vannmike

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?

SH-60B

Sounds like the regulator is no longer regulating. Get it tested.

76C3forme

My "+" terminal was on the verge of melting when the regulator in the alternator crapped out.

Peterbuilt

Sounds like it's time for a new alternator before it totally shorts out.

vannmike

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?

Peterbuilt

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

vannmike

Forgive me, I'm referring to the plug on the alternator. On mine there is a stud for power I believe, then one for ground, and opposite that a plug with 2 wires. I thought that plug was for the regulator?

JimLentz

Are you saying the 2 pin plug isn't connected any more?

MelWff

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.

vannmike

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

vannmike

No it's connected.

augiedoggy

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...

Peterbuilt

Your right, that is a more cost-effective fix, however, vannmike said that insulator is almost melted so he will need that also.

vannmike

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?

gungatim

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.

JimLentz

Without the Gen light or the wiring to simulate that the alternator thinks your voltage is zero and as such outputs the most it can. You can use a resistor wired to the sense line instead of the gen light.

SH-60B

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.

vannmike

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?

SH-60B

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.

gungatim

the sensing wire is what senses the voltage of the entire system in order to tell the alternator how much to put out. you can wire it anywhere you want to sense the voltage, but the ideal way, and the way the factory does it, and why 1-wire alternators are a bad idea, is to wire it after the main wiring distribution bus.

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...