When should the GEN light be on?
 

I've got most of my 68 GTO electrical system hooked up, car starts with key, everything works ... except I'm not ever getting a GEN light on ... under what circumstances should I see it lit?

Right now in the ACC position, no GEN light, in the "Start" position, right before the point the starter engages I get the OIL light and TEMP light on, but no GEN light. With key in just the IGN position I get only OIL light. Bulb is good, tested it. Regulator is OEM original, looked clean and in good working order inside ... but who knows. Printed circuit is new. Engine harness is new, dash harness is original but in great shape. Ignition switch is aftermarket ... with the OEM ignition switch I was getting a flicker out of it when I switched between IGN and ACC, not seeing that now.

I assumed all warning lights should come on when the switch is just past IGN but not starting the engine yet.

I have not tested the charging system yet. Has an original Alternator with new diodes I put in.

Also .. is there any way to test the GEN light, engine off, to attempt to make sure at least the wiring/PCB are good and bypassing other potential problems like Regulator or Ignition switch?

Thanks

Light should be dim when in the accessory position, bright when in run (engine off)
Possibly a bad regulator.

From the diagnosis manual

Thank you again ... your patience with my hesitancy to open the diagnostics manual that is sitting right on my workbench is astounding :)

I thought you had one lol.

After the first step of the diagnostics (jumping pin 4 to ground). Light now works, hmmm, a chance it could have been poor contact on that terminal, although they were thoroughly cleaned and have a new harness.
Wonder if the jump freed up something in the regulator ... I did clean the contacts on the regulator when I had it open ... perhaps some tiny bit of something lodged somewhere.

Now I get a GEN light at about 90% brightness with the key in the run position (engine not running), goes to 100% just before engaging starter, I get no light in the ACC position.

By the way ... how good are the solid state regulators being sold now? Do they more narrowly control voltage like modern vehicles (13.5v - 14.6v I think) ? I know modern charging systems sense battery voltage and adjust accordingly like a "smart" charger etc.

I've always had a very low tolerance for a poorly performing electrical system ... so I'm thinking I will end up with a solid state regulator. Want to keep the original looking alternator though.

voltage Regulator
 

I had a problem. When my 65 GTO would idle the interior lights would flicker. Changed my regulator to a TRANSPO D9212S transistor one. The flickering stopped and my original cover fit. making it look right. Bob.

The corvette vendors sell a kit to covert your VR to solid state. That way you can keep your original VR frame and cover. I’ve also had good luck with the Wells electronic regular. Drill out the retaining rivets and you can use the Delco cover.

Conversion Kit

Ordered a Wells ... wonder if they are made in the US, it's a US based company that does have production capacity in the US.

Gotta be more reliable than electromechanical units.

By the way, ordered a Wells WVE 1V1038 from Rock Auto ... it's made in the USA. I was every surprised ... so if you need a regulator .. that would be the company to support.

Installed the new regulator. I have all lights in the start position, dim light in the Run position, nothing in the ACC position.
I noticed the diagnostic manual only specifies the light being on in the Run with the engine off.

Probably going to have to wait till the next time I start it to sort this one out.

I'm remembering that would have been correct dataway.

No red light while smooching with radio on!

I remember the light being dim in the accessory position and bright in the run. This is also verified in the 68 owners manual, pg 18, under the Ammeter heading.

There are two wires from the ignition switch Accessory terminal.
The brown wire feeds the Acc fuses.
Brown with white tracer goes to terminal H of the interior side fuse block. A second brown wire goes from terminal H to the gauge panel for the Gen indicator light.
My guess is that the brown/white wire is resistive to provide a dim indicator.

The Gen light goes bright when powered by the voltage regulator contacts through terminal H of the fuse block

I'll have crawl under there and see if anything is amiss. I wonder if a solid state regulator alters the behavior in any way.

I know with an LED bulb in place all it will do is come on in the start position. With a normal bulb in place it glows dim in the Run position and lights in the start position.

So far I've gotten nothing in the ACC position no matter what I do. I'll check the schematic for clues.

Do you still have the LED for the GEN indicator? Try swapping it out with an incandescent. Something I read some time ago that LEDs don't have the required resistance for the charging system to work properly when used for the charge indicator light.

I've been testing it with the incandescent. Currently with the new SS regulator and LED installed it will only light in the start position. With the OEM regulator it would light in the start position, and ign position with the LED.

With incandescent it lights in start position, glows dimly in IGN position.

The engine was not running in any of these tests.

I'm going to have to see what diagnostics I can do to the alternator without the engine running ... I did replace the diodes and rebuilt it myself. I checked the diodes after installation (forget what the process was) and everything looked good. Although I'm not sure what if any effect the alternator has on the Gen light with the engine not running.

Going to try a different battery too, right now I'm testing it with a little motorcycle battery hooked up. Voltage in the area of 12.6.

That the light shines bright in the 'Start' position doesn't sound right. Its been a few years but I don't recall the GEN light being on in the start position.

Do you have the original starting switch? What happens if the old one is used?

I'm talking about the position just before it engages the starter where it does the idiot light test ... turns on all the lights to basically check the bulbs. Ignition switch is currently a repop. Haven't tried installing the original again, it was pretty tired.

Last night I turned out the shop lights and tested it. With engine off it glows dim in both Run position and ACC position.