generator light

[Lolat324]

So, '63 Sr III GT. Generator light won't go off once car starts. Facts-grounds are all good, generator is new (rebuilt), new ignition switch, properly wired!! Battery good, tried another battery-same issue, voltage regulator polarized. Protronics installed. Amp guage shows a positive position after start.. To cold and snowy to drive the car enough to see if the battery is charging. That was the issue last fall. No charge. So we checked things, replaced parts. Still no light off. I'm NO electronics expert..my old man who bot the car new says the gene light will stay on if the drain on the system is high/battery is low as long as the gene can't make more power then needed to run the car..I'll stop talking now. Any ideas, plans of attach? I appreciate it, happy new year to all.

 

[Toyanvil]

The light gets 12 volts from the ignition switch and the Control Box will give it 12 volts when charging and negative when it is not. If it is charging it will have 12 volts on both sides of the light and will cancel each other out and the light will go off. If it is not charging it will have 12 volts from the ignition switch and negative from the Control Box and will be on.

 

[Hillman]

Look at the wiring diagram in the WSM. Make sure the car follows it. If the ammeter is wired correctly, I'd tend to believe it rather than the light.

 

[65sunbeam]

Use a hand held digital voltmeter and check the output of the generator when not running and then when running. You should see nearly 14 volts when running. If no difference, you still have a problem. I recently had to try 3 different new voltage regulators before I found one that worked correctly. Eric

 

[Tom H]

65 Sunbeam's advice is good. But you can do a few things even without a meter

Step 1) With the engine off, and ignition switch OFF turn on the lights and watch the amp gauge. The gauge should go neg when you turn on the lights, because the power for the lights is coming FROM the battery, which will show as neg , or discharge, amps. If not reading Neg, then the gauge is wired in wrong. If it does go neg the gauge is wired correctly and you can trust that it is correctly showing a charge when the car is running.

Step 2) Understand that, unlike an Alternator, a Generator does not put out much charge at idle. Rev the engine to 2000 RPM or higher . Does the light go out? Does the ammeter show MORE charge than at idle? That's good and means you are OK.

Step 3) Connect a test lamp on the battery ( at the battery or at the solenoid connection). You should own a real test lamp- a simple light inside a "screwdriver" handle with a black ground lead. But if not then any spare 12 v tail lamp will do. Start the and let it run for 15-30 seconds. Then watch the test lamp as you turn the car OFF. You should be able to see the test lamp go dimmer when the car is shut OFF. That will show you that the voltage WAS higher when the car was running, indicating that the generator IS working.

These are some useful ways to test your system.

Tom

 

[Lolat324]

Thanks for the replies guys. So my car pretty much failed all three tests..posted by Tom...I do have a tester, a Fluke meter ( I'm no expert) and a very nice wiring diagram. I'll get my two smart buddies and off we go..I'll post back. By the way the car runs great (I carry a spare battery). I went for a Jan 1 New ears day drive today-in SPokane Wa-it was about 26 degrees, top off, ear-flap hat on..Great 20 miler along the Spokane River!

 

[Tom H]

Whoa! You say it failed test #1? The Amp meter did not show neg when you turned in the lights ? That means the ammeter is wired wrong and is not helpful in troubleshooting or understanding your system condition.

 

[Lolat324]

Tom H, yes, first thing to get after..the car had been out of my families hands for decades. My father the original owner never changed the car to negative ground, III's were positive earth I understand. So at issue is when was this done, and was it done correctly, i.e. does this change to negative ground require a change in wiring to the amp meter. Learning curve is steep but less so...will report back. Thanks again

 

[Tom H]

Are you saying the car's polarity was changed at some point to Negative earth? This is new info, not previously stated. I'm not sure what most people do, but it would not be unusual to leave the ammeter wired as original, just be sure to understand it read s"backwards" from original. So if the car is now Neg earth and the ammeter wiring was not changed, then I would expect that when you turn the lights on with the engine not running , the ammeter should show Positive, and that 's OK. The real issue is if turning the lights on with motor not running, the ammeter needle does NOTHING. That would mean it is wired quite wrong, not just reversed. So....Does the anmeter show anything when you turn the lights on - with motor not running?

 

[Lolat324]

Thanks Tom, yes at some time the car was changed to negative earth. I'm searching back through owners.. It makes sense that the amp meter would read backwards..I check it re your recommendation-what happens to the gauge with no motor and turning the lights on..Also could this have affected the fuel gauge, i.e. someone reversed ground, but didn't change the fuel level sending (I'm not sure how it functions in reality)..I'll report back ! Thanks again.

 

[Tom H]

The Temp and Fuel gauges are not polarity sensitive.