18+ volts, other issues.
Thread Starter
Racer
Joined: Apr 2015
Posts: 412
Likes: 12
From: Carrollton, Georgia
18+ volts, other issues.
After installing all the autometer phantom gauges, and new flexalite fan, took the car put for a spin ( first time in a while and was really enjoying my self) well the car just shut off and I was stuck in the middle of the road. Well after a friendly fire truck helped me get off the road, replaced the coil in the distributor, and ignition module, and all seemed to be okay. I just drove the car and seemed to be OK, then I noticed that when I gassed it, volt meter would jump to 18+, and settle to maybe 14 at idle. Put a DVM on the battery and while giving it throttle it never got above 15 volts. Also noticed that the stud on the alternator for the power source has pretty much melted the plastic connection. Thoughts?
Thread Starter
Racer
Joined: Apr 2015
Posts: 412
Likes: 12
From: Carrollton, Georgia
Ok. My question is this. The plug in the alternator goes to the regulator, well I have completely bypasssed the wiring plug that goes into the back of the center gauge console due to the installation of the auto meters. Worried that I may be causing the issue inadvertently?
Le Mans Master
Joined: Aug 2006
Posts: 7,426
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
The voltage regulator is inside the alternator on a 77.
Are you referring to the horn relay or am I confused?
http://www.vetteprojects.com/bmv/mis...tte%201977.pdf
Are you referring to the horn relay or am I confused?
http://www.vetteprojects.com/bmv/mis...tte%201977.pdf
Thread Starter
Racer
Joined: Apr 2015
Posts: 412
Likes: 12
From: Carrollton, Georgia
The voltage regulator is inside the alternator on a 77.
Are you referring to the horn relay or am I confused?
http://www.vetteprojects.com/bmv/mis...tte%201977.pdf
Are you referring to the horn relay or am I confused?
http://www.vetteprojects.com/bmv/mis...tte%201977.pdf
Melting Slicks
Joined: Jan 2014
Posts: 2,478
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From: Downers Grove Illinois
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Race Director
Joined: May 2006
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The two wire plug is for the regulator. It is unclear what changes you made for the new gauges, be very specific. The fact that you are getting a 15 volt reading is a problem. Have the battery load tested and if it passes replace the alternator.
Thread Starter
Racer
Joined: Apr 2015
Posts: 412
Likes: 12
From: Carrollton, Georgia
Ok. I basically disconnected the large plug in the gauge console, took off the printed circuited board, and spliced into the pink wire for my power source, and spliced into the grey wire for lights, and then ran the sending units to the engine. For the volt meter gauge I just used the same pink wire and grounded it to the frame. My worry is the fact that I've pretty much disconnected the entire plug, and hope I am not effecting the voltage regulator by not using that plug
Le Mans Master
Joined: May 2007
Posts: 5,028
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From: North tonawanda NY
http://www.ebay.com/itm/ONE-1-WIRE-V...FV-xet&vxp=mtr
especially with the poor quality of the replacement alternators these days I would think rebuilding would be the better option...
Last edited by augiedoggy; May 9, 2016 at 05:44 PM.
Le Mans Master
Joined: Aug 2006
Posts: 7,426
Likes: 1,559
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
another option that makes more sense to me is to just rebuild the one he has for $9? ... takes like 10 minutes last time I did mine... Napa also stocks the parts locally.
http://www.ebay.com/itm/ONE-1-WIRE-V...FV-xet&vxp=mtr
especially with the poor quality of the replacement alternators these days I would think rebuilding would be the better option...
http://www.ebay.com/itm/ONE-1-WIRE-V...FV-xet&vxp=mtr
especially with the poor quality of the replacement alternators these days I would think rebuilding would be the better option...
Thread Starter
Racer
Joined: Apr 2015
Posts: 412
Likes: 12
From: Carrollton, Georgia
Thanks for all the help guys, but no one has answered my question about the aftermarket gauge wiring? Being that I have bypassed the wiring to the gauges, has that affected the wiring for the alternator. If im correct,that plug in the alternator controls the gen light, I know that the gen light is not longer being used, BC I no longer have a printed circuit board is that an issue? What about that other wire in the alternator plug?
Burning Brakes
Joined: Apr 2008
Posts: 1,222
Likes: 93
From: shelbyville West Michigan
When the ignition switch is turned on, current flows from the battery, through the alternator warning lamp, through the voltage regulator to ground and will be lit.
Is this the case for you? does the light go out when the engine is running?
the two terminals on the plug are the ignition terminal and voltage sensing terminal. if you have the wiring hacked up on the other end, it is possible that the alternator is seeing very low voltage at the sense end and increasing output to compensate. the dash light is connected in series with the ignition terminal and a resistor (so the alternator still works if the light burns out).
Hope that helps.
Is this the case for you? does the light go out when the engine is running?
the two terminals on the plug are the ignition terminal and voltage sensing terminal. if you have the wiring hacked up on the other end, it is possible that the alternator is seeing very low voltage at the sense end and increasing output to compensate. the dash light is connected in series with the ignition terminal and a resistor (so the alternator still works if the light burns out).
Hope that helps.
Melting Slicks
Joined: Jan 2014
Posts: 2,478
Likes: 254
From: Downers Grove Illinois
Thanks for all the help guys, but no one has answered my question about the aftermarket gauge wiring? Being that I have bypassed the wiring to the gauges, has that affected the wiring for the alternator. If im correct,that plug in the alternator controls the gen light, I know that the gen light is not longer being used, BC I no longer have a printed circuit board is that an issue? What about that other wire in the alternator plug?
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
Just the opposite. Without a GEN light to provide resistance the alternator won't charge at all. It seems like the alternator is full fielded, but that requires internal grounding to the alternator case, and IDK how he managed that.
Thread Starter
Racer
Joined: Apr 2015
Posts: 412
Likes: 12
From: Carrollton, Georgia
Okay so I slapped an alternator on there today. Had 14 volts at battery, gauge, and output from alternator. Even when giving it throttle. So seems like the problem is solved, BUT, I don't want another issue, so what is the proper thing to do with the sensing wire?
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
I would put a GEN light back in the dash somewhere. The light should be fed from the battery when the key is on, then matching voltage from the alternator exciter wire when the motor starts. The matching voltage will turn the light off and the resistance of the bulb will signal the alternator to start charging. Others put a resistor in the circuit to simulate the light, but a resistor can't alert you to a charging problem.
Burning Brakes
Joined: Apr 2008
Posts: 1,222
Likes: 93
From: shelbyville West Michigan
there is resistance and loss in the wiring, so if you sense directly at the battery or the output stud of the alternator, you will only put out enough power to keep that part of the circuit at 14.2volts. then where you need most power, which is after that, you have less power because of the loss and the alternator can't see that. so then your headlights dim at idle, or blower isn't full speed, etc...