Generator Warning Light - always On (red)

Stupid question: How’s your belt?

I only ask because the only time my Gen/alt light has come on is when the belt popped off the pulley on my ‘64 Bug.

what does Dave say to the red light..or is it "Daves not here"(have to be old to remember this):}

Yeah - Make sure the pulleys are not slipping on the belt.

There are two wires on top of the alternator (ne generator).  A big one at 8 - 10 gauge and a smaller one like a 16 gauge.  Remove both (one at a time) and clean up the contacts so the mating surfaces are shiny.

Get under the car at the rear on the passenger side and find the starter/solenoid on the passenger side of the transaxle bell housing.  One at a time, remove the big battery cable and the other end of the big wire on your alternator and clean up the terminals on both of those.  Be careful that you don't touch either to ground while cleaning them - There's enough potential in the battery to vaporize a tool.

After that and if that doesn't cure it, the only thing I can think of is the alternator isn't grounding to the pedestal it sits on and/or the ground strap between the engine and chassis ground needs to be cleaned up.

If THOSE don't cure it, then the alternator diodes have opened up and the alternator needs to be swapped out or rebuilt.

@Gordon Nichols posted:

If THOSE don't cure it, then the alternator diodes have opened up and the alternator needs to be swapped out or rebuilt.

In related news: I went by the last of the old-school auto electric shops in my town that rebuilt my starter and alternator two years ago and they’ve closed up shop.

I guess it’s remans from now on.

@Gordon Nichols posted:

There are two wires on top of the alternator (ne generator).  A big one at 8 - 10 gauge and a smaller one like a 16 gauge.  Remove both (one at a time) and clean up the contacts so the mating surfaces are shiny.

Get under the car at the rear on the passenger side and find the starter/solenoid on the passenger side of the transaxle bell housing.  One at a time, remove the big battery cable and the other end of the big wire on your alternator and clean up the terminals on both of those.  Be careful that you don't touch either to ground while cleaning them - There's enough potential in the battery to vaporize a tool.

After that and if that doesn't cure it, the only thing I can think of is the alternator isn't grounding to the pedestal it sits on and/or the ground strap between the engine and chassis ground needs to be cleaned up.

If THOSE don't cure it, then the alternator diodes have opened up and the alternator needs to be swapped out or rebuilt.

PLEASE PLEASE disconnect the battery negative terminal before you play with any of the wiring. There is a lot of current and damage potential if any of your "hot" wires touch ground when you're working.

And I've NEVER seen any car charge at 14v AT IDLE. You might get 12.8 to 13.2 or so, but the voltage should go up to at least 13.5 when you rev it up over 1500-1800 rpm.

the old school generator rebuild guys are gone,,had a 70 Cat forklift, Perkins diesel..generator or starter going bad always, this old guy knew/fix anything,,hes long gone

@dlearl476

Dave’s right - with the way things are built these days, the labor $$ needed to rebuild things like alternators makes the effort not economically viable so many of those old auto/truck electrical shops are gone.  It’s cheaper to just buy a new gizmo.  

And @DannyP - “Real Men” don’t disconnect the ground cable.”

Of course, “Real Men” also have lost a couple of fingers, have a lot of scars and have probably blown more than a few things up.

Thanks for the reminder!  (And remember to disconnect the Ground cable at the battery before you start!)

According to my guy, the thing that did them in was parts availability. 20 years ago, you could look in a Bosch catalogue and find parts for any starter, generator, distributor, horn, or headlight they made. Going back to the 50’s. Nowadays, you look in their website and it’s 100% PR and marketing.

The business model these days is wholesalers collecting cores, shipping them off to remanufacturing plant to be resold in O’PepZone stores and Rock Auto.

@dlearl476 posted:

Stupid question: How’s your belt?

I only ask because the only time my Gen/alt light has come on is when the belt popped off the pulley on my ‘64 Bug.

Thanks...Belt is on good....

@barncobob posted:

what does Dave say to the red light..or is it "Daves not here"(have to be old to remember this):}

@barncobob you got me on that one! and I'm near 70...???? I haven't heard it or can't remember but that is happening a lot lately...haha

@Gordon Nichols posted:

Yeah - Make sure the pulleys are not slipping on the belt.

There are two wires on top of the alternator (ne generator).  A big one at 8 - 10 gauge and a smaller one like a 16 gauge.  Remove both (one at a time) and clean up the contacts so the mating surfaces are shiny.

Get under the car at the rear on the passenger side and find the starter/solenoid on the passenger side of the transaxle bell housing.  One at a time, remove the big battery cable and the other end of the big wire on your alternator and clean up the terminals on both of those.  Be careful that you don't touch either to ground while cleaning them - There's enough potential in the battery to vaporize a tool.

After that and if that doesn't cure it, the only thing I can think of is the alternator isn't grounding to the pedestal it sits on and/or the ground strap between the engine and chassis ground needs to be cleaned up.

If THOSE don't cure it, then the alternator diodes have opened up and the alternator needs to be swapped out or rebuilt.

Thanks for the suggestion will do that tomorrow and see if it makes a difference....

@dlearl476 posted:

In related news: I went by the last of the old-school auto electric shops in my town that rebuilt my starter and alternator two years ago and they’ve closed up shop.

I guess it’s remans from now on.

Yes...nothing is built to last anymore....we are in a "if its broke, buy a new one world" And refrigerators that you buy now a days,  that are all made out of plastic parts inside, if a circuit board go's on one  them you can't buy a replacement board after just only ONE year in service....to bad big boy....buy another one! My parents had a Westinghouse Fridge for 20 years.....times have changed and not for the better. Sorry went off the rails there....

@DannyP posted:

PLEASE PLEASE disconnect the battery negative terminal before you play with any of the wiring. There is a lot of current and damage potential if any of your "hot" wires touch ground when you're working.

And I've NEVER seen any car charge at 14v AT IDLE. You might get 12.8 to 13.2 or so, but the voltage should go up to at least 13.5 when you rev it up over 1500-1800 rpm.

If I disconnect the wires on the generator and start the car would it be a good test to put a VOM on each terminal to see what the voltage output would be  on each terminal to ground?

@Gordon Nichols posted:

@dlearl476

Dave’s right - with the way things are built these days, the labor $$ needed to rebuild things like alternators makes the effort not economically viable so many of those old auto/truck electrical shops are gone.  It’s cheaper to just buy a new gizmo.  

And @DannyP - “Real Men” don’t disconnect the ground cable.”

Of course, “Real Men” also have lost a couple of fingers, have a lot of scars and have probably blown more than a few things up.

Thanks for the reminder!  (And remember to disconnect the Ground cable at the battery before you start!)

Great thanks for the reminder, you can never be too cautious!......

@Larry Scislowicz posted:

@barncobob you got me on that one! and I'm near 70...???? I haven't heard it or can't remember but that is happening a lot lately...haha

believe it wasa Cheech Chong movie were they were HI sure U could find it on youtube if ur really curious..

I remember it being on a Cheech and Chong comedy LP. The one with "Basketball Jones", "Sister Mary Elephant". The one we had was a greatest hits disc, came out in 1981.

"Dave" was on their first album(self titled) in 1971according to Wikipedia.

Late nights at my friend's NJ WV shop Anthony and I would play the Cheech and Chong 8 track over and over and we recited the entire album word for word as the beers went down...   "The Pope" is priceless  "..an da tird"...he gotta have a'  big a'   its ...boom da boomdaboom

Red light on my car is oil pressure. Green light is alternator. Your car may be different. You can drive a while with a bad generator or alternator. Not so far with low oil pressure. I'd want to know for sure which is which. Perhaps you do.

Hi Jim.....RED on my car is the Alternator.

The Vintage Spyder I'm working on has red for alternator/generator and green for oil also. As long as you know which is which it doesn't matter.

Easy to figure out. Turn key to on, then remove wire from oil pressure switch. The light that goes out is oil.

I've always used the "GO" method, left to right. Generator-Oil. And generator/alternator to my mind should be green, and oil should be RED for STOP NOW.

Sounds good...thanks!

On my Beck with early Brazilian VDO repros, both the oil and gen/alt light are red. Kind of like this one from a post by a “former member” from 2010,* only I don’t have numeric scale or logos. And my left light is yellow, as indicated by early 356 manuals, should either be a parking light or parking brake indicator.

My tach also has two red lights at the bottom (which aren’t wired to anything) flanking my single, double arrow, indicator light.

*According to the thread, these ones with the fuel light were custom made by PAS.

@Jim Gilbert - Madison, Mississippi posted:

Red light on my car is oil pressure. Green light is alternator.

@DannyP posted:

The Vintage Spyder I'm working on has red for alternator/generator and green for oil also. As long as you know which is which it doesn't matter.

I just looked it up on Dan Whites 356 Literature page hoping to find my multi gauge  Early 356 gauges were (L) Alt/Gen = Red, (R) Oil pressure = green. So Danny, it looks like that vintage has a correct 356 gauge.
https://derwhites356literature...ittleKnownFacts.html

My car is a vintage CMC where the lights are separately mounted into the dash by themselves (see pic attached) the Generator Warning light is the one to the right of the clock.. ....Thanks

Also, the new repros have two red lights, but they’re reversed from my repros and early 356 gauges.

Watt the Frick, im really confused now,,U get 2 red lights and ur day is over..

Here’s a thought? Do the alternators with the built in regulators default to ignition lights when they go bad? Or do they just overcook your battery?

Either way, I think a multimeter on your battery terminals and some quick revs would tell you if your alternator was working. If it is, it’s a wiring issue somewhere.

Like Danny said, should read between >12V-13.5/13.7, depending on revs. If it’s not (reading simple battery voltage) or <13.75, somethings wrong with it.

ps: as someone who just about arc welded a nut driver to his roll bar while tightening his + lead, I wouldn’t get anywhere near the connections of the Gen or starter with the car running. (There’s a reason there’s rubber caps on them)

Unless something is wrong, you should get the same reading on the battery terminals that you get in the generator leads.

Good thought....I'll stick with monitoring from the battery ..the last test I did I was by myself and the engine way just on idle, need to have someone rev it up and watch the VOM and see what it reads then.......not into arch welding myself....more info to come!

I see that you're beginning to understand why we welcome people to this group by saying:

"Welcome to the Madness!"

@Larry Scislowicz, I recently replaced an alternator that had at least one blown diode as Gordon mentioned above. It's an easy test with your Volt Ohm meter. Set the meter to a lower range AC setting (I think I used 20V AC). Just put your test leads between +12V and ground (at the battery or at the alternator output). If you see any AC voltage showing up, I think I saw around 5V AC, then you've got a bad diode or more.

I replaced the alternator and everything's back to normal.

Thanks Michael that is  a great test to do.....will try it today.

@Jim Gilbert - Madison, Mississippi posted:

Red light on my car is oil pressure. Green light is alternator.

That light ain't oil pressure, you knuckle heads, it's oil temp. I'm glad I realized that before ya'll had a chance to point that out:<

My car is JPS. So it's is correctly wired. Right?

Anyway; a while back I replaced the alternator since it wasn't alternating. The replacement didn't alternate either. Spent considerable time trying to diagnose the problem since it was unlikely that two new alternators were bad. Come to find out the alternator light was the issue. Alternators won't alternate unless the light is working. I was not aware of this at the time.

Having said all that and subsequent to this discussion; I have contemplated which light arrangement offers the best benefit. Original thinking was that the most critical was oil temp. The loss of the fan belt will show up quickly in rise of engine temperature.

In flying, a constant scan of the instrument panel is necessary to staying alive. Not so much in a car. I suspect most of us look occasionally, not frequently, unless some obvious problem presents itself.

So as not to confuse myself, even thought the consensus is that my lights are in the wrong hole, I'm sticking with the RED oil temp.

Just saying...

Sounds like you have a bad alternator, however, I can also see in your photo that you do not have the ground wire on the alternator (straight slotted screw by itself about center of the alternator).  It should ground both through the fan shroud and the generator base stand, but I also see a lot of chrome in there and chrome is a cr@p conductor, so personally I'd jumper a ground to it and see if that does the trick, if not order a new one.

Not to mince words, and by your description it sounds like you understand what you have, but FYI it is an alternator not a generator.  I only mention this because in the VW world if you were to call and order a generator, you'd get the early version generator requiring an external regulator and not the Bosch alternator you have.  Again, only mentioning this so you don't get the wrong part if ordered over the phone from somewhere is all.

As for lights, I prefer red for both alt and oil, however vintage Porsche (esp 911) used green for low oil pressure indicator regularly which is why you see it done in the repros.  I just don't equate green to warning, which is why I personally don't like it, whereas red (to me) says PAY ATTENTION.

@Jim Gilbert - Madison, Mississippi posted:

That light ain't oil pressure, you knuckle heads, it's oil temp. I'm glad I realized that before ya'll had a chance to point that out:<

My car is JPS. So it's is correctly wired. Right?

Anyway; a while back I replaced the alternator since it wasn't alternating. The replacement didn't alternate either. Spent considerable time trying to diagnose the problem since it was unlikely that two new alternators were bad. Come to find out the alternator light was the issue. Alternators won't alternate unless the light is working. I was not aware of this at the time.

Having said all that and subsequent to this discussion; I have contemplated which light arrangement offers the best benefit. Original thinking was that the most critical was oil temp. The loss of the fan belt will show up quickly in rise of engine temperature.

In flying, a constant scan of the instrument panel is necessary to staying alive. Not so much in a car. I suspect most of us look occasionally, not frequently, unless some obvious problem presents itself.

So as not to confuse myself, even thought the consensus is that my lights are in the wrong hole, I'm sticking with the RED oil temp.

Just saying...

Thanks Jim.....since it is your car you can do as you please and no one will "MANDATE" your color choices....but I agree that a RED light will get get your attention!

@chines1 posted:

Sounds like you have a bad alternator, however, I can also see in your photo that you do not have the ground wire on the alternator (straight slotted screw by itself about center of the alternator).  It should ground both through the fan shroud and the generator base stand, but I also see a lot of chrome in there and chrome is a cr@p conductor, so personally I'd jumper a ground to it and see if that does the trick, if not order a new one.

Not to mince words, and by your description it sounds like you understand what you have, but FYI it is an alternator not a generator.  I only mention this because in the VW world if you were to call and order a generator, you'd get the early version generator requiring an external regulator and not the Bosch alternator you have.  Again, only mentioning this so you don't get the wrong part if ordered over the phone from somewhere is all.

As for lights, I prefer red for both alt and oil, however vintage Porsche (esp 911) used green for low oil pressure indicator regularly which is why you see it done in the repros.  I just don't equate green to warning, which is why I personally don't like it, whereas red (to me) says PAY ATTENTION.

Agreed!

Oil temp light?  How does that work?  or are you kidding?  Its too early and Ive had too little coffee for sarcasm just yet.  ;-)

I'm working on the broken plastic behind the bumper cover of my Z4 this morning. Mississippi roads are not forgiving to low plastic chins.

Alright, alright! Yes, it's oil pressure light!

Duh...Logic is clouded by frustration!

UPDATE-UPDATE - Tested across the battery 12.6V (engine NOT running), 12.7V  (engine at Idle), 13.6V (engine at fast idle)....WARNING LIGHT OUT.

OK...went from a steady Warning light ON, to now it appears to be working correctly.

So now it has gone to the category of "SQUIRELLY" and now in "Observation Mode"...will report in later and see how it go's.....

Larry, speaking as a retired sound guy with 30 years experience, “intermittent” (and its service department equivalent: “unable to duplicate customer complaint”) are the most frustrating problems to diagnose and fix.

The good news? It’s probably just a faulty connection somewhere. For you, and everyone, I can highly recommend this little kit from Amazon.

DeoxIT Caig New Audio/Video Survival Kit - SK-AV35 https://www.amazon.com/dp/B07B...VQ2KHZEB2SSAQYSA0TG1

Has a little bit of everything to keep your electrical connections connecting.

I’d advise disconnecting your battery and undoing all your connections and treating them. Under your dash as well. (Do the connectors one at a time so you don’t mix them up)

If you prefer, you can simply get deOxit Gold with a brush applicator, pin oiler, or aerosol. It’s expensive, but a little bit goes a loooong way.