Join Date: Jan 2009
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Dead Batteries Caused by Bad Voltage Regulator
I just wanted to pass on the experience that I had dead batteries caused by a bad voltage regulator. The symtoms went like this. Truck running perfectly on Saturday after pulling a 10000 lb boat. Truck sits on Sunday. Monday morning when I go to work, after turning the key, all I hear is the chatter of the solenoid. Batteries were very low.
So I take the truck to AutoZone for a diagnosis. Batteries and alternator are good, batteries are just low. So I buy a charger for $53 from AutoZone (every house needs a good battery charger anyway). Next day, when I get ready to go to work, again no crank and I hear the wonderful noise of the chattering solenoid. Get the jumper cables out again and this time I drive to Ford so they can trouble shoot the electrical system.
Two hours later I get a call from Ford and the service scheduler tells me that the mechanic told her that the voltage regulator in the alternator went bad. I thought to myself, that does not sound right because the voltage regulator is on the fender well. I tell her that the voltage regulator is a $16 dollar part, how much would it take for you to fix the truck? She said $360 with labor. I said, hmmm, that sounds kind of expensive and she said well you have to replace the alternator. I said, well, I can buy an alternator for much cheaper than that and replace it myself, how much is the Ford remanufactured and she said $165. She said the charge now is $45 and we are charging up your batteries. I said please give me my truck back and thanks for finding the problem.
When I get to Ford, I ask to speak to the mechanic and we both go back to see the truck. The alternator is unhooked so it does not drain the batteries. He tells me your voltage regulator in the alternator is bad so you will need a new alternator. I told him, the voltage regulator is external from the alternator and here it is on the fenderwell. He then gets an embarrased look on his face and he said, you are right. I told him I am headed to the Zone next for a $16 voltage regulator.
I head home first to verify what this mechanic is telling me because he did not score a lot of points saying the voltage regulator was internal to the alternator. I got my multimeter and measured the voltage of the battery with the alternator clipped on and off and did measure a voltage drop with the alternator clipped. I ran to the zone, bought the voltage regulator, changed it in the parking lot of the zone, and shazam, everything is working a lot better. It has been two days now and no dead batteries!
The old motorcraft voltage regulator was original from 1991 and it did its duty. So moral of the story, if you have that fantom current draw when the truck is parked, replace the voltage regulator after doing a current check on your alternator.
Cost to fix = $53 + 45 + 16 = $114
If I would have read the diesel stop first, I might have saved $98! Good luck and keep that old truck.
1991 F-250, XLT, 7.3 Liter IDI Diesel, 4x4, automatic w/ overdrive, 3.55 rear end, Tow Package/controller, Power windows, AC, Cruise Control, 209K Miles, Miraculously Everything Works! Upgraded from a 1999 Ranger.