'66 C10 Alternator not charging Battery

[66c10lwb]

Have new alternator, new external regulator installed and good charge on Battery and I have had it checked. Alternator was checked and passed as well. Have verified all wiring per the wiring diagram and did continuity check on all wires with good results.
With Key on / engine on the generator light is on. Checked with meter and see no signs of battery charging.
Has anyone encountered this?

[VetteVet]

make certain that the voltage regulator is grounded to the radiator support and that the alternator is grounded to the engine block. The regulator is mounted in rubber grommets
so it should have a wire connected between it and the support.

[66c10lwb]

Thanks Vette. Questions regarding the regulator firewall mounting and alternator grounding.
1. Should the rubber grommets isolate the regulator metal frame from coming into direct contact with the firewall so that the single wire from the back of the regulator is the only contact to the firewall?
I noticed the previous regulator (which was bad) was on the grommets on one side of the firewall but the screw head on the opposite side of the firewall were not.
2. The negative battery post cable is attached to the Alternator bracket and a wire from the negative battery post is attached to the chassis.
Is this adequate or is there a better method?

[VetteVet]

Originally Posted by 66c10lwb

Thanks Vette. Questions regarding the regulator firewall mounting and alternator grounding.
1. Should the rubber grommets isolate the regulator metal frame from coming into direct contact with the firewall so that the single wire from the back of the regulator is the only contact to the firewall? Yes the grommets keep vibrations down and they prevent resonance through the firewall and cab from the coil operation inside them. The wire is there to ground the regulator to the radiator core support.
I noticed the previous regulator (which was bad) was on the grommets on one side of the firewall but the screw head on the opposite side of the firewall were not.
2. The negative battery post cable is attached to the Alternator bracket and a wire from the negative battery post is attached to the chassis.
Is this adequate or is there a better method?

If the engine starts then the engine is grounded but there might be some paint on the alternator mounts. Chances are that the alternator is grounded ok. you could check with a multimeter from the alternator body to the negative battery post for continuity to be certain. Then check from the regulator body to the negative battery post for the same thing. Make sure you have continuity from the regulator plug to the alternator for the large red wire and the blue and white wires. The red wire is hot at all times so don't hook the meter to it on the Ohms scale. Use the volts scale and check for 12 volts on the large red wire on the alternator and also on the large red wire on the regulator. Also check for about 3 volts on the brown wire that goes to the regulator with the key on.

[66c10lwb]

Thanks for the info. Vette. I ohmed my wires out this morning and took the battery out of the check. I read between 300 to 500mA depending on which wire I checked. I'm going to replace the horn relay and make sure its ground screw is making good contact.
If it still doesn't work I'm outta ideas.

[raycow]

Leave the horn relay alone. It has no effect on the alternator charging.

First, unplug the two-wire connector at the alternator. Turn on the ignition. The warning lamp should be off and there should be voltage at the R terminal of the connector. If good, plug in the connector.

At the regulator, check for battery voltage on terminal #3. If good, connect a jumper across terminals 3 and F. You will need to do this with the wire connector still plugged into the regulator. Now start the engine, and DO NOT run it above idling speed. If the alternator starts charging now, the regulator is probably bad. If not, the problem is in the alternator or connecting wires.

To check the wiring, you can repeat the same test at the alternator. First, check for voltage on the BAT terminal. If good, jump from the BAT terminal to the F terminal on the plug-in connector (still plugged into the alternator).

This test applies full battery voltage to the field winding, effectively taking the regulator out of the charging circuit. Don't leave the jumper connected any longer than necessary to run the test.

This diagram may help you see what you are working with.
http://www.alternatorparts.com/GM_ex...ng_diagram.htm

Ray

[VetteVet]

here's a diagram for you. Until you get the 3 volts on the brown wire at the regulator, none of the other tests will do you any good.That's the wire that turns on the alternator.

[66c10lwb]

Ray Thanks. Did not know to do these tests. I looked at the diagram you gave the link to and a question is the ground wire from the alternator to the case of the Voltage Regulator? The diagram for a '63 I have shows this wiring but the '66 diagram doesn't. Much like the one Vette attached.
Ken

[66c10lwb]

Also, With Key on engine off I'm getting battery voltage little over 12V not 3V @ the brown wire unplugged from regulator.

[VetteVet]

Originally Posted by 66c10lwb

Also, With Key on engine off I'm getting battery voltage little over 12V not 3V @ the brown wire unplugged from regulator.

That might be the difference between the two style dashes but I know there must be voltage there. Is your horn relay in the engine compartment or in the cab by the fuse box?My 67 is in the cab and The cars relays were in the engine compartment. I don't know about the pre-67 trucks. As you can see by the diagram I posted, the relay is used as a junction for the red power wires from the battery, alternator, and regulator. If you had a bad connection there it would affect the charging.

[66c10lwb]

Yes, my relay is on the radiator support by the regulator. Mine also has the Battery, Alternator and Regulator red wires routed through it. Along with the wiring diagram link Ray posted above and this one, http://rmcavoy.freeshell.org/Truck_gauges.html
which I've been using to reference the '66 wiring diagram for tracing everything out. Different from the one in the link Ray provide here are my ignition switch wires:
BAT-Red
ACC-Brown/White
IGN-Pink
GRD -Dark Green
SOL-Purple
I have the ACC-Brown /White, SOL-Purple and GRD -Dark Green left to check out. The ACC-Brown /White being an important one with the "resistance wire" inline. So far everything follows the wiring diagram.
If I ohm out the ACC-Brown/White wire with the resistance wire in it would that help identify if it is in good condition? not sure about that one.

[RichardJ]

Can we go back to the top?
A fully charged battery should have 12.5 - 12.6 Volts when checked with a volt meter. When you start the engine, the alternator should be able to produce 13 - 14 Volts AT the battery.
>>Checked with meter and see no signs of battery charging.<< I am weak at reading between the lines so could you give a little more detail.


The rubber isolators are called Well Nuts http://http://www.lowes.com/SearchCa...+nuts&x=29&y=5 are there to isolate the regulator from VIBRATION. As was pointed out, the base of the regulator must have an electrical ground. A short wire connected to the regulator base and the sheet metal near by.

It is seldom a good idea to check automotive grounds with an ohm meter. Using the low voltage scales on your voltmeter, you check the voltage from the negative post on the battery to the metal base of the regulator. Make this check with the engine running. The reading you get should be around .2 Volts (read point 2 volts) or probably the same reading you get when you short the two test leads of the volt meter together. IF you have a bad ground, you will get a reading possibly as high as battery voltage.
Use the same test method for checking other grounds. Measure battery neg post to engine, to body and to frame.
Everything in your truck relies on a COMMON GROUND. Rust, paint, loose bolts screw that up.

Please do not use the term "ohm out" or "ohmed". Do you remember the movie "Hitch", where Hitch slapped Albert Brenaman for dancing like geek that had been tasered? Please don't make me want to slap you.

[raycow]

Sorry, I mistyped in my previous post. When I said to check for voltage at the R terminal of the alternator connector, that should have been the F terminal. There should not be any voltage on the R terminal.

My diagram is generic. The one posted by VetteVet should be ok. I changed my 60 from a generator to an alternator and did not use a ground wire. My alternator just grounds through the mount.

12 volts on the brown wire (ignition switch on) when unplugged from the regulator is ok. This is the same power you are seeing at the F terminal of the alternator (from the switch through the warning lamp). I just said to check it at the alternator to confirm continuity through the regulator and blue wire. When you plug the connector into the alternator the voltage will drop.

Btw, if you unplug the regulator connector, the warning lamp should go out, just as if you unplugged the alternator connector.

This diagram shows what is inside the regulator.
http://www.rowand.net/shop/tech/imag...-1970Buick.jpg

Ray

[geezer#199]

subscribed

[stellar]

check the guage fuse. If key on engine on lite on and alt IS charging the fuse may be the problem. If it is the problem you will have key on engine off no charge lite.

[VetteVet]

Originally Posted by stellar

check the gauge fuse. If key on engine on lite on and alt IS charging the fuse may be the problem. If it is the problem you will have key on engine off no charge lite.

What Fuse?

Here is how the lite works. http://www.alternatorparts.com/under...lternators.htm

66 c10lwb you would be much better off to convert to an internal regulated alternator.
http://67-72chevytrucks.com/vboard/s...d.php?t=119379

[stellar]

usually fuse is marked guages

[VetteVet]

Originally Posted by stellar

usually fuse is marked guages

I'm not sure on the pre 67s but the fuses on 67 and later are marked cluster feed and pnl lights. In any case the diagram below is for a 64 and I believe it covers a 66 as well. Notice the idiot lights are all fed by a 20 gauge pink wire from the ignition through the fuse panel. It seems to me that if a fuse was blown it would affect all the lites. I am assuming that he has an idiot lite dash and the only gauge is the fuel gauge which is still fed by the same pink wire.

[66c10lwb]

UPDATE:
First: Thanks to all who replied with help, especially Ray and Vette. Ray for his trouble shooting steps and wiring link and Vette for his too.

Going through the trouble shooting steps from Ray and Vette and some online searches I have narrowed it down to the Voltage Regulator. The ones provided from the local auto parts stores were not working. After determining this is the weak link, which I'll give an expanded write-up after I verify this last attempt, I did an online search for the correct voltage regulator (More of a quest) and found direction from other forums that were dealing with the same issue.
I found that the recommended VR for my vehicle is the AC Delco D635. Could not find one of these locally. Found it through Amazon. More surfing online turned up a manufactures cross reference list.

Here is a listing of other manufacturers equivalent to the Delco D635.
Standard Ignition part # VR-103
Borg Warner part # R281
Niehoff part # DR153B
Echlin part #VR142
Filko part #VRD459
Wells part # VR715
Kem part # KVR172
GP part # VR273

I located one of these (Echlin part #VR142) at a Napa auto parts store. On a side note, It's been awhile since I've been out in the garage working on, restoring or fabricating anything. Once the rust was knocked off I rediscovered the a availability of many auto parts stores locally is a great asset. It brings new meaning to instant gratification.

So, it's Saturday morning and I'm off to get the voltage regulator. Will post the results later on.

Ken

[66c10lwb]

Problem solved. Switched to internal regulated alternator. It works. Disappointing that I couldn't get the original setup working though.

[joeb]

Originally Posted by raycow

Leave the horn relay alone. It has no effect on the alternator charging.

First, unplug the two-wire connector at the alternator. Turn on the ignition. The warning lamp should be off and there should be voltage at the R terminal of the connector. If good, plug in the connector.

At the regulator, check for battery voltage on terminal #3. If good, connect a jumper across terminals 3 and F. You will need to do this with the wire connector still plugged into the regulator. Now start the engine, and DO NOT run it above idling speed. If the alternator starts charging now, the regulator is probably bad. If not, the problem is in the alternator or connecting wires.

To check the wiring, you can repeat the same test at the alternator. First, check for voltage on the BAT terminal. If good, jump from the BAT terminal to the F terminal on the plug-in connector (still plugged into the alternator).

This test applies full battery voltage to the field winding, effectively taking the regulator out of the charging circuit. Don't leave the jumper connected any longer than necessary to run the test.

This diagram may help you see what you are working with.
http://www.alternatorparts.com/GM_ex...ng_diagram.htm

Ray

Ray,
I was reading this post from you from some time ago. I am new here and I just started working on my newly acquired 64 C10.

You mention that after the two wire plug is disconnected from the back of the alternator, the GEN light should be OFF and that there should be battery voltage at the F terminal of the alternator plug.

I have done this, but both items you mention are not right. The GEN light is still on and there is no voltage at either to the terminals when unplugged from the alternator.

Can you provide any input on what to check from here?

[srziemkowski]

Had the same issue with mine when i got it,alt not charging,po had both internal regulator altenator and external regulator both wired,disconnectoed external,problem solved.

[VetteVet]

Originally Posted by 66c10lwb

Also, With Key on engine off I'm getting battery voltage little over 12V not 3V @ the brown wire unplugged from regulator.

This was my bad on the 3 volts as I was shooting from the hip and not thinking about the math. The resistance (10 ohms) really don't drop the voltage much so it should still be 12 volts. I hope this didn't confuse anyone.

Had the same issue with mine when i got it,alt not charging,po had both internal regulator altenator and external regulator both wired,disconnectoed external,problem solved.

Interesting to say the least.

[joeb]

I have been working on this for some time now. I followed the suggestions by VetteVet but nothing worked.

I kept thinking this has to work, this worked at one time so it should work now.

Suffice it to say, I followed the last suggestion by VetteVet...I got an alternator with an internal regulator yesterday.

Part of my brain still wants to make the original setup work again.

[studeclunker]

I see this is a really old thread. However I am coming up with the same problem. Hopefully this will ping someone knowledgeable's radar?

However I changed out the old regulator when the newer alternator quit and I replaced it (regulator) with a Standard VR-103. the new alternator is internally regulated. Should I have bypassed the regulator and is some kind of rewire needed for everything to work?

I thought my battery was bad and bought a new one. However I came out to my truck a week later and dead battery. So obviously, the battery isn't charging?

Would just unplugging the regulator work?