93 Thunderbird.....voltage problem!! January 08, 2006, 01:11:39 PM I think my thunderbird has a voltage problem. when i am completey stopped and running my headlights, rear defrost and heater fan my voltmeter gauge drops way down past the halfway mark and my headlights dim and also my heater fan slows way down. as soon as i start to speed up..the gauge goes back up to normal, headlights get bright again and heater fan picks back up to proper speed. everythings fine if i'm only running my headlights and heater fan, but as soon as i turn on rear defrost thats when the gauge goes down.i hooked a volt meter up and the lowest it got was around 11.5 volts. when i had the heater, rear defrost and headlights on it was a little over 12 volts, but when i put the car in drive it dropped to about 11.5 volts.i posted that a few days ago on another forum and they are stumped, maybe you guys can help me. i just installed a new alt today and its still doing the same thing. the battery is only like 6 months old. thanks Quote Selected
93 Thunderbird.....voltage problem!! Reply #1 – January 08, 2006, 02:00:25 PM sounds like your alt is going. having a problem with dead batteries? Quote Selected
93 Thunderbird.....voltage problem!! Reply #2 – January 08, 2006, 02:39:11 PM Check yer belt and tensioner. If the belt is slipping the alt won't charge at idle but will pick up at higher RPM's. A slipping belt won't always make noise, so just 'cuz it ain't squealing doesn't mean it ain't loose. With the engine off try turning the alt by manually turning the alt fan blades. If you can turn the alt without the belt moving the belt is slipping.Also, check your battery. If it is weak the alternator will have a hard time keeping up with the electrical demands. And finally, if everything else checks out OK, try another allternator. I know you just put one on, but the cheap rebuilts are not always good (I went through several on my T-Bird).One more thing: If you have underdrive pulleys this is normal. Even if you don't, if your replacement alt has a slightly larger pulley than youor old one it will be underdriven. If all else fails you could "overdrive" your alt by putting a slightly smaller pulley on it - you don't want to overdrive it too much, though, because it could spin itself apart at high engine RPM Quote Selected
93 Thunderbird.....voltage problem!! Reply #3 – January 08, 2006, 02:40:18 PM i just installed a new alt today, i did have a problem with the car not starting like 6 months ago, but that was when i got a new battery. and i've been having this voltage problem with the old and new battery and alt Quote Selected
93 Thunderbird.....voltage problem!! Reply #4 – January 17, 2006, 12:54:37 PM ok i finally had time to take the picshttp://i51.photobucket.com/albums/f370/Spyderrc10gt2/P1010001.jpgthis first pic is of the car idleing with no acc. onhttp://i51.photobucket.com/albums/f370/Spyderrc10gt2/P1010003.jpgthis second pic is of the car in Drive with no acc. on (tach drops a couple hundred rpms)http://i51.photobucket.com/albums/f370/Spyderrc10gt2/P1010004.jpgthis third pic is with the car in Drive and headlights, heater fan and rear defrost on.i did install a reman alt. and it helped a little, the volt gauge used to drop below the N in normal but now it stays on top of it. is my car not idleing high enough?? could someone with the same car could tell me what theirs idles at??there isn't underdrive pulleys. i tried to turn the alt with the engine off and it didn't budge. and i just took my battery to a local battery shop and had them test it and they said it was fine Quote Selected
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