Alternators keep going bad

[Gstewart]

Why is this alternator circuit different from all the others and all the diagrams? The regulator does not connect directly to the field connection.

Bought this 1995 Edie Bauer Explorer in May 14. Garaged all it's life. Everything looks like new. It doesn't normally get much use so before a long trip we took it for a 150 mile trip to test it. Twice on the way back the voltage meter dipped down and the battery light came on for about 10 seconds. I replaced the alternator. After turning in the core, the new alternator quit on the way home. Went back and got another one, but let them talk me into buying a battery too. After turning in the core that one quit on the way home too. Took it to local shop and they decided that alternator was bad and took it back to the parts store, where they checked it on their machine and agreed that it was bad. Now it is acting up again. If I take it for a drive the voltage meter is almost sure to dip down and the battery light come on several times during the trip. I have checked the voltages on the alternator and compared them to my identical looking alternator on my 94 Ford Ranger. The voltages are identical on the two outside pins (3pin connector) (12v) and the center pin has 7.48v (while idling). The only difference is that on my Ranger the center pin jumpers right over to the field connection on the alternator, but on my Eddie Bauer Explorer the white and black wire disappears into a bundle and then comes back to the field connection. This "little nuance" does not show up on any wiring diagrams that I have seen. All the diagrams show the jumper directly to the field connection. All the other cables and connections seem good (grounds and hot wires). The only one I can't really check is the black and white wire that should be a jumper but in reality goes into the wire bundle first. For all I know that wire goes through ten things before it comes back to the field connection. One more thing that could be related or not. Sometimes the idle is a little low and pressing the gas pedal results in hesitation. Then during the hesitation moment the meter dips and the battery light comes on, however who could blame an alternator for that. My other problem seems to not be related to the hesitation events.

Anyone have any idea about where that black and white wire could be going when it leaves the regulator on its way to the field connection?

Thanks for your help.

Gstewart

 

[Gstewart]

Found the problem

I am replying to my own post so I can let everyone who read it know what I learned. I finally called an auto-electric shop and they pointed out that I had to at least cut away from my original supplier or I would always be wondering if they were just giving me bad alternators. So I told the store that I wanted to return the alternator (the 4th one) and get a refund, they said ok. I had the auto-electric shop put in one of theirs. When I left there, I didn't get a half mile away and the voltage started to drop. It was after dark so I just hurried home. In the next day or so I convinced myself that it only goes bad when the temperature is below freezing. I also decided to just remove the mystery wire that should jumper from the regulator to the field connection but instead goes off into a wire bundle and then returns to the field connection. I took it off and put in a jumper and the car immediately started working and hasn't stopped no matter what the temperature is. We took it on a 300 mile trip and it worked perfect the whole time. So I don't know where that wire was going or what it was doing but it was the cause of all the problems. Neither does there seem to be any bad affects from not having the original wire hooked up.

The auto-electric guy tells me that what I am calling the field is really the stator, but he doesn't have me convinced. But other than not properly explaining my problem to others I can't see how that affected how I got it fixed.

 

[Gstewart]

Simple fix for my 5 failed alternators

I am again replying to my own post. In the end I went through 5 alternators before my local care repair place fixed it. It turned out it was not the weird wiring that should have been just a jumper from the regulator to the field coil, because a couple of months later it happened again. This time I decided to buy a used alternator from a junk yard. Again it worked for a while. When that one started to fail intermittently again, I went back to the schematics. The one thing I knew was that the 12v that feeds the regulator would go away when it failed. One day my wife noticed that if I was under the hood checking on the problem that the dash voltmeter would jump up and down. So I started to hit things and found that when I hit the power fuse block it would alternately come and go. So, looking at the schematic, I decided the problem was either the regulator fuse or the connector that takes the voltage over to the regulator. I remembered that one time I had fixed it by taking the fuse out and putting it back in. So I checked the fuse again and didn't see a problem. The connector was hard to get to so I took the car to my local shop. I explained how hitting the fuse block made the voltage come and go. And asked them to re-seat the connector that I could not reach a few times. They fixed it in twenty minutes. Turned out it was the contacts in the fuse block. They were able to bend them so the fuse made good contact and now it is permanently fixed. It hasn't failed once in several months and 2,000 miles. I went through five alternators, probably all good. Since Advance Auto took theirs all back and refunded the original purchase price, I was only out for the one from the auto electric shop and the one from the junk yard.

 

[Flash]

Glad it worked out for you.

I had a similar problem with the high speed thermo fan on my BMW, there was just too much current going through the fuse holder and it melted.
Even a heavy duty inline fuse holder wouldn't hold up. Didn't blow the fuse though.