70 Charging Issue - Page 3 - Chevelle Tech
Electrical & Wiring Troubleshooting electrical problems.

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post #31 of 55 (permalink) Old Jul 2nd, 19, 3:15 PM Thread Starter
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UPDATE: the 3rd alternator is in and.... nothing. 12.3v still.
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post #32 of 55 (permalink) Old Jul 3rd, 19, 1:11 AM
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Re: 70 Charging Issue

Does your alternator warning light work ? Does it turn on with the ignition key on/not running?

Is your regulator connected to bright shiny metal with bright shiny bolts? Is your regulator properly grounded?

If you disconnect the connector at the regulator, don't expect your regulator to charge at all. Nothing at that point is charging the field and there is no sense voltage so the alt will produce no voltage.
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post #33 of 55 (permalink) Old Jul 3rd, 19, 1:44 AM
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Re: 70 Charging Issue

To test your alt light, disconnect the connector at the regulator, turn on the ignition and jump brown #4 connector to ground. Your light should light. If it doesn't light we're on the path to resolution. Your bulb is burned out, or we have an open circuit with no power supplied from the ignition switch to the brown wire. So no charge. Does your temp light turn on when you turn on the key? Does the gas gauge work? Check all your fuses with a test light. Ground the lead and probe both sides of the fuse. Both sides light fuse, fuse OK.

If you disconnect the connector at the regulator, don't expect your regulator to charge at all. Nothing at that point is charging the field and there is no sense voltage so the alt will produce no voltage.

To test the alt alone, disconnect the connector and temporarily jump from the F terminal of the regulator plug to the 3 (orange or red wire) terminal with the engine running about 1500 rpm.
You should see about 15 volts at the alt output. Alt is good, you have wiring issues or regulator is faulty. I think you have a wiring issue.
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Last edited by DUTCH MAX HEADWORK; Jul 3rd, 19 at 2:09 AM.
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post #34 of 55 (permalink) Old Jul 3rd, 19, 1:47 PM Thread Starter
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Quote:
Originally Posted by DUTCH MAX HEADWORK View Post
Does your alternator warning light work ? Does it turn on with the ignition key on/not running?

Is your regulator connected to bright shiny metal with bright shiny bolts? Is your regulator properly grounded?

If you disconnect the connector at the regulator, don't expect your regulator to charge at all. Nothing at that point is charging the field and there is no sense voltage so the alt will produce no voltage.
Generator light? Yes it will turn on for just a second if I have to crank the IGN a few seconds.

Not shiny bolts, I can clean them up, the VR grounds through it's legs correct? Yes it's on freshly sanded surface metal.



Quote:
Originally Posted by DUTCH MAX HEADWORK View Post
To test your alt light, disconnect the connector at the regulator, turn on the ignition and jump brown #4 connector to ground. Your light should light. If it doesn't light we're on the path to resolution. Your bulb is burned out, or we have an open circuit with no power supplied from the ignition switch to the brown wire. So no charge. Does your temp light turn on when you turn on the key? Does the gas gauge work? Check all your fuses with a test light. Ground the lead and probe both sides of the fuse. Both sides light fuse, fuse OK.

If you disconnect the connector at the regulator, don't expect your regulator to charge at all. Nothing at that point is charging the field and there is no sense voltage so the alt will produce no voltage.

To test the alt alone, disconnect the connector and temporarily jump from the ‘F’ terminal of the regulator plug to the ‘3’ (orange or red wire) terminal with the engine running about 1500 rpm.
You should see about 15 volts at the alt output. Alt is good, you have wiring issues or regulator is faulty. I think you have a wiring issue.
All of my gauges work, my clock does not, nor does my overhead lamp. I'll have to check on temp light.
I've done the F-3 alt test and it works. I'll try the light test sometime today. Thanks.
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post #35 of 55 (permalink) Old Jul 3rd, 19, 1:54 PM
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Re: 70 Charging Issue

As stated earlier, if you have 12.3 volts at the ALT terminal on the back of the alternator then you have an alternator problem. There should be quite a bit more voltage there. High 13s to low 14s at least.

Take it off and have it tested at the parts store before you do any more testing or replacing of wiring.

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post #36 of 55 (permalink) Old Jul 3rd, 19, 2:57 PM Thread Starter
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Originally Posted by Greg Owens View Post
As stated earlier, if you have 12.3 volts at the ALT terminal on the back of the alternator then you have an alternator problem. There should be quite a bit more voltage there. High 13s to low 14s at least.

Take it off and have it tested at the parts store before you do any more testing or replacing of wiring.
You're saying, all plugs in, key on engine running, that I should get 13v+ at the alt terminal. Even if the VR isn't working properly.
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post #37 of 55 (permalink) Old Jul 3rd, 19, 9:26 PM
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Re: 70 Charging Issue

Now that I think about it, I have never had a VR go bad so I am actually not sure on that one. Did you say you have tried multiple alternators AND multiple VRs? If so, the chance of all of them being bad is nearly 0 so we need to be looking elswhere.

Technically alternators are supposed to be grounded. Typically the alternator bracket takes care of that for you but corrosion or powder coated or painted brackets can interfere. You might want to rig up a test ground wire from the alternator housing to the engine or battery negative to see if that helps.

Do you have a good ground from the battery to the engine block?

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post #38 of 55 (permalink) Old Jul 3rd, 19, 10:24 PM Thread Starter
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Now that I think about it, I have never had a VR go bad so I am actually not sure on that one. Did you say you have tried multiple alternators AND multiple VRs? If so, the chance of all of them being bad is nearly 0 so we need to be looking elswhere.

Technically alternators are supposed to be grounded. Typically the alternator bracket takes care of that for you but corrosion or powder coated or painted brackets can interfere. You might want to rig up a test ground wire from the alternator housing to the engine or battery negative to see if that helps.

Do you have a good ground from the battery to the engine block?
Yes I've tried multiple of each. I put a fusible wire on my positive cable going to radiator wall. I've cleaned wires out the wazoo, and used a voltmeter everyway possible. I would just do cs130 upgrade but there's no point if it's a wiring issue.

On the grounds, I put a new one on the negative to passenger fender, but I can't find any others floating around.
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post #39 of 55 (permalink) Old Jul 3rd, 19, 10:58 PM Thread Starter
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Just checked my 4 ground locations.. and I only have the one I put in. Going to order a set of ground straps and hopefully they will get me fixed up. Can I just put a screw roughly where it goes in the firewall? I didn't see any bolts or holes in the vicinity of where they go.
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post #40 of 55 (permalink) Old Jul 4th, 19, 5:35 AM
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Re: 70 Charging Issue

Quote:
Originally Posted by Jlhook716 View Post
Generator light? Yes it will turn on for just a second if I have to crank the IGN a few seconds.

Not shiny bolts, I can clean them up, the VR grounds through it's legs correct? Yes it's on freshly sanded surface metal.





All of my gauges work, my clock does not, nor does my overhead lamp. I'll have to check on temp light.
I've done the F-3 alt test and it works. I'll try the light test sometime today. Thanks.
Is your car equipped with gauges or idiot lights? Is this an SS pod style dash? or a sweep dash? Sorry if I missed it in earlier posts. The SS light dash is in the attachment.

If your VR is mounted on clean metal it should be grounded sufficiently. There's a terminal on the bottom of the VR. It should not be grounded. If anything is connected it would be a one wire condenser. It's only job is to prevent radio interference.

Your alternator mounts and bolts should be clean at the mating surfaces. Your negative batt term should be bolted to a clean surface with clean bolts to the top of the alt bracket. The bolt should be tight. Sometimes they strip out, if this is the case, get a longer bolt and put a nut on the bottom side and tighten. The neg term can also be mounted on a bolt to the engine. The connector bolt and block should be clean and free of paint. If you really had a problem here, it would show up when you put a high load on the system like starting the engine.

More than likely your clock is toast. They wear out.

Dome light is powered by orange wire. It turns on when the other wire is grounded. It's on another circuit, we can mess with that later.

Did you check your fuses? Turn on the ignition and check for power at all fuses. The tiny "inst lts" fuse requires you to turn on the headlights and turn the rheostat brightness adjuster to the right just before the click. (I think if my memory is correct. I can check tomorrow)

****Check your GEN light operation. This will confirm or deny a closed circuit from the ignition switch through the gen light and out to the brown wire at the reg connector. Without this circuit, your alt will not produce power. Leave the connector connected to the reg. Turn the ignition switch 1 position forward to the IGN position. The light must be on and stay on if the engine is not running. If no light, turn the key off and slowly move the key forward and see if there is a position that the light will stay on at. Take it all the way to start. If there is a slight position where the light stays on be sides the detent IGN position, it tells us the IGN switch has a bad contact or is out of adjustment slightly.

Still no constant light? Remove the reg connector and temporarily jump the brown wire to ground. The light should light. If not, also suspect a bad connection in the bulkhead connector on the engine side of the firewall to the fuse box or burned out light.




This thread will show you the ground wire locations with pictures. https://www.chevelles.com/forums/27-...-chevelle.html
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post #41 of 55 (permalink) Old Jul 4th, 19, 10:03 AM Thread Starter
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Originally Posted by DUTCH MAX HEADWORK View Post
[

Is your car equipped with gauges or idiot lights? Is this an SS pod style dash? or a sweep dash? Sorry if I missed it in earlier posts. The SS light dash is in the

Did you check your fuses? Turn on the ignition and check for power at all fuses. The tiny "inst lts" fuse requires you to turn on the headlights and turn the rheostat brightness adjuster to the right just before the click. (I think if my memory is correct. I can check tomorrow)

****Check your GEN light operation. This will confirm or deny a closed circuit from the ignition switch through the gen light and out to the brown wire at the reg connector. Without this circuit, your alt will not produce power. Leave the connector connected to the reg. Turn the ignition switch 1 position forward to the IGN position. The light must be on and stay on if the engine is not running. If no light, turn the key off and slowly move the key forward and see if there is a position that the light will stay on at. Take it all the way to start. If there is a slight position where the light stays on be sides the detent IGN position, it tells us the IGN switch has a bad contact or is out of adjustment slightly.

Still no constant light? Remove the reg connector and temporarily jump the brown wire to ground. The light should light. If not, also suspect a bad connection in the bulkhead connector on the engine side of the firewall to the fuse box or burned out light.




This thread will show you the ground wire locations with pictures. https://www.chevelles.com/forums/27-...-chevelle.html
Sweep style dash. Glanced through fuses, haven't had time to put a meter on them. I'll try to tackle this today or tomorrow morning. Thank you
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post #42 of 55 (permalink) Old Jul 4th, 19, 3:09 PM
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Re: 70 Charging Issue

Jlhook,

If I am reading your post correctly the ONLY ground you have is a cable from the battery to the fender? If so then hopefully we have found the problem. Add a battery ground straight to the engine. Not sure where they were wired from the factory on a Chevelle but my Camaro had it going to the thermostat housing. You will also want to add a ground from the engine to the frame as well. Do that before you try anything else because if you have a grounding issue nothing else will help.

Your alternator is probably not putting out at all. The 12.3V you are seeing at the ALT post is just the battery voltage.

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post #43 of 55 (permalink) Old Jul 6th, 19, 12:44 PM
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Re: 70 Charging Issue

Going to throw in my $.02 worth.


Of all the cars I've restored, you have to have ground wires in 4 places other than the NEG battery cable.
1. NEG battery terminal to the passenger fender.
2. Ground strap from the frame to the body. This is under the heater box typically.
3. Ground strap from the right rear valve cover lower bolt to the firewall. I've seen these on the upper ones too.
4. Ground strap from the left rear valve cover lower rear bolt to the firewall. I've seen these on the upper ones too.


Here's a link to the 3 ground straps. IF you car hasn't been restored or modified. These straps should still be in place. Typically these get tossed during restores or engine work.
The short strap goes from the frame to the body. The 2 long straps go from the engine to the firewall. I've included the picture from the AIM.
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Last edited by Jayhawk500; Jul 6th, 19 at 12:59 PM.
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post #44 of 55 (permalink) Old Jul 6th, 19, 1:27 PM
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Re: 70 Charging Issue

I prefer a ground strap from the block to the firewall vs to the VC's.
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post #45 of 55 (permalink) Old Jul 6th, 19, 3:49 PM
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Re: 70 Charging Issue

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I prefer a ground strap from the block to the firewall vs to the VC's.
I like it too. Semi hidden like that. The chance for a better ground too. I also prefer to have my neg batt cable connect to a clean spot on the block with clean bolts. Always clean bolt holes and mounting points on alt bracket when I service the alt. Many alts have a bolt boss for addition grounding to the bock through a ground cable. This becomes more important with the larger output alts like the CS130 but still holds worthy on the smaller alts.

An area often overlooked is the mounting points at the regulator. They need to be clean and properly grounded. Without ground here you'll experience an overcharging system.
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