1962 Cadillac Generator Tell Tale Light Staying On

[Matt Innocenzi]

Hello all - the generator tell tale light is staying on in my '62 Fleetwood.  The generator was rebuilt in 2010 with less than 1,000 miles on it.  Although the light has been on, the car has been driven nearly 2 hours and 100 miles with no strain on the electrical system and no problem starting it. 

I tried changing batteries and put a brand new battery in - no difference.  I tried polarizing the generator when I changed batteries by jumping battery and generator terminals on the voltage regulator - no difference.  I checked the in-line fuse on the tell tale wire - its good. 

I would suspect the light staying on is instrumentation because of how long the car is able to run without a problem.  What could be causing it to stay on?  I also noticed when i turn the key counterclockwise to Accessory, it does not come on - just when I turn to "on" and start.

Any suggestions?

Matt

[62 driver]

Can you do a volt meter test and report the results?

[Matt Innocenzi]

Absolutely - but not sure where to take voltage.  Is there a procedure for this outlined in the Shop Manual?

[Commodore]

One test you can do is take the voltmeter and measure the voltage across the battery with the engine off and note the reading. Start the car and run the engine at about 2000 RPM and measure the voltage across the battery and note the reading. The second reading should be higher then the first. If it is not then it's not charging. The fact that the generator had been recently rebuild doesn't mean anything. The generator could fail at anytime due to something like a broken brush spring.

[62 driver]

1962 Cadillac shop manual

Electrical System  page 12-19.     "Charging System"

[dplotkin]

I would suspect the light staying on is instrumentation because of how long the car is able to run without a problem.  What could be causing it to stay on?  I also noticed when i turn the key counterclockwise to Accessory, it does not come on - just when I turn to "on" and start.
Any suggestions?Matt

I assume you have a generator and not an alternator, which some late 1962 GM cars with A/C did have.
The dash lamp comes on with ignition on only. Your lamp is on because more battery current is leaving the battery than is being replaced by the charging system. A healthy battery can run a cars ignition system for 100 miles or more as long as lights and accessories are not also in use.

As already suggested by others you must put a voltmeter across the battery with the engine running at or near 2,000 RPM. A properly functioning system will show between 13.8 & 14.5 V. Anything less is suspect. With the engine off the battery reading should be about 12.6 V IF the battery is fully charged.

If you are reasonably sure your generator (or alternator) is or should be OK, than the regulator is the next suspect. If you can swap it out with a known-to-be-good one, do that as I suspect that is where your problem is.

Dan

[Walter Youshock]

Check the voltage regulator.  There is a process for cleaning the regulator contacts and adjusting the regulator.  If it's not properly set or the contacts are burned, you can rebuild the generator all you want and the light will be on...  I went through this on the '57.  My car was actually overcharging and the battery would purge.  Once I adjusted the regulator, the light went off and the trouble went away.

The regulator is the "brain" of your electrical system.

[Scot Minesinger]

Matt,

Yes, if alternator is charging at 2,000 rpm and you have a reading of like 14volts that would also verify that the regulator could be working.  I have had trouble with regulators too.  You should have a spare regulator.  If your regulator is not adjustable, and you can swap them out to see if it changes things.

I sure hope you are bringing that 62 Fleetwood to Sully this Sunday!  It is Father's day so you get to do that even with young children.  See you there,

Scot

[6262]

I assume you have a generator and not an alternator, which some late 1962 GM cars with A/C did have.

Hello Dan,

I have a June '62 car with A/C. It had a generator that was replaced by an alternator. I don't want to go back to the generator, but I'm rather unhappy with the incorrect setup. Therefore some background information about your statement and a source would be great. I assume you refer to '63 alternators in late '62 models?!

[dplotkin]

Chevrolet & Pontiac used alternators in late 62 production (I own a Pontiac with a factory alternator & a friend has a 62 Impala with one as well). I'm not sure Cadillac did as I've never seen one, but its possible.

Regardless, on a hobby car a generator is just fine and would be my preference if that was originally what your car had.

Since this sounds like a "conversion" from a generator to an alternator, you need to stop & trace out the wiring to see what the fellow who performed this conversion actually did. First, put the meter across the battery while running & let's see if in fact it is charging and report back.

Dan

[SixDucks]

Hello Matt,
I believe you need to polarize your generator. The steps are outlined in your chassis manual. Others may chime in on how to perform this. It only takes a second. I'll post back with the exact steps should you need assistance.
Hope this helps.
Terry

[Matt Innocenzi]

Hello all:

I took some voltage readings.  With the car off and no accessories on, I get 11.95V on the battery.  With the engine running at 2,000 rpm, the reading dropped to 11.3V.  It sounds like indeed the battery is not being charged.

I polarized the generator, so unfortunately, that is not the problem.

It now appears to be either a mal-adjusted voltage regulator or generator.  Will keep everyone posted and please let me know if any other ideas.

Matt

[Jeff Rosansky CLC #28373]

Yes, it is not charging.  Go ahead and put the battery on a charger for now so that you don't end up hurting it. 
Before you go to extremes, check every wire and every connection to be sure all is tight and not corroded.  Some of those regulator wires are not that big but they make all the difference in the world.

You can bypass the regulator to see what you get (should be in the manual).  If not, probably easiest to just take it off and take it to your local Autozone and have them test it. 
Jeff

[Julien Abrahams]

I had a similar problem on my '67. The battery was actually being overcharged (I got around 17 volts), and I noticed this by the rapid incline of the temperature gage. On the highway, it would go all the way up, and once I took an exit, it would immediately drop. Took my generator and regulator to a local shop that rebuilds starter motors, generators and alternators, where both were checked, and it turned out to be a maladjusted regulator.

[Matt Innocenzi]

Problem solved - all of my testing was suggesting the generator.  I removed it, took it to the generator shop and they confirmed it was not charging. 

So, before you dismiss  your tell tale because your generator was just rebuilt 2 years ago, it really can happen!  I learn something new all the time.

Thanks to all of you for offering the help and insight!

Matt

[Walter Youshock]

Years back when I first got the '57, my dad took me to one of his old buddy's garage who specialized in charging systems.  He rebuilt the generator and I had a new regulator I installed out of the box.  He said you HAVE to adjust the regulator to the generator.  They were test adjusted but not for the specific car.  Most people don't do it but that stuck in my brain.

So, the original Delco is adjusted and on the car now and I keep an adjusted spare under the front seat.