM   #1
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Join Date: May 2004
Location: Clackamas, Oregon
Posts: 20
Default 68 FB 350 Need Help With Electric Problem

Good evening friends, my name is Mike. I own a couple of 68 Firebirds and one has just started having a problem I can't understand or fine. When I'm driving it at night (just started the last time out) everything works fine. But, when I go to turn on the heater fan, while my head lights are on. The car just dies without any warning. No hesitation, just going along and hit the fan switch and dead. This happens at any speed. Now, sometimes it didn't happen but about 80% of the time it will. However, shut off the lights, and the fan works fine. Battery is pretty new and a high end sealed Delco. Always kept on a battery tended plus when it's sat a long time or will sit. Headlights are normal replacements not halogen. The Alt was bought new about 2000 miles ago and I converted it to a single wire alt. Never had a problem until now.

I will mention one thing though. The door switches I found out oe was bad and it would not shut the lights off. So, I removed the fuse and the switches until I can replace them. Or rather I removed one end os the fuse to the door switches. Otherwise the interior lights would stay on.

I need to know how to check the output of a single Alt, and where else the problem may be? The battery was about $90.00 and a delco that has never given me a problem before.

Any ideas what may be the cause?? Thanks in advance, and good evening friends.

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Old 09-03-05, 01:51AM   #2
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Join Date: May 2003
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Posts: 19,188

Welcome to the board Michael, Hum ? that's a tough one, it sounds
like there's a dead short in the light switch, or it's mess up and shorting
out the ignition. It could also be the atler. it could have a bad diode, when
you turn on the light switch it's so much of a draw it shorts out, I'd take and
have the alter checked first, it should put out 12 volts at 1500 rpms, but
I don't think testing for voltage can tell you if it has a bad Diode.
The things they hide, the way they spin things, the excuses that they make and the things they omit.
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Old 09-03-05, 04:16AM   #3
A. X.
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This may be a problem with your wiring. The problem could be the alt wire that runs to your battery. This wire is what charges your battery and the system. If it's too small, you will not be getting the right amount of current to run all of your accessories and charge your battery. It will play hell on your battery too. This wire is the one that runs from the back of the alternator post to either the starter or straight to the + post of your battery.
A simple way to test this is to take a larger wire than what you have and connect it from the rear post of the alt, straight to the + post on the battery. You can also double up two 10 ga wires if you don't have anything bigger. Then drive around and see if it works. If it does work, you're set. if not, it's something else. You can leave the original wire connected, because the power will take the path of least resistance to the battery.
If this isn't the problem, come back, and we'll work it out. Wiring is a pain, and sometimes you just gotta go through everything to find the problem.
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Old 09-03-05, 10:09AM   #4
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Join Date: May 2004
Location: Clackamas, Oregon
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Aa.X. thanks for the information. Although I bought a wire set made for the application that's not saying it can'e be bad, or not big enough to carry the load. My problem is that I have used it this way for a long time before I had any problems. I will look at it though and try the larger wire idea since I have larger stuff anyway. I'm also able to connect up the door switches again with switches I pulled from the junk yard and cleaned real well. I know they work, so now all I have to do is fish for that white wire that's inside the door again. That's OK though since I love salmon fishing and I'm used to spending hours at a time without catching anything. Good ay friends.

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Old 09-03-05, 05:19PM   #5
A. X.
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We'll just start with common problems and take it from there. Did you add any extra electrical components like electric fans or fuel pump or water pump? If so, they will put a load on your charging system.
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