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Old 03-15-2017, 11:32 PM   #1
RED72blazer
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buzzing external voltage regulator 72 K5 blazer

Alright, in my 1972 blazer recently my charging system was overcharging. I traced it to a bad regulator. Replaced it. It charges fine. But there is a loud buzzing coming from my new regulator. Figured it was a bad new part. Replaced it. Still buzzing. Went to another brand. Still buzzing. So now just because. I changed the alternator. Still buzzing. Then I got a 80 dollar ac Delco regulator. Still buzzing. Today I cleaned all the grounds. Still buzzing. Anyone have any ideas on what is going on? This is getting tiresome. I do have a new wiring harness from M&H. I've had zero problems in 10 years or more with the stock system. I do not want to go to a 1 wire alternator or internal regulator. I just want the stock system to work. Any help would be great. Thanks
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Old 03-15-2017, 11:52 PM   #2
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Re: buzzing external voltage regulator 72 K5 blazer

Do you have the regulator grounded to the sheet metal and to the alternator?
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Old 03-15-2017, 11:57 PM   #3
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Re: buzzing external voltage regulator 72 K5 blazer

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Originally Posted by VetteVet View Post
Do you have the regulator grounded to the sheet metal and to the alternator?
The alternator and the regulator both have the "factory" grounds installed. I even ran a temporary wire between the 2. No difference.
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Old 03-16-2017, 12:24 AM   #4
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Re: buzzing external voltage regulator 72 K5 blazer

Are you hearing the buzzing in the regulator or in the cab with the radio on. The condenser on the VR must be hooked up or you will hear the buzzing in the radio.

Here are some threads on the buzzing that might solve your problem.
https://www.google.com/search?domain...D%3A1%3B&hl=en
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Old 03-16-2017, 12:30 AM   #5
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Re: buzzing external voltage regulator 72 K5 blazer

No radio installed currently. It's definitely the regulator. You can feel it if you put your hand on it.
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Old 03-16-2017, 12:06 PM   #6
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Re: buzzing external voltage regulator 72 K5 blazer

The buzzing is caused by the points in the regulator opening and closing at a very rapid rate more than normal probably due to the voltage sensing circuit for the alternator. This would be the blue wire to the alternator and the red wire from the regulator to the soldered junction. Or you may have just gotten another bad regulator.

Silly question: did you re-install the regulator using the little rubber washers? I know, but I have to ask.

A very good option would be the solid state regulator made by Wells which is sold at Napa and Autozone PN. VR 715 for pre 73 GM vehicles. Here is a good thread on another forum about it.

http://www.chevelles.com/forums/45-c...-60s-cars.html
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Old 03-16-2017, 05:40 PM   #7
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Re: buzzing external voltage regulator 72 K5 blazer

............

http://www.autozone.com/batteries-st...e&newYmme=true
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Old 04-05-2017, 05:48 PM   #8
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Re: buzzing external voltage regulator 72 K5 blazer

Okay. Maybe I wasn't clear. I understand how the voltage regulator works and what is making the noise. The fact is, it's shouldn't be making that noise and if I let it go, it burns up the regulator. I do not think that switching to another style regulator will help. It will burn up too.

What I am wondering is what is causing all this to happen. Obviously something is wrong. Honestly I could live with the buzzing. But I need it to stop burning up regulators.
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Old 04-08-2017, 01:33 PM   #9
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Re: buzzing external voltage regulator 72 K5 blazer

Sorry I missed your repost. I covered most of the common reasons for the buzzing. It appears that your alternator and regulator are OK and the wiring harness is fairly new.
This leaves a wiring issue or a possible short to ground in the charging circuit that is not fused.This short may be throwing the alternator into a full charge output mode and if the short is intermittent it will cause the alternator to cycle between normal and full charge.

Another possibility is that the blue and white wires from the regulator are not making a good connection on the alternator end or the regulator end. I would do a continuity check on those wires and also check for a full 12 volts on the red wire at the regulator plug. This is the sensor wire which tells the regulator what the system voltage is and lets it adjust the alternator output to compensate.

Check the voltage of the brown wire with the key on and with it off. 12 volts on and zero with it off.
Do you get a charging light or a flickering needle on the ammeter if you have a gauge dash?
A bad diode in the alternator could cause the regulator to buzz, If you disconnect the alternator plug does the buzzing quit? A shorted diode would be the short to ground I mentioned above.
A wells vr 715 is totally different to the points style and it is around $20 bucks. If everything checks out. It might be a solution.
Other part numbers for the solid state regulator are AC Delco # D663
and GM # 1119519. The sold state regulators shunt the excess voltage from the alternator to ground much like a Zener diode.

I know you want to stay with the OEM stuff but you wold be much happier with an internally regulated alternator.

Mid eighties 12 SI is the ticket.


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conversion wiring is very easy.


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Or you can even go to the newer CS style.


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the conversion is just as easy but you need to wire in a 75 to 300 ohm resistor.


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The brown wire goes to the L terminal and the red wire goes to the S terminal.
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Old 08-28-2021, 03:05 AM   #10
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Re: buzzing external voltage regulator 72 K5 blazer

Reviving an old thread here. I'm having the same issue as the original post...and going crazy trying to chase this down.

I'm on my 2nd external VR and both have the same buzzing (ie not a bad part).

Reading through VetteVet recommendations.
- I confirmed 12V on red.
- Blue and White continuity test passed.
- On Brown I'm getting 3V with key on (vs 12V as stated above) and 0V with key off (0V above). Any ideas to why I'm getting 3V instead of 12V?

RED72blazer - How did you solve this? Anything you can share?

Thanks!!
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Old 08-28-2021, 12:43 PM   #11
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Re: buzzing external voltage regulator 72 K5 blazer

The brown wire comes from the key switch and runs through a 10 ohm light (resistance) on the light dashes and also through a resistance wire on the gauge dashes. This resistance wire is there to protect the charging circuit to the VR in case the light goes out (blows).
I would run a jumper from a 12 volt hot source in series with a 10 ohm resistance to the brown wire connection on the VR and see if the buzzing stops. I have an external wire like this on my truck and it works fine. Temporary for testing of course for an SI alternator.
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Old 08-28-2021, 04:19 PM   #12
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Thanks for the response!

This is interesting. I recently put in a Dakota gauge cluster. After install I noticed that my steering column (Park Neutral Drive Reverse Etc) does not light up anymore. It’s noticeable at night when it’s dark cause it’s hard to tell how the transmission is engaged on the column. Sounds like maybe I messed up that resistance wire/light and it’s having a downstream impact.

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The brown wire comes from the key switch and runs through a 10 ohm light (resistance) on the light dashes and also through a resistance wire on the gauge dashes. This resistance wire is there to protect the charging circuit to the VR in case the light goes out (blows).
I would run a jumper from a 12 volt hot source in series with a 10 ohm resistance to the brown wire connection on the VR and see if the buzzing stops. I have an external wire like this on my truck and it works fine. Temporary for testing of course for an SI alternator.
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Old 08-28-2021, 06:25 PM   #13
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Re: buzzing external voltage regulator 72 K5 blazer

The resistor wire is not related to the steering column shifter lighting. What lights the steering column shifter is a fiber optic cable that collects light from one of the instrument cluster illumination bulbs. Here is a picture of what it looks like, from a post by LockDoc



I don't know about aftermarket instrument clusters or how they are illuminated. If it uses a 194 bulb in a twist lock socket, then all you would have to do is use the original style bulb holder and connect it to the fiber optic cable that is probably hanging loose under your dash. As an alternative you could probably connect a light bulb and get it glowing in the original bulb holder and run the fiber optic cable to it, and put the assembly in a small metal project box or metal bandaid box somewhere under the dash.
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Old 08-28-2021, 10:47 PM   #14
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Re: buzzing external voltage regulator 72 K5 blazer

I think I read where they discontinued the fiber optic cable in the later years and went to the regular bulb type. If he has the socket then he can just install a 194 bulb and wire it to the fuse panel Pnl Lts fuse. The Dakota cluster probably isn't compatible with the old style wiring.
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Old 08-31-2021, 02:55 AM   #15
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This is probably dumb but I am no good at electrical and it makes me nervous. Just to be sure I get this right…

Your recommendation is to tap one end of the jumper into the brown wire at the VR. Add a 10 ohm resistor on the jumper. And tap the other end of the jumper into a 12V hot source. The hot source is constant 12v or key on (acc) hot?

Hopefully that Q makes sense.

Thanks for all the help.

Quote:
Originally Posted by VetteVet View Post
The brown wire comes from the key switch and runs through a 10 ohm light (resistance) on the light dashes and also through a resistance wire on the gauge dashes. This resistance wire is there to protect the charging circuit to the VR in case the light goes out (blows).
I would run a jumper from a 12 volt hot source in series with a 10 ohm resistance to the brown wire connection on the VR and see if the buzzing stops. I have an external wire like this on my truck and it works fine. Temporary for testing of course for an SI alternator.
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Old 09-02-2021, 02:13 AM   #16
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Re: buzzing external voltage regulator 72 K5 blazer

Quote:
Originally Posted by Dan_P View Post
This is probably dumb but I am no good at electrical and it makes me nervous. Just to be sure I get this right…

Your recommendation is to tap one end of the jumper into the brown wire at the VR. Add a 10 ohm resistor on the jumper. And tap the other end of the jumper into a 12V hot source. The hot source is constant 12v or key on (acc) hot?

Hopefully that Q makes sense.

Thanks for all the help.


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You can use a 12 volt constant hot source as a temporary jumper, just remember to disconnect it after the test or it will drain the battery.

You might have a poor connection on the brown wire in the firewall plug or at the key switch which could reduce the voltage at the VR to 3 volts.

This diagram shows the ACC wire and the 24 ga. resistance wire on the key switch. The 12ga brown wire runs to the fuse panel and the resistance wire runs to the inside connector for the firewall block.

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Here's the engine side of the firewall block. there are more than 1 brown wires in it so you'll need to find the 16 gauge wire for the VR.


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