How To Test An External Voltage Regulator (Pre-73 C10)

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How to perform a voltage regulator bypass jumper test on a classic GM car/truck. Is your alternator not charging? Battery voltage low? It may not be your alternator!

[@JamesAutoDude]

THANKS! I confirmed that my alternator was good before blowing money on a new one 😅 Also, for anyone curious.... F goes to F, R goes to #2, red goes to battery & alternator, and brown goes to the light which then the light goes to the ignition switch, but then there's another wire coming off ACC that also goes to brown Thanks again!

[@algo3an]

Finally someone explains it. No one likes to buy a new alternator and finds out the old one has no issue.

[@innando]

I just did and ai am afraid to find out that the at this whole the problem it was the voltage regulator 😅

[@clarka5650]

Y E S. 64 nova with the same setup. Solid state replacement unit I didn’t know how to test but I DO NOW!! Thanks a million

[@myscooter4]

I’ve been racking my brain trying to figure out my voltage drop on my 1963 C10 Chevy. This video helped me tremendously! Thanks!

[@johnhouston6383]

My '72 GMC truck had a voltage regulator issue, when I went to replace it with an old one I had changed out unnecessarily decades ago I found 2 of the blades had enough rust on them to possibly be the problem. I sanded the rust off and put it back together and to my surprise it works just fine again! I can put that old regulator back on the shelf again,who knows,' I might actually need it someday! Thanks for making this video, it was very helpful.

[@sickofliberals9403]

Love these old trucks, I have a 68 Chevy and working on it is so much simpler than my newer dodge

[@danmoore4501]

You my friend just saved me a bunch Of time and money. So thank you

[@Hammer-xo7nj]

Thank you so much. I couldn’t figure out my voltage drop. You did fantastic and this is the exact reason for my problem. Your awesome.

[@DJrainbizzles]

Useful information! Found the issue with my car’s charging thanks to you, thanks a million

[@brianandrews7099]

Just fyi, replacing the internal regulator in a newer types of Delco alternators isn’t too difficult either. I just replaced one for the first time. Took me about 40 minutes to open the case, check/clean everything, grease the front and rear bearings, and replace the regulator. Saved me about $40.00 over just replacing the entire alternator.

[@BASimmons]

Thanks! You jjst helped me fix the regulator on my 1969 Convertible Delta 88!

[@pooorman-diy1104]

you know what ?? ..Over engineered BMW ..Audi ..etc are junk ..compared to this old robust simple car .. Please press 'thumbs up' if you agree ....

[@mr.b3168]

These are the exact same symptoms on my 64 impala. Will try that later to see if it is my voltage regulator. I have dim lights, my batter is at 11.6 Volts(Brand new) even when car runs. Ive been messing with my headlights all day thinking that was the issue. But now that I see my volts are low, it might be Alternator or Regulator. Will come back with report

[@puremayhemFTW]

So what was it?

[@mr.b3168]

@@puremayhemFTW Two things. One... I got a new high output regular, just cus I was adding air bag compressors and subwoofer. My headlights still dimmed. I learned that in older cars, routing of the wiring caused it to lose voltage /amps /watts since the wiring was so long. So I did a relay kit which basically allowed for a wire to connect to lights directly from battery. And the old wire activated the relay that allowed current to pass to headlights.

[@charaznable2379]

full field engaged

[@amandamount9451]

Got that straight 6 sounding like a V8. Nice

[@Gulfshoreman]

Great video! I have a question though. Are you check all votages with the exception of the positive terminal on the alternator and the brown wire on the regulator harness at the battery? Thanks!

[@spockistheman]

Thanks a bunch! I tried this on my 68 Camaro and found out my regulator isn’t working.👍👍

[@jopa4012]

You just saved me 160 dollars! Thank you so much :D Johnny

[@emcewen]

Great tutorial!

[@Sublimelime7]

I've been having the opposite issue where testing at the battery and alternator are reading between 15-15.2 volts. A little high and my assumption was overcharging. I go to look at the voltage regulator and notice that only 2 wires are going into it. The 1 and 3 wire or "f" and 3 wire. There is not even a 'regulator' wire ran from the regulator to the alternator.

[@michaelrush1997]

I was having this problem on my 1970 c10 found the regulator was mounted to the radiator support and was grounding its self out it needs rubber grommets and not be bolted straight to metal. Just my problem runs fine now.

[@colemadden9300]

Michael Rush i really hope thats my problem

[@HootOwl513]

Actually it's not a grounding issue, because there's a small black ground lead that screws into the side of the EVR to ground it. The EVR is isolated with rubber grommets to shield it from body/engine vibration. Being a machanical device, bumps could make false contacts.

[@4dirt2racer0]

i kept having trouble with regulators n wanted more power anyway so i jus switched to a single wire its soo much easier cleaner lookin with less wires more efficient easier to wire less change of a connection or wire goin bad, its jus the way to go its cheap simple n really common also jus google it

[@bonbolino14]

Very helpful. Thanks Jonny

[@colemadden9300]

i did the same thing it worked when i bypassed it but the new voltage regulator that i put in still isn’t do anything

[@HOGSIDESJTV14BOSSHOGRECORDS]

Good vid folks 💯🍻

[@cardude6617]

What if brown wire is reading zero and red wire reads 12?

[@dalewilson4062]

I have a 72 Mustang I put a new ignition switch on it the old one was burn up.. with a new Interstate Battery At 12.4 charge I turn the key switch on the volts read a constant 11.85 and when its running 11.85 when its not running it goes back to 12.4.... I disconnected the voltage regulator did the test with a jumper wire started her up volts go to 13 + normal ...so im thinking the alternator is fine regulator bad ....I replaced the regulator several time's but still have same problem...I had replaced the fuse box interior wiring a while back with an identical wire harness ( used wiring but same part number) Pulled all my fuse's in the fuse box started it up still has 11.85 volts....I didnt think it could be the wire harness being I pulled all the fuses,,,,its now sitting at 12.4 volts ... any Ideas ????

[@davewhitman5392]

Darn good video

[@Rolexwearer]

Great info... what if its is over charging? Getting 15.3 volts at the battery when the engine is running.

[@doublewrench69]

BookerTSlurpeeCups hmmm. Check the third terminal on that voltage reg plug, it is used to sense voltage and I’m pretty sure if it has an issue the alternator is allowed to run wild and overcharge

[@Rolexwearer]

@@doublewrench69 thank you Sir...👍

[@doublewrench69]

BookerTSlurpeeCups hopefully poking around there gets ya somewhere because that’s all I can think of!

[@Rolexwearer]

Ended up being the voltage regulator...

[@AlexTorres-ks6kz]

My issue is I have nothing at the brown wire , how can I get power there?

[@dale3645]

For a 67 Camaro it has these wires: Blue - white - orange - black F 2 3 4 I believe that the Orange wire is connected to red wire of alternator? What 2 wires excite alternator? Thanks in advance!

[@johnng4139]

I have a 71 350 camaro. I changed both alternator and voltage regulator. The alternator still isn't kicking in. :(

[@frederickgarbutt5ive146]

What happens is you brig the voltage regulator to long? Does it not do that even if it working properly?

[@iVolkswagen]

Very good video, thank you

[@asiasmaster]

My 1967 firebird new alternator gen light stays on after turning car off also new regulator

[@richhidalgo8567]

My red wire shows 12v but the brown ,blue and yellow wire show no voltage when car is on. Where do I go from there?

[@chriscraft77022]

damn good video.. where did you find voltage regulator for 17 dollars? .. leaving that wire connected doesnt hurt anything.. just dont leave it connected and walk away from the vehicle for over a few hours.. it drains the battery..

[@doublewrench69]

Chris Craft rockauto! And it’s been mint ever since!

[@chriscraft77022]

@@doublewrench69 i have bought and saved so much money from them but it never crossed my mind.. people buy those things all day and night for $59.99 .. you should mention stuff like that in your videos..

[@doublewrench69]

Chris Craft thanks, if you’re in the market for a voltage reg right now they’re having a wholesaler closeout, one that’s normally $38 is $8! Might pick one up with tomorrow’s order just to have on hand when rescuing old junk. I don’t even want to think about what I would’ve spent at a parts store buying what I have at Rockauto!

[@chriscraft77022]

@@doublewrench69 i convert all mine over to internally regulated.... but thanks for the info.. check out my channel.. i started off in 2015.. i had a 67 c10 i built before i thought of getting on youtube.. my brother has a 72 that ive been trying to get over here to make a killing on videos.. .. keep making videos on the truck.. you can get a decent channel going.. just stick with the truck

[@CS-bw8pt]

Most important part of this entire video is missing. Where is your red test lead when you say “boom” ???

[@johnc6944]

great video

[@Fritsvrolijk]

Thanks Pro

[@oscarlabarca5371]

Tks

[@xja6716]

Nice video, I have an issue little different than yours, when I measure the voltage directly from the battery or from the alternator im getting 14.0 to 14.6 volts but a seconds later the voltage starting to fluctuating between 14.6 to 2 volts or so, do you know what can cause this fluctuation?

[@anarchyamp]

Good video

[@jesseespino7532]

are these steps also work on the 1977 ford f250?

[@bikeclochard]

Thx for the video! During your test at around 1:35 , which wire are you testing at the regulator connector?

[@doublewrench69]

bikeclochard I believe it was the blue wire!

[@bikeclochard]

@@doublewrench69 Thank you!

[@1977rubper]

Hi sir, what is the inline tube in the voltage regulator used for?

[@Baby_Suge]

Does a bad voltage regulator drain the battery?

[@domecrack]

1:29 WHICH WIRE?

[@domecrack]

2:47 WHERE TF IS YOUR RED TEST LEAD?

[@domecrack]

Welp, it was the regulator. Thanks for these vague but ultimately useful instructions.

[@MainSportsman]

Awesome, Found a loose wire at the regulator... Thanks.

[@93jake81]

Is the voltage regulator always supposed to be powered up even with the key off? The voltage regulator on my dads 67 mustang gets warm even with the key off and it’s overcharging the battery

[@doublewrench69]

Jake Wright I haven’t heard of that problem before but I believe they should be fed through the ignition, thus off when the key is off. If his wiring isn’t messed up maybe his ignition switch is? That shouldn’t happen

[@93jake81]

DoubleWrench ok thanks. We’re getting a new wiring harness for it since the wiring is messed up and he doesn’t trust it

[@doublewrench69]

Jake Wright that’s probably it. In 50+ years who knows how badly the wiring has been botched!

[@stuckinmygarage6220]

Thank you for the principle of the shorted wire. You are turning "on" the alt? The regulator is supposed to do that, right? You have a brand new alt. Was that because you lost the alt due to the regulator? :-)

[@yafois988]

Didn’t quite see the first wire you trusted on wire harness end, IO presume it was the orange one

[@doublewrench69]

Cloud IS behind Sun I believe that was the blue wire

[@yafois988]

@@doublewrench69 In bit Im going out to do some testing, blue is that is “F” or “FIELD“ coils winding connected to the diodes.

[@logancollins100]

My 64 dies when i unplug the voltage regulator to test it. Any ideas?

[@doublewrench69]

ThisGuy hmm, my first thought would be is your battery good?

[@logancollins100]

Honestly i could use a new one. Ill get one today. I know the alternators good as its putting out 14.4. Ill give a new battery a shot

[@logancollins100]

Just replaced the battery. Still seems to have the same issue. Alt is outputting 14.5 to battery as well

[@richardcrainium7056]

It would be helpful of instead of saying blue wire white wire how about you call it f terminal aterminal s terminal.

[@quincyvalencia594]

🤌🏽