Anyone Replace Voltage Regulator in Alternator?

[Bandit Runner]

So I’m pretty sure my voltage regulator isn’t working properly in my alternator. I bought a 200amp alt from @Bumper2BumperAuto about 2 years ago. It was working great up until a month ago. My battery dash light started flashing on and off. Also, my voltage (as read on my ScanGuage) was reading low at like around 11.5volts, but was also jumping around a lot anywhere from 10-15volts. I was pretty sure it wasn’t a battery problem, so I replaced the alt with my original OEM alt that luckily I kept. All my voltage problems immediately went away, and no more battery dash light. So it is definitely something with the high amp alternator.

After reading several alternator threads on here, it looks like it is probably the internal voltage regulator. I don’t think it is worn brushes, because I only have around 15K miles on this alternator. This high amp alt is supposed to be a rewound OEM unit.

Interestingly, I took the alternator to AutoZone and had it tested. They said it passed their tests for what it is worth. I talked to the guy there about my issue, and he also mentioned a possible bad regulator.

I did read a few instances where guys had a valve cover gasket leak, and thought that oil had dripped into their alternator and messed it up. I do have a valve cover gasket leak, but when I removed the bad alt, I didn’t see any oil on it but you never know. Any thoughts on this being the problem?

Has anyone replaced the voltage regulator in their alternator? How difficult would it be? Where would I find a part number for the regulator, and where would I purchase this from? Denso?

I contacted Bumper2BumperAuto and he said they rarely have issues with the high amp alternators that they sell. Unfortunately, I am past the 1-year warranty date. I will also be contacting the manufacturer and see what they have to say about this.

Any input would be greatly appreciated. Thanks.

 

[JRZEE2000TR4LTD]

So I’m pretty sure my voltage regulator isn’t working properly in my alternator. I bought a 200amp alt from @Bumper2BumperAuto about 2 years ago. It was working great up until a month ago. My battery dash light started flashing on and off. Also, my voltage (as read on my ScanGuage) was reading low at like around 11.5volts, but was also jumping around a lot anywhere from 10-15volts. I was pretty sure it wasn’t a battery problem, so I replaced the alt with my original OEM alt that luckily I kept. All my voltage problems immediately went away, and no more battery dash light. So it is definitely something with the high amp alternator.

After reading several alternator threads on here, it looks like it is probably the internal voltage regulator. I don’t think it is worn brushes, because I only have around 15K miles on this alternator. This high amp alt is supposed to be a rewound OEM unit.

Interestingly, I took the alternator to AutoZone and had it tested. They said it passed their tests for what it is worth. I talked to the guy there about my issue, and he also mentioned a possible bad regulator.

I did read a few instances where guys had a valve cover gasket leak, and thought that oil had dripped into their alternator and messed it up. I do have a valve cover gasket leak, but when I removed the bad alt, I didn’t see any oil on it but you never know. Any thoughts on this being the problem?

Has anyone replaced the voltage regulator in their alternator? How difficult would it be? Where would I find a part number for the regulator, and where would I purchase this from? Denso?

I contacted Bumper2BumperAuto and he said they rarely have issues with the high amp alternators that they sell. Unfortunately, I am past the 1-year warranty date. I will also be contacting the manufacturer and see what they have to say about this.

Any input would be greatly appreciated. Thanks.

I would think you may need the voltage regulator that goes to THAT 200A alternator.

 

[LittleCaesar]

That sounds like it. Why did you replace your original one in the first place? How much will it cost just for a new regulator from the company?

I'd just replace the brushes in the OEM one and keep driving....

 

[MN4runnerman]

Maybe see if you can find a local rebuilder. I had to do that to get a starter rebuilt for my neighbors 1948 ford tractor. I could find the parts but I had no clue what to get so I brought it to a company and they did it for ~$60.

 

[HiLife]

I would get the alternator tested by a auto electronics builder as the business would have more specialized tools to properly tackle troubleshooting. I forgot if the rectifier is built in along with the regulator but, the rectifier is also worth troubleshooting. There should be 3 diodes that make up the rectifier. Those are easily check with a mulimeter. If you can change the brushes you also have the knowledge of swamping out the regulator and rectifier.

 

[Bandit Runner]

Thanks for all the responses. I just sent the manufacturer an email, so we'll see what they have to say.

I would think you may need the voltage regulator that goes to THAT 200A alternator.

Do you think the regulator would be different between the OEM and high amp alternators? I assumed they would be the same.

That sounds like it. Why did you replace your original one in the first place? How much will it cost just for a new regulator from the company?

I'd just replace the brushes in the OEM one and keep driving....

I wanted a high amp alternator because I run a winch, ARB twin air compressor, 2000 watt inverter, and way too many lights! I thought it would be an improvement over the OEM unit.

Maybe see if you can find a local rebuilder. I had to do that to get a starter rebuilt for my neighbors 1948 ford tractor. I could find the parts but I had no clue what to get so I brought it to a company and they did it for ~$60.

I would get the alternator tested by a auto electronics builder as the business would have more specialized tools to properly tackle troubleshooting. I forgot if the rectifier is built in along with the regulator but, the rectifier is also worth troubleshooting. There should be 3 diodes that make up the rectifier. Those are easily check with a mulimeter. If you can change the brushes you also have the knowledge of swamping out the regulator and rectifier.

I'm looking into this, but so far haven't found a reputable local place that specializes in rebuilding alternators. I'll keep looking.

 

[JRZEE2000TR4LTD]

Do you think the regulator would be different between the OEM and high amp alternators? I assumed they would be the same.

No, the higher amperage would require a different regulator. The stock alternators came in 70A and 80A varieties, which have 2 different regulators.

 

[HiluxSurf SSR-G]

OP, are you referring to the IC regulator (Toyota calls it the Generator Regulator assy)? If yes, it is located behind the rear cover of the alternator via 2 screws. It's the one with a heat sink. The part number is 27700-50030. It is the same for the VZN185 70A and the 80A alts. But I don't know if it's the same one used for aftermarket alts, although the socket should be the same.

 

[JRZEE2000TR4LTD]

OP, are you referring to the IC regulator (Toyota calls it the Generator Regulator assy)? If yes, it is located behind the rear cover of the alternator via 2 screws. It's the one with a heat sink. The part number is 27700-50030. It is the same for the VZN185 70A and the 80A alts. But I don't know if it's the same one used for aftermarket alts, although the socket should be the same.

Is it the same? It has to be different if the load is different. This shows 2 different part #s for the 70 and 80 amp alternators, although I guess you could use an 80A regulator in place of an 70A alternator.

https://www.toyotapartsdeal.com/oem/toyota~regulator~assy~generator~27700-50030.html

https://www.toyotapartsdeal.com/oem/toyota~regulator~assy~generator~27700-75020.html

Here's the entire page.

https://www.toyotapartsdeal.com/parts-list/2000-toyota-4runner/alternator.html

As I said it has to be different if the current is greater. This, by the way, only pertains to the OEM alternator, and really doesn't help the OP as he has an aftermarket alternator.

 

[HiluxSurf SSR-G]

You are also correct, thank you. Just to clarify, I have compared the IC Regulators for the 5VZ-FE from late 1997 - late 1998 (70A) vs that from late 1998 - 2002 (80A) These two alternators use the same IC Regulator (27700-50030). However, for the early 1996 - late 1997, a different alternator but also 70A, the IC Regulator used was different.

https://www.toyotapartsdeal.com/par...150,27060-75170,27060-62190-84,27060-75150-84

Is it the same? It has to be different if the load is different. This shows 2 different part #s for the 70 and 80 amp alternators, although I guess you could use an 80A regulator in place of an 70A alternator.

https://www.toyotapartsdeal.com/oem/toyota~regulator~assy~generator~27700-50030.html

https://www.toyotapartsdeal.com/oem/toyota~regulator~assy~generator~27700-75020.html

Here's the entire page.

https://www.toyotapartsdeal.com/parts-list/2000-toyota-4runner/alternator.html

As I said it has to be different if the current is greater. This, by the way, only pertains to the OEM alternator, and really doesn't help the OP as he has an aftermarket alternator.

 

[nc-grayson]

i guess its prudent to tag along on this thread rather than starting a new one. I'm kind of in the same boat as [MENTION=55891]Bandit Runner[/MENTION]. My oem denso puts out 14+ volts while driving, but 50% of the time when I get to a stop light, it drops down into the mid-to-low 12s. shift to neutral at the light, back up to 14+. give it gas when the light goes green, back up to 14+.

Is this a voltage regulator issue, or brushes? I've also seen mention it may be IAC related?

TIA

 

[19963.4lsr5]

Usually a open diode will be reduced output.

The diode bridge is what handles the current. All the regulator does it control the field current to maintain a predesired output at the sense wire in the bridge. You can't have 80a diodes in a alt capable of putting out 200a. Plus the little frame and no big cooling fan in the alt to handle the more than double the output of the alt is not good even if there is a 200a diode bridge in there......that 200a is not continuous.


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