Ive swapped in a few new alternators this past week on my 5.0L 89 Bronco. Each time I get a overvoltage problem where it puts out 15-16+ volts! Ive replaced the main connector but not the voltage regulator connector. Could a wiring problem explain the overvoltage condition? Im also having a hard time finding new voltage reg pigtail connectors, so any pointers there are welcome.

BTW, reason old alt was replaced was the voltage reg fried and smoked, hence my concern with the connector/wiring even though it apprears OK.

Cheers and TIA,

Starkbier

 

this may sound stupid but if your battery is low or has a dead cell the alternater will put out this much voltage. the normal is 13.8 volts comming out of the alternater.when you check output voltage you do have the battery in the loop dont you? if not it will put the alt into full output and you would see this kind of voltage.

 

the battery is in the loop and I put it on a 2amp trickle charge overnight before putting in the new Alt. It was well above 12V after the trickle charge.

Maybe its just not the right alt for the Truck...parts store had a hard time matching it....

SB

 

is the pulley on the alt the right diamater or is it a little bigger. bigger will spin it faster but the regulator should keep the voltage down to where it should be.

 

Are you useing new alts, or used? I had the same problem, swapped in a coupla used same thing, even puta new regulator on the last one, same thing. We were all thinking the fires, there has been problems in the wire harness from the alt to the solenoid, where it connects with the battery.

I would have battery check to make sure, a load test will show a problem a volt gauge wont, ie 13 volts till you load then low.

A bigger pulley will mak eit turn slower, a smaller pulley will make it turn faster, but still the regulator should stop it.

Clean very well all battery cables, and studs, and take all the hot wires off where they meat at the solenoid, and clean all them good.

I would ask them for anouther alternator, next. Most parts stores have a tester, so have them test it all to make sure the battery is good, and the alt is over charging, if it is they should have no probs giving a new one. They can also bench test the one you got now to see what its doing, if it tests good, and a swapp doesnt fix it, continue

Replace the harness, from the alt to the solenoid. If you have a burnt wire like they sometimes do, it will do this. I know our napa carries them, if not go to the junk yard and get one, look for one in the best shape. There was a recall on some models, so you may get one of the new ones, but looking it over good, for any signs of being hot and stiff. The odds are in your favor that even a used one is better then yours if yours is bad.

On mine, a fourth alt swap fixed it.

If t

 

Ive had three new alts and all have been in overcharge mode. Last nite I swapped a good battery in and same results. Today I go to NAPA and find the right connector that feeds the voltage reg. Since this is still a stock connector, and they are known to have problems in the past I have to think the alt is not getting the right feedback signal from the battery circuit to know to regulate the voltage.

SB