The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > General Truck Forums > Electrical

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 12-24-2017, 12:28 PM   #1
Rac65
Registered User
 
Join Date: Aug 2011
Location: Shepherd, Texas
Posts: 57
Charging issues

I have a new alternator and voltage regulator and all my wires seem to be good but with the engine running voltage at the battery is only 12 volts. I took the alternator back to Auto zone to have it tested and they say it is good. I can put my meter on the post on the back of the alt. With it running and it still only shows 12 volts. Any advice on what to do next?
Rac65 is offline   Reply With Quote
Old 12-25-2017, 06:37 PM   #2
mikie 1954
Registered User
 
Join Date: May 2009
Location: caliente ca.
Posts: 290
Re: Charging issues

put this in the electrical section, you will find good people there that know their stuff.
mikie 1954 is offline   Reply With Quote
Old 12-25-2017, 09:31 PM   #3
franken
Registered User
 
Join Date: Jun 2013
Location: Somewhere
Posts: 2,147
Re: Charging issues

Just measure across the battery and post the voltage (to the nearest tenth, as in 12.6V) not running, running at idle, and at a few thousand RPM.
franken is offline   Reply With Quote
Old 12-26-2017, 01:33 AM   #4
Captainfab
60-66 Nut

 
Join Date: Mar 2007
Location: Coeur d'Alene, Idaho
Posts: 21,154
Re: Charging issues

It sounds like either the alternator or the voltage regulator. These days, buying new parts does not necessarily mean that are going to work correctly.
__________________
Power Steering Box Adapter Plates For Sale HERE
Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE
Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE
Hydroboost Mounting Plates HERE
Captainfab is offline   Reply With Quote
Old 01-07-2018, 05:00 PM   #5
Rac65
Registered User
 
Join Date: Aug 2011
Location: Shepherd, Texas
Posts: 57
Re: Charging issues

I had the alternator and voltage regulator tested at the local auto electric shop and they both tested good. I guess I will check the wiring next . I glanced at it and didn't see anything obvious.
Rac65 is offline   Reply With Quote
Old 01-07-2018, 06:42 PM   #6
Nanook
Registered User
 
Nanook's Avatar
 
Join Date: Feb 2016
Location: Georgetown, TX and Priddis, AB
Posts: 135
Re: Charging issues

Might be obvious, but is the belt tight?
Nanook is offline   Reply With Quote
Old 01-08-2018, 07:23 AM   #7
ImpalaJim
Registered User
 
ImpalaJim's Avatar
 
Join Date: May 2014
Location: Kewanee IL
Posts: 255
Re: Charging issues

I tried to get a regulator tested and they told me cant be done
ImpalaJim is offline   Reply With Quote
Old 01-11-2018, 03:13 PM   #8
vince1
Registered User
 
Join Date: Jan 2013
Location: Calgary Alberta
Posts: 718
Re: Charging issues

Yup, the electrical guys will probably show you a wiring diagram of how it is supposed to work. I suspect you are not getting voltage to somewhere on the regulator or on the up side the regulators for these things are dirt cheap. Mine was overcharging and from someone on this forum I found that it was probably a bad ground between the regulator and alternator and it was. In the end I had an extra alternator with internal regulator which I used and donated the original to a local re-builder.
vince1 is offline   Reply With Quote
Old 01-12-2018, 12:39 AM   #9
Captainfab
60-66 Nut

 
Join Date: Mar 2007
Location: Coeur d'Alene, Idaho
Posts: 21,154
Re: Charging issues

Is the regulator grounded?
__________________
Power Steering Box Adapter Plates For Sale HERE
Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE
Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE
Hydroboost Mounting Plates HERE
Captainfab is offline   Reply With Quote
Old 01-13-2018, 02:27 AM   #10
VetteVet
Msgt USAF Ret
 
VetteVet's Avatar
 
Join Date: Jan 2005
Location: Kalamazoo, Michigan
Posts: 8,099
Re: Charging issues

Quote:
Originally Posted by Rac65 View Post
I have a new alternator and voltage regulator and all my wires seem to be good but with the engine running voltage at the battery is only 12 volts. I took the alternator back to Auto zone to have it tested and they say it is good. I can put my meter on the post on the back of the alt. With it running and it still only shows 12 volts. Any advice on what to do next?
Pull the small plug off the back of the alternator and check the white wire with your meter. Key off--zero volts Key on--12 volts.

The blue wire should show 12 volts with the key on or off.

Make sure the alternator is grounded, the regulator is grounded to the shroud and connected to the alternator.

Name:  1964--66 chevy truck help pictures 018.jpg
Views: 136
Size:  50.6 KB
__________________
VetteVet

metallic green 67 stepside
74 corvette convertible
1965 Harley sportster
1995 Harley wide glide

Growing old is hell, but it beats the alternative.
VetteVet is offline   Reply With Quote
Old 01-13-2018, 10:06 AM   #11
my56chevytruck
Registered User
 
my56chevytruck's Avatar
 
Join Date: Feb 2016
Location: Hebron
Posts: 623
Re: Charging issues

Have you checked all your grounds?
my56chevytruck is offline   Reply With Quote
Old 01-25-2018, 10:52 PM   #12
Wrenchbender Ret
Registered User
 
Join Date: Oct 2005
Location: Lenexa, Kansas
Posts: 4,559
Re: Charging issues

Take the connecter off the regulator. Put a jumper wire from the blue wire connector to the red wire. You should get a small blue spark when you make & break the circuit. Start the engine & check the voltage. If the voltage goes up it means the alt. is good & the problem is in the reg. or wire ing.
Wrenchbender Ret is offline   Reply With Quote
Old 01-27-2018, 03:04 PM   #13
NicholasRivera34
Registered User
 
Join Date: Nov 2017
Location: Los Angeles CA
Posts: 5
Re: Charging issues

Check the tension on the alternator belt. Also double check your grounds. I would suspect the alternator over the regulator. But you said that tested normal...
NicholasRivera34 is offline   Reply With Quote
Old 01-29-2018, 01:11 PM   #14
robertsjm711
Registered User
 
robertsjm711's Avatar
 
Join Date: Jul 2017
Location: Lebanon, Oregon
Posts: 219
Re: Charging issues

Well here is my 2c...

Make sure the regulator is getting ignition signal (and batt., & continuity to alt.) - I had one that had a faulty wire

Also while revving up the engine a little, ~2000-2500 rpm, check voltage- if it rises to ~13.5v then it may be as simple as a wrong size pulley

If all else fails replace the regulator - I think they are pretty cheap and it would at the very least eliminate it from being a possibility
__________________
It was said that if you cut off one hydra head, two more grow back.
-Lernaean Hydra

Build Thread:
http://67-72chevytrucks.com/vboard/s...d.php?t=743246
robertsjm711 is offline   Reply With Quote
Old 01-29-2018, 06:13 PM   #15
LH Lead-Foot
Registered User
 
LH Lead-Foot's Avatar
 
Join Date: Jan 2018
Location: Omaha, NE.
Posts: 62
Re: Charging issues

In the photo posted by VetteVet, it appears to be a Delco 10SI. Identification is crucial first, but if this is your alternator, the regulator is internal AND yes, it has to be grounded. Use the un-used threaded bolt hole and provide a 10 AWG to the engine. I like using star washers on eyelets. The top connector has a small "D" shaped hole under it as pictured. The regulator provides ground to the stator, this is a test window. With engine running, carefully place a pocket screw driver into the hole to touch the case & tab from the regulator. Rev up the engine as you should hear a little whine. Your DMM should show 13.8 - 14.2Vdc. Let's figure out what you have first and what you need to do. The "F" terminal is hot thru the key on, going thru the charge lamp. Depending on the year, they place a 460 ohms resistor in parallel with the lamp to maintain the charging circuit if the bulb goes out. The field coil is the "Y" connect type. The center connection has no voltage if not working. When it is running & working, it provides B+ to the dash lamp. With B+ on both sides of the lamp, it goes out. If their is issues with a diode or something in the alternator, the lamp comes on dim. I have used this terminal to run the electric choke.
Do you have a DMM or analog meter? Are you looking at the dash gauge or meter? Are the battery cable ends clean where the sun does not shine? Are there good ground cables from the battery to engine & chassis? Let's start there with some answers. I taught 31 different classes, 6 of those being electrical classes for ACDelco, with #6 being lab scopes.
As for wire size (AWG) yes, current is measured in amps, but the length of the circuit determines the size of the wire. Most 4 -10 amp circuits operate with 20 gauge wire on GM's the last 30 years. As for a good relay/fuse center, go for the passengers side IP relay center from Buick LeSabre, Park Ave thru 1990-1999. Older one had 0.250" relay terminals, then they switched to "Micro" relays using 2.80m or called 280. The relay/fuse center is behind the glove box, with the ECM, theft module (Pass-key) and lamp module and is rectangular in shape while locations for 12 relays & 12 fuses. Good bone yard find for $10 of less.
LH Lead-Foot is offline   Reply With Quote
Old 01-29-2018, 09:15 PM   #16
VetteVet
Msgt USAF Ret
 
VetteVet's Avatar
 
Join Date: Jan 2005
Location: Kalamazoo, Michigan
Posts: 8,099
Re: Charging issues

The alternator I pictured is a 10 DN used on 67 to 74 gm vehicles specifically our
trucks. They use an external regulator as the OP states that he has. Converting to an internally regulated alternator 10/12 SI is very easy, or even up to a CS style. I've detailed the conversion many times her on the forum.

The internal regulated alternators do not require a separate ground like the one I pictured since the regulators are grounded to the alternator case. Grounding is managed just by bolting the alternator to the engine block with clean mounts of course.

The instructions in post 12 by Wrenchbender Retired, will full field the alternator, and a voltmeter connected as instructed should give a reading of up to 16 volts. The small D shaped hole in the 10 dn will also full field the alternator if a small screwdriver is inserted. Only do this for short periods less than 30 seconds, because it will overheat the alternator. Also it may over voltage and damage any loads in the circuits, so do not rev the engine with any lights on and do not rev the engine if the HEI distributor has been installed. This especially includes any digital goodies that are sensitive to over voltage.

Pictures of the 10 and 12 SI alternators.

Name:  DelcoAlternators.jpg
Views: 72
Size:  55.2 KB
__________________
VetteVet

metallic green 67 stepside
74 corvette convertible
1965 Harley sportster
1995 Harley wide glide

Growing old is hell, but it beats the alternative.
VetteVet is offline   Reply With Quote
Old 02-18-2018, 12:55 PM   #17
Rac65
Registered User
 
Join Date: Aug 2011
Location: Shepherd, Texas
Posts: 57
Re: Charging issues

Thanks for the info guys. I haven't fixed it yet but I am going out this afternoon to work on it . I have the old style alt. with the ext. reg.. Are they grounded when you bolt them on or is the ground wire from alt to reg required?
Rac65 is offline   Reply With Quote
Old 02-18-2018, 02:48 PM   #18
Rac65
Registered User
 
Join Date: Aug 2011
Location: Shepherd, Texas
Posts: 57
Re: Charging issues

I went out and started looking at wiring and connections. I took the red wire that runs from the battery to the other side where the regulator and horn relay are loose and wire brushed everything , put it all back and started it up. When I stuck my meter on the battery terminals it showed 14 volts . Must have been bad connections. Sometimes you overlook the simple things. Thanks for the advice.
Rac65 is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 08:27 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.
Copyright 1997-2013 67-72chevytrucks.com