Good ol' gen light on 64 impala - Impala Tech
Electrical & Wiring Troubleshooting electrical problems

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post #1 of 10 (permalink) Old 06-28-2011, 09:55 AM Thread Starter
Join Date: Jun 2009
Location: Melbourne, FL
Posts: 37
Good ol' gen light on 64 impala

Ok, you guys are always so helpful on here! I have run into yet another problem, lol... go figure. My GEN light is staying on even when the car is OFF and key is in OFF position. It is causing my battery to die and i am having to charge it when i want to drive the car. I have looked all over this site and others and have found a few things but thought perhaps you guys could narrow it down. The only things i found on here were when the brake was applied, or when the car was running. This is happening when my car is OFF. If this is a repeat question i apologize, but would appreciate the help. I recently replaced the ignition lock/cylinder so that would match all of the new locks on my car and also because you could start my car without the key.

Thanks again for all of your help.
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post #2 of 10 (permalink) Old 06-28-2011, 03:49 PM
Join Date: Nov 2010
Location: Mpls,MN
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I have the same problem on a 1963 Impala.
New battery
New ignition switch
New neutral safety switch
New Relay
New Voltage Regulator

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post #3 of 10 (permalink) Old 06-29-2011, 12:14 AM
Join Date: Jan 2006
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Well easiest solution is a disconnect switch at the battery. As soon as you turn it off get out in whatever weather you find yourself, raise the hood and flip the switch. No more problem.

What is the problem. You have a short in one of your car's wires (don't ask which one because I don't know which one it is.) I suspect it is in the charging circuit and the first thing I would check is the voltage regulator if you have a DN style alternator, or the alternator's internal diode pack if an early SI style alternator.

Other suspects are the ignition wiring or the ignition switch. The brake switch or the Hi-Low dimmer switch on your floor boards, as both have a lot of power going through them, or the horn button or turn signal switch in side the steering column. It could be corrosion in the bulkhead connector that forms the back of the fuse block. Or some earlier idiot may have some non-factory wire plugged into the fuse block that powers some accessory (like a non-stock radio) that is drawing from the BAT terminal.

There are as many possibilities as there are wires in your car (and there are more in your car than you think there are). This is why 95% of all electrical problems are fixed by replacing the entire wiring harness. This is because it is too labor intensive (unless you are working for Jay Leno on one of his rare cars) to attempt to diagnose an electrical problem going over and testing every circuit for ground, continuity and resistance, as well as measuring the amperage it conducts to eliminate it as the cause of your problem.

You can buy an universal kit from Painless or American Wire and save money if you are good with electronic circuits; or a direct fit original OEM replacement reproduced part that costs a lot more from one of the repop houses, and just replace what you have now.

Big Dave
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post #4 of 10 (permalink) Old 06-29-2011, 01:34 AM
Join Date: Sep 2010
Location: Saskatoon
Posts: 45
I have the same problem in my 64, my gen light stays on with they key off. Soon as the engine is started though it comes off, then on when car is shut off. I replaced ignition switch, lights, dimmer and wiper. Now I just do like Big Dave says, put a disconect switch and your done.
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post #5 of 10 (permalink) Old 06-29-2011, 07:30 AM
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Gen light

I would get out my trusty assembly manual or service manual and trace first the generator light wiring and go from there. These problems may be as easy as a faulty ground.



1966 Impala SS

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post #6 of 10 (permalink) Old 06-29-2011, 09:21 AM
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Try unplugging the connector to the voltage regulator and see if it goes out. If so, replace the regulator. I would recommend a solid state regulator. I went through 3 standard replacements, none of which worked right, then I got this one

and it works great.

1964 Impala 4 door sedan

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post #7 of 10 (permalink) Old 05-05-2017, 01:05 PM
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I got a related question. Please excuse me if sth is completely obvious, but I just got my very first classic car.
It's a 64 Impala SS 2dr. It looks like it has been converted to an alternator (SI10 from what I can tell) with a ONE-WIRE system / layout.
Is this the reason my GEN light stays on after engine start?? I read some stuff at madelectrical, pointing out the advantages of a 3-wire layout. Easy to do?
Would you recommend to convert my layout to a 3-wire? Or is there anything else I could do to get the light working?

The old voltage regulator still sits there with the wiring harness connector plugged in. So I did the resistance wire check according shop manual, but it was negative.
But I guess the old regulator is not being used by system at all right? The wires just disappear in a harness, not able to trace them.
I read sth about grounding???

You see I'm not too much into electrics, so...
Any help is appreciated! And sorry if this topic has been discussed already. I couldnt find anything that helps a complete beginner...
You need any other information about the wiring? I could find a wiring sketch in the trunk. Find it attached.
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post #8 of 10 (permalink) Old 05-05-2017, 04:17 PM
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Two of the four wires going to the voltage regulator need to be cut and sliced together. The other two are capped off. The only difference between the three wire set up and a one wire is that the three wire begins charging as soon as you tun on the ignition. With only the one wire you have to wait until the car spins up to about 2,000 RPM before the system begins charging (it is self exciting but requires copper coils spinning inside a steel core to generate enough power to excite the windings.)

By the was one wire alternator is usually a CS series not an SI, though even a newer series is used on new car and trucks now.

Big Dave
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post #9 of 10 (permalink) Old 05-05-2017, 05:19 PM
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Big Dave, thanks for your answer!!!

But what about my GEN light? How do I wire it correctly in a one wire system? It keeps lighting all the time...
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post #10 of 10 (permalink) Old 05-05-2017, 06:03 PM
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You can't use a gen light with a one wire system. One more benefit of the three wire, as you have read on the madelectrical site (good resource, btw).

Two doors, four doors, wagons, and ragtops.
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1964 impala, gen light, generator light

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