Possible Voltage Regulator Problem
April 22nd, 2015, 03:57 PM
#1
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Possible Voltage Regulator Problem
Greetings,
I have a 1970 Cutlass with a 350 2bbl. Last week I replaced the battery as the old one would no longer accept a charge. The car started up beautifully with the new battery installed. However, now there is a noticeable pulse of the headlights, gauge and interior lights when I give the car gas - at idle everything seems fine. The alternator is fairly new as well, and when I took the care to a local auto zone to have them test the alternator, they're tester said that the voltage regulator was the problem. I just want to make sure, would a voltage regulator on its way out cause the problem I've described or could it be something else?
Thank you,
Mike C
I have a 1970 Cutlass with a 350 2bbl. Last week I replaced the battery as the old one would no longer accept a charge. The car started up beautifully with the new battery installed. However, now there is a noticeable pulse of the headlights, gauge and interior lights when I give the car gas - at idle everything seems fine. The alternator is fairly new as well, and when I took the care to a local auto zone to have them test the alternator, they're tester said that the voltage regulator was the problem. I just want to make sure, would a voltage regulator on its way out cause the problem I've described or could it be something else?
Thank you,
Mike C
April 22nd, 2015, 08:50 PM
#3
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Location: southeastern Michigan
Posts: 14,208
I know that the standard argument is always to troubleshoot before throwing money at a problem. However, I would say this about your situation. You have already established that you have a good battery and apparently a good alternator. A check at the auto parts store suggests a new regulator is needed. A new voltage regulator for your car is about $28.00 at Autozone. Not exactly the cost of a gumball, but not exactly poorhouse-inducing either.
I was having symptoms similar to yours with my '67 Delta 88. The voltage at the battery at idle was about 12.5, which is low. The old regulator looked like it might have been original or at least installed back when Jimmy Carter was president. I put in a new one, and the voltage is now 13.5 to 14.5, which is where it should be. The car starts better now, too, as though the battery is more fully charged. I'm happy.
If it were me, I'd get a new regulator and throw it on. The job takes all of five minutes. The worst that can happen is that it doesn't fix your problem, but it can't hurt to put a new one on, anyway, if you know nothing about the history (age) of the one on the car now.
I was having symptoms similar to yours with my '67 Delta 88. The voltage at the battery at idle was about 12.5, which is low. The old regulator looked like it might have been original or at least installed back when Jimmy Carter was president. I put in a new one, and the voltage is now 13.5 to 14.5, which is where it should be. The car starts better now, too, as though the battery is more fully charged. I'm happy.
If it were me, I'd get a new regulator and throw it on. The job takes all of five minutes. The worst that can happen is that it doesn't fix your problem, but it can't hurt to put a new one on, anyway, if you know nothing about the history (age) of the one on the car now.
April 22nd, 2015, 09:07 PM
#4
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Before going to autozone, I went to a local advance auto parts store and the voltage test they did on the battery with the high beams on and the heat on was about 13.0. To the best of my knowledge, the current voltage regulator is the original one to the car. If I do replace it, and it does not fix the problem, granted I'm not out an outrageous amount of money or time, but what else could it be? I'll post again after it has been replaced and the problem not corrected.
Thank you all for your input.
Mike C.
Thank you all for your input.
Mike C.
April 23rd, 2015, 06:08 AM
#6
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Location: southeastern Michigan
Posts: 14,208
I'm curious as to why you're so negative on the idea that the regulator is the problem. You said that testing indicates it is, so it's not like you're replacing it on a whim. Yet you seem to believe that the test result is wrong.
By the way, I only mentioned Autozone as a place to get the new one because you mentioned in your first post that you went there for the testing. Advance Auto Parts is just fine, too, and if that's where you regularly do business, they'll have a regulator just as easily as Autozone will. It would probably be the same part.
I predict a new regulator solves your problem.
April 23rd, 2015, 09:51 AM
#8
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Join Date: Dec 2010
Location: Milwaukee, WI
Posts: 192
I've seen a failed diode in the "bridge" cause flickering lights, 'tho mainly at idle. A failed diode will reduce the alternator output which may be the cause of your charging problem. The typical auto parts store alternator test does not check for low rpm performance. A voltmeter can't follow the pulses to show a problem.
April 23rd, 2015, 10:20 AM
#9
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Posts: 7
Greetings,
Okay so today I went to the parts store (autozone) and bought a replacement voltage regulator. Hooked everything back up just as before and just as one problem gets solved another mystery starts. With the new regulator on, the lights no longer pulse when given the car gas, however now the generator light remain on at idle and turns off when the car is given gas. Any suggestions...
Thank you,
Mike C.
Okay so today I went to the parts store (autozone) and bought a replacement voltage regulator. Hooked everything back up just as before and just as one problem gets solved another mystery starts. With the new regulator on, the lights no longer pulse when given the car gas, however now the generator light remain on at idle and turns off when the car is given gas. Any suggestions...
Thank you,
Mike C.
April 23rd, 2015, 10:21 AM
#10
CH3NO2 LEARN IT BURN IT
Join Date: Jul 2010
Location: Land of Taxes
Posts: 4,871
Bad alternator, bad VR or bad connections in the system...Clean and tight connections on both the positive and negative sides of this system are required before you go any farther! Grounds are your friend in a negative ground system such as we all have on our vintage muscle.
When you start the engine a voltage is sent to the number ‘4’ terminal of the regulator, then it goes through the regulator, out the blue wire to the ‘F’ terminal of the alternator.
This energizes the field of the rotor and creates a spinning magnetic field inside the stator windings of the alternator. This starts the charging cycle. Now a small amount of voltage is sent back out the ‘R’ terminal of the alternator (white wire) to the number ‘2’ terminal of the regulator. This closes a set of points and allows the battery voltage from the red/orange wire to power the field circuit. If you have an idiot light it would now turn off. The amount of field current depends on the electrical load that is placed on the system. Now that the stator is producing current it will maintain the battery and take care of all the loads that are put on the electrical system.
Remember the battery is there to start the car and add current to the system only when the alternator is not producing enough to cover the electrical loads.
So if you have 37 amp alternator and you have 40 amps of electrical loads, then 3 amps will be supplied from the battery. This means the alternator has no current left to charge the battery and the voltage reading across the battery will be below 12.66v.
A properly working system should maintain a battery voltage of approximately 13.8-14.8 volts depending on temperature.
Always check charging volts with a fully charged battery and engine above 1000 RPM.
If the battery is very low when tested, then the charging voltage will be low. As the battery begins to charge then the charging voltage will rise.
A fully charged battery, after any surface charge is removed, will read ~12.66v.
Do you have any large loads say a huge stereo system?
Alternator/ regulator testing:
First, check for battery voltage at the stud where the large red or orange wire connects to the alternator. You should have battery volts. If not, repair the wire or circuit.
Then disconnect the plugs from the regulator and alternator.
Check the continuity of the blue (field) and the white (relay) wires between the plugs.
Repair any wire if they do not have continuity.
Reinstall the alternator plug and leave the regulator plug disconnected.
With a voltmeter, check voltage at the number 3 terminal on the regulator plug, it should read battery voltage. There should not be any voltage at the other three terminals at this time.
If you have voltage at the number 2 terminal, R on the alternator, you have a leaky diode in the alternator, replace the alternator. This will cause a battery drain and the regulator with be hot to the touch with the key off.
Now turn the key "on", you should have voltage at the number 4 terminal, this wire comes from the fuse panel. If you had an “idiot light”, this would be from the bulb.
This is what is called the exciter circuit, without voltage to this terminal the charging system will not begin to charge.
If no faults were found so far, leave the regulator plug disconnected, make sure all wires are clear of the fan and start the engine.
With a voltmeter connected to the battery and the RPM at approximately 1000-1200, jump from the F terminal of the regulator plug to the 3 (orange or red wire) terminal.
You should see an increase in voltage at the battery and hear the alternator working. If you hear a growling noise from the alternator you have either a bad diode or a bad stator winding.
Don’t leave the jumper connected too long because you don’t want the voltage to go over 15 volts for an extended period of time.
If you don’t see the voltage go above battery voltage after a few seconds then you have a bad alternator.
If the voltage rose quickly and then decreased this means you have a slipping fan belt.
Now connect a voltmeter to the number ‘2’ terminal (white wire) of the regulator connector and again momentarily jump from ‘F’ to 3. You should see about 8-10 volts.
If not, you have a bad diode in the alternator.
If all is OK up to this point reconnect the regulator connector.
If it is still not charging, run a separate ground wire from a good ground to the base of the regulator. Now if no there is still not charging, replace the regulator.
If you have an overcharging condition, it is either a bad ground at the regulator base or a bad regulator.
Look into the new solid state regulators. You can install a vintage Delco lid on these new regs and nobody will know.
When you start the engine a voltage is sent to the number ‘4’ terminal of the regulator, then it goes through the regulator, out the blue wire to the ‘F’ terminal of the alternator.
This energizes the field of the rotor and creates a spinning magnetic field inside the stator windings of the alternator. This starts the charging cycle. Now a small amount of voltage is sent back out the ‘R’ terminal of the alternator (white wire) to the number ‘2’ terminal of the regulator. This closes a set of points and allows the battery voltage from the red/orange wire to power the field circuit. If you have an idiot light it would now turn off. The amount of field current depends on the electrical load that is placed on the system. Now that the stator is producing current it will maintain the battery and take care of all the loads that are put on the electrical system.
Remember the battery is there to start the car and add current to the system only when the alternator is not producing enough to cover the electrical loads.
So if you have 37 amp alternator and you have 40 amps of electrical loads, then 3 amps will be supplied from the battery. This means the alternator has no current left to charge the battery and the voltage reading across the battery will be below 12.66v.
A properly working system should maintain a battery voltage of approximately 13.8-14.8 volts depending on temperature.
Always check charging volts with a fully charged battery and engine above 1000 RPM.
If the battery is very low when tested, then the charging voltage will be low. As the battery begins to charge then the charging voltage will rise.
A fully charged battery, after any surface charge is removed, will read ~12.66v.
Do you have any large loads say a huge stereo system?
Alternator/ regulator testing:
First, check for battery voltage at the stud where the large red or orange wire connects to the alternator. You should have battery volts. If not, repair the wire or circuit.
Then disconnect the plugs from the regulator and alternator.
Check the continuity of the blue (field) and the white (relay) wires between the plugs.
Repair any wire if they do not have continuity.
Reinstall the alternator plug and leave the regulator plug disconnected.
With a voltmeter, check voltage at the number 3 terminal on the regulator plug, it should read battery voltage. There should not be any voltage at the other three terminals at this time.
If you have voltage at the number 2 terminal, R on the alternator, you have a leaky diode in the alternator, replace the alternator. This will cause a battery drain and the regulator with be hot to the touch with the key off.
Now turn the key "on", you should have voltage at the number 4 terminal, this wire comes from the fuse panel. If you had an “idiot light”, this would be from the bulb.
This is what is called the exciter circuit, without voltage to this terminal the charging system will not begin to charge.
If no faults were found so far, leave the regulator plug disconnected, make sure all wires are clear of the fan and start the engine.
With a voltmeter connected to the battery and the RPM at approximately 1000-1200, jump from the F terminal of the regulator plug to the 3 (orange or red wire) terminal.
You should see an increase in voltage at the battery and hear the alternator working. If you hear a growling noise from the alternator you have either a bad diode or a bad stator winding.
Don’t leave the jumper connected too long because you don’t want the voltage to go over 15 volts for an extended period of time.
If you don’t see the voltage go above battery voltage after a few seconds then you have a bad alternator.
If the voltage rose quickly and then decreased this means you have a slipping fan belt.
Now connect a voltmeter to the number ‘2’ terminal (white wire) of the regulator connector and again momentarily jump from ‘F’ to 3. You should see about 8-10 volts.
If not, you have a bad diode in the alternator.
If all is OK up to this point reconnect the regulator connector.
If it is still not charging, run a separate ground wire from a good ground to the base of the regulator. Now if no there is still not charging, replace the regulator.
If you have an overcharging condition, it is either a bad ground at the regulator base or a bad regulator.
Look into the new solid state regulators. You can install a vintage Delco lid on these new regs and nobody will know.
April 23rd, 2015, 10:40 AM
#12
CH3NO2 LEARN IT BURN IT
Join Date: Jul 2010
Location: Land of Taxes
Posts: 4,871
Welcome!
Clean all the negative and positive connections on both ends of the battery cables. Start there. Do the cables look like they are in good shape? If not replace them (Fusick and Year One have the exact replacement cables dont use "will fits" from china).
Dont forget the little ground wire that comes off the negative battery cable at the battery. It needs to be cleanly hooked to the fender.
Inspect the wires on the reg and on the alt. Replace as needed.
The reg needs a good ground on the firewall.
There should be a ground strap running from the engine block or head to the firewall. Its generally a flat braided wire but any 12 and up gauge wire fabed up will suffice.
Then take the Alternator to a shop that specializes in them and have a real bench test performed.
If this is to much for you Id suggest finding a shop you feel comfortable with in your area that knows old cars. IMO Dont take it to one of the big box repair shops.
Clean all the negative and positive connections on both ends of the battery cables. Start there. Do the cables look like they are in good shape? If not replace them (Fusick and Year One have the exact replacement cables dont use "will fits" from china).
Dont forget the little ground wire that comes off the negative battery cable at the battery. It needs to be cleanly hooked to the fender.
Inspect the wires on the reg and on the alt. Replace as needed.
The reg needs a good ground on the firewall.
There should be a ground strap running from the engine block or head to the firewall. Its generally a flat braided wire but any 12 and up gauge wire fabed up will suffice.
Then take the Alternator to a shop that specializes in them and have a real bench test performed.
If this is to much for you Id suggest finding a shop you feel comfortable with in your area that knows old cars. IMO Dont take it to one of the big box repair shops.
April 23rd, 2015, 12:39 PM
#14
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Thread Starter
Join Date: Apr 2015
Posts: 7
All seems well now. I made sure the regulator was secure to the firewall, i had the clip from the radio capacitor between it and the firewall - possible bad ground; then I took a small wire brush and cleaned the terminals on the wire harness that goes into the regulator, especially the brown wire. Hooked it back up and the generator "idiot" light on the dash went off after start up.
Thank you to everyone for your advice.
Mike C.
Thank you to everyone for your advice.
Mike C.
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