frying out the voltage regulator

[bruceahlgren]

I was coming home from church my radio fizzled out nothing but static then my tachometer quit working then the motor died I charged the battery and found the alternator wasn't charging I bought a new alternator and 175 amp fuse installed them and still getting no charge from alternator took the new alternator back and had it tested it was bad warranty replaced it i had them test it before i left it was good put the second alternator in and it's still not charging took it and tested it it's bad what would be making the new alternator fry the voltage regulated as soon as I connect the battery cables

 

[2000StreetRod]

Mega fuse blown?

. . . I bought a new alternator and 175 amp fuse installed them . . .

Was the 175 amp Mega fuse actually blown? Sometimes the rectifiers in the alternator fail in a shorted mode to ground. When that happens the Mega fuse will blow preventing the battery from being shorted to ground.

. . . what would be making the new alternator fry the voltage regulated as soon as I connect the battery cables?

How did you determine that the voltage regulator was fried? Did the voltage regulator fail on the old alternator and both new ones?

 

[BrooklynBay]

Welcome to this forum! Did the auto parts store have a machine test the regulator to determine that it was internally shorted?

 

[SoNic67]

what would be making the new alternator fry the voltage regulated as soon as I connect the battery cables

1. Some punctuation marks would help in reading your message. I barely make it trough it and almost didn't answer because of that.
2. If you would read the instructions that came with the new alternator, they say never try to use it on a completely dead battery. No alternator can handle that. You need to charge the battery with a charger before starting the truck.
3. I have a feeling that the battery needs to be replaced too - that's probably what fried the first alternator in the beginning. Just adding new alternators on that battery will lead to same results.

 

[itzbinnice]

2. If you would read the instructions that came with the new alternator, they say never try to use it on a completely dead battery. No alternator can handle that. You need to charge the battery with a charger before starting the truck.
3. I have a feeling that the battery needs to be replaced too - that's probably what fried the first alternator in the beginning. Just adding new alternators on that battery will lead to same results.

Thanks for posting that, I was unaware a completely dead battery would damage an alternator. You just taught an old dog a new trick.

 

[SoNic67]

There is no current-limiting build into the alternators. They will try to maintain 14V no matter what - and a dead battery can draw even 100A easily.

 

[bruceahlgren]

1. Some punctuation marks would help in reading your message. I barely make it trough it and almost didn't answer because of that.
2. If you would read the instructions that came with the new alternator, they say never try to use it on a completely dead battery. No alternator can handle that. You need to charge the battery with a charger before starting the truck.
3. I have a feeling that the battery needs to be replaced too - that's probably what fried the first alternator in the beginning. Just adding new alternators on that battery will lead to same results.

I'm using two batteries and both are good. I've replaced the 175 amp fuse and the wire that leads to it from alternator. The newest alternator is not charging still. The alternators failed diode and voltage regulator test and I had the last one checked before I installed it and it passed

 

[bruceahlgren]

Was the 175 amp Mega fuse actually blown? Sometimes the rectifiers in the alternator fail in a shorted mode to ground. When that happens the Mega fuse will blow preventing the battery from being shorted to ground.



How did you determine that the voltage regulator was fried? Did the voltage regulator fail on the old alternator and both new ones?

Yes all of the alternators failed the voltage regulator tests at the auto parts store. I replaced the 175 amp fuse and the wire from the alternator to the fuse and had the last alternator tested before I installed it and now it is bad also. And it has to be doing it either as soon as I connect the cables or as soon as I start the car

 

[bruceahlgren]

Welcome to this forum! Did the auto parts store have a machine test the regulator to determine that it was internally shorted?

Yes it tested the diodes voltage regulator and a third one can't remember what that one was. I had the last one tested before I installed it and it was good. I replaced the wire from the alternator to the 175 amp fuse and the fuse and it still did the same

 

[bruceahlgren]

Was the 175 amp Mega fuse actually blown? Sometimes the rectifiers in the alternator fail in a shorted mode to ground. When that happens the Mega fuse will blow preventing the battery from being shorted to ground.



How did you determine that the voltage regulator was fried? Did the voltage regulator fail on the old alternator and both new ones?

I don't think the Mega fuse was blown but I replaced it anyway. I had the alternators checked and they failed the voltage regulator test. I had the last one tested before I installed it it passed now it's bad also. I also replaced the wire from the alternator to the fuse before I installed the last one

 

[02~Explorer~4.6]

I have a 2002 Explorer 4.6 eng, and am also having an alternator problem. I took the alternator in to the auto elec. shop, and they checked it to find out it was the voltage regulator that was bad. They replaced it and checked it to be working after the new voltage regulator was installed on the alternator. I took it home, put it on the explorer, but still not charging. I called and spoke with the technician that worked on the alternator. He walked me thru some tests with a multi-meter. He had me to check the plug going into the alternator. Mine has two wires going to it. I believe it was with the ignition key on, one side had 12+ volts, but the other one had no volts. He said I needed to have at least half of the 12 volts in that wire. He said I should start checking fuse`s Also, my 4x4 high light is not coming on again after engine starts. I found in checking fuses that #15 fuse on the inside of truck fuse box had no power. The fuse was good but there is no power in this spot to the fuse. (this controls the 4x4, memory seat disable). I cannot find a mega 175 amp. fuse that I am seeing that you have replaced. I have followed the wire harness from alternator back toward the battery, but see no place of a fuse. I will be taking the explorer back to the shop tomorrow, Mon.2/9/2015. Will post what they find.

 

[bruceahlgren]

I have a 2002 Explorer 4.6 eng, and am also having an alternator problem. I took the alternator in to the auto elec. shop, and they checked it to find out it was the voltage regulator that was bad. They replaced it and checked it to be working after the new voltage regulator was installed on the alternator. I took it home, put it on the explorer, but still not charging. I called and spoke with the technician that worked on the alternator. He walked me thru some tests with a multi-meter. He had me to check the plug going into the alternator. Mine has two wires going to it. I believe it was with the ignition key on, one side had 12+ volts, but the other one had no volts. He said I needed to have at least half of the 12 volts in that wire. He said I should start checking fuse`s Also, my 4x4 high light is not coming on again after engine starts. I found in checking fuses that #15 fuse on the inside of truck fuse box had no power. The fuse was good but there is no power in this spot to the fuse. (this controls the 4x4, memory seat disable). I cannot find a mega 175 amp. fuse that I am seeing that you have replaced. I have followed the wire harness from alternator back toward the battery, but see no place of a fuse. I will be taking the explorer back to the shop tomorrow, Mon.2/9/2015. Will post what they find.

Thank you for the info you shared with me. First The 175 amp fuse is just to the side of the fuse box inside the engine compartment. I tested voltage at all my fuses and they all have voltage. But my dash light that looks like a battery does not light up so I traded it with my airbag dash light and it light up the airbag symbol so my bulb is good I called the Ford service Mgr at Southwest ford and after talking with him he had only one idea. He could only think that the computer was sending negative voltage to the voltage regulator through the small green wire with red stripe. I have put 4 alternators on and it fried the voltage regulator immediately on all 4 of them.I've never heard of negative voltage before. But apparently I need a new computer for my explorer. Please let me know what you find out about yours so I can try every possible test before I spend money on a new computer
Thank you.
Bruce ahlgren

 

[2000StreetRod]

Ridiculous!

. . . But my dash light that looks like a battery does not light up so I traded it with my airbag dash light and it light up the airbag symbol so my bulb is good I called the Ford service Mgr at Southwest ford and after talking with him he had only one idea. He could only think that the computer was sending negative voltage to the voltage regulator through the small green wire with red stripe. I have put 4 alternators on and it fried the voltage regulator immediately on all 4 of them.I've never heard of negative voltage before. But apparently I need a new computer for my explorer. . .

In my opinion that diagnosis is ridiculous. I suggest finding a competent repair shop.

On a 2000 Explorer the PCM only uses and monitors the supply voltage. The PCM has no capability to alter the voltage in any way. The LG/RD wire is connected between the voltage regulator and the charge indicator in the instrument cluster. If the wire is not connected then the alternator will not charge the battery. Having started and run my engine with no instrument cluster I know this from first hand experience. However, my alternator (240 amp) regulator did not burn out. Even if the charge indicator lamp is burned out the alternator will still charge if the wire is connected because there is a 470 ohm resistor in parallel with the lamp.

The voltage regulator is integrated with the alternator. Which engine do you have? The V8 does not have the jumper (WHT/BLK wire) between the regulator stator (S) terminal and the alternator stator (S) terminal. Also, I doubt that the V8 and V6 alternators are interchangeable.

 

[SoNic67]

I have a 2002 Explorer 4.6 eng, and am also having an alternator problem.

2002 Explorer is very different from our Explorers, it's a different generation. Your alternator is connected to the PCM (to lower the charging voltage at times and save some insignificant amount of gas). Our alternators are not connected to PCM.

 

[bruceahlgren]

In my opinion that diagnosis is ridiculous. I suggest finding a competent repair shop.

On a 2000 Explorer the PCM only uses and monitors the supply voltage. The PCM has no capability to alter the voltage in any way. The LG/RD wire is connected between the voltage regulator and the charge indicator in the instrument cluster. If the wire is not connected then the alternator will not charge the battery. Having started and run my engine with no instrument cluster I know this from first hand experience. However, my alternator (240 amp) regulator did not burn out. Even if the charge indicator lamp is burned out the alternator will still charge if the wire is connected because there is a 470 ohm resistor in parallel with the lamp.
View attachment 82623
The voltage regulator is integrated with the alternator. Which engine do you have? The V8 does not have the jumper (WHT/BLK wire) between the regulator stator (S) terminal and the alternator stator (S) terminal. Also, I doubt that the V8 and V6 alternators are interchangeable.

I have a 4.0 Ltr sohc V6. My alternator is 130 amp. The first 3 were rebuilt the last one was new each time the voltage regulator was no good immediately after starting engine. The place I called was a Ford dealership and i talked with the service manager

 

[2000StreetRod]

warranty vehicles

I have a 4.0 Ltr sohc V6. My alternator is 130 amp. The first 3 were rebuilt the last one was new each time the voltage regulator was no good immediately after starting engine. The place I called was a Ford dealership and i talked with the service manager

My 2000 stock alternator was also a 130 amp unit. I replaced it with a custom built alternator by a local shop that services emergency vehicle starters and alternators. Most discount auto shops and even dealers rarely have the capability to significantly load an alternator when testing it.

As you can see from the wiring diagram the charging circuit is fairly simple. You must have something unusual going on. Is your engine electrical system stock? Or do you have dual batteries or a high power light or audio system? Have you checked all of the electrical connections? Is the serpentine belt routed correctly?

Unfortunately, most dealers primarily service vehicles under warranty. It's not unusual for them to have little or no first hand experience on a 15 year old vehicle.

 

[2000StreetRod]

I-S-A vs I-D-A regulators

Below is a photo of my stock alternator/regulator.

It looks like there are only two wires that connect to the voltage regulator (green arrow). I seem to recall that the S jumper is internal on some alternators. Also, there are two different types of voltage regulators: I-S-A and I-D-A. Do the alternators you've tried have I-S-A voltage regulators?

 

[bruceahlgren]

My 2000 stock alternator was also a 130 amp unit. I replaced it with a custom built alternator by a local shop that services emergency vehicle starters and alternators. Most discount auto shops and even dealers rarely have the capability to significantly load an alternator when testing it.

As you can see from the wiring diagram the charging circuit is fairly simple. You must have something unusual going on. Is your engine electrical system stock? Or do you have dual batteries or a high power light or audio system? Have you checked all of the electrical connections? Is the serpentine belt routed correctly?

Unfortunately, most dealers primarily service vehicles under warranty. It's not unusual for them to have little or no first hand experience on a 15 year old vehicle.

I have checked voltage at both ends of all the wires. I replaced the black wire with orange stripe and the Mega fuse I have battery voltage at the yellow wire with white stripe and I have very little if any voltage to the green wire with red stripe I have voltage at the 30 amp fuse in the engine compartment. And I'm not sure exactly which 7.5 ampfuse in drivers side dash is the correct one. But I've looked at fuse box schematics and find different things for the same fuse number. For example fuse 15 in one diagram says 4×4 and another diagram says it's for charging system. But I have voltage at all the different ones that said for charging. I'm baffeled I gave never experienced this before where everything checked out ok or close to specs. Just can't find what would be frying the regulator as soon as engine starts

 

[bruceahlgren]

Below is a photo of my stock alternator/regulator.
View attachment 82625
It looks like there are only two wires that connect to the voltage regulator (green arrow). I seem to recall that the S jumper is internal on some alternators. Also, there are two different types of voltage regulators: I-S-A and I-D-A. Do the alternators you've tried have I-S-A voltage regulators?

I do not know the answer to this question. How would I find out this information? And would the wrong one make the regulator go bad like I'm experiencing?

 

[BrooklynBay]

The letters are usually marked on the regulator.