Charging System Advice Needed (1969 Buick Wildcat)

Hello.

I am new to the Forum and am seeking help regarding a charging system issue in my 1969 Buick Wildcat, since i am not very knowledgable about automotive diagnostics and repair.

The GEN light on the dash illuminates ONLY when the vehicle is idling in DRIVE or REVERSE and goes out immediately when the vehicle starts to accelerate. The GEN light does NOT come on at all when the car is put in NEUTRAL or PARK. Any advice on (1) what the problem is and (2) how it can be repaired?

Any assistance with this problem you fellow members can provide would be greatly appreciated.

Don in Colorado

Sounds like the engine idle speed is low. It might have been set too low and you'll need a tachometer to check it. If no one has made any adjustments that you know of it may also be a dirty air filter choking the engine air supply. When was the air cleaner last replaced?

John,

Thanks for responding! I have just recently acquired this vehicle and have not had it long enough to do much to the car. I will certainly check the air cleaner since i do not know when it was last replaced; however, the car idles quite high. At least, it sounds to me as if it is idling high.

I will try to check the air cleaner tomorrow since the forecast is for one more day of nice weather here in Colorado.

Thanks again!

Don

If it is indeed idling quite high then two things, if possible, check the battery fluid level. It may be low. And then consider replacing the alternator and voltage regulator. I recommend sourcing them from your local NAPA. Probably less than $50.00 but if you take yours to them at the point of purchase they can check if you even need to replace them, or if you have to look elsewhere.

Make sure the alternator belt is not slipping. Check voltage at battery with car running with a known accurate volt meter. Should be just over 14 volts. Usually no more than 14.3. No less than 13.8.

Got it. Thank you!

I'll do that. Thanks a bunch!

John,

Got it. Thank you!

Jason,

I'll do that. Thanks a bunch!

Post a few pictures of your car, we have a '68 Wildcat.

Keith

Don't forget about ensuring the battery cable connections are "spotless" on ALL parts of their connection at the battery. I've seen a newer vehicle's charging system check return a 10% drop in output due to "dirty battery terminal connections", on a side terminal battery. I've also had a "decent looking connection" (on a top terminal battery) have a thin layer of insulating corrosion on the inner surfaces of the cable end and battery terminal, which resulted in a "no crank" situation after they heated-up from several start tries.

The "light" will "light" when current flow through the system is "negative" rather than "charging". The intensity of the light will typically indicate the size of the "reverse flow" situation.

From your description, I suspect the idle speed is a little slower than it needs to be (when under load of being in gear). An easy-for-now fix would be to slightly increase the idle speed, possibly 1/4 turn of the idle speed screw. THEN, when the opportunity might exist, start with the ignition points replacement/adjustment (as this also influences ultimate ignition timing), then when the points are adjusted at approx. 30 degrees of dwell, check the base idle ignition timing with a timing light, then adjust/readjust/tweak the base idle speed at the carburetor . . . in that order of progression.

It also might be that the alternator is getting some age on it, with slightly decreased output at idle speeds (output increases, up to about 2000rpm, with increasing engine speed), it might be a little weak. Might be a belt issue, but also clean the battery cable terminals to ensure that connection is "clean and tight". DO NOT tighten the battery terminal bolts, on side terminal batteries, past a "good, snug" point as overtightening can crack the pad they screw into, which can result in battery acid leaks into the cable and to surrounding underhood areas.

One somewhat overlooked, but still important, item is that the charging system circuit goes through the wiring harness bulkhead connector on the firewall, below the power brake booster. As advancing age, those terminals' factory protective coating can become a little compromised, which is another "resistance point" for the electrical power production system to overcome, which can result in functionally-decreased alternator output further "down circuit" from the alternator itself. Use this as a "last resort" sort of thing, though, but something to also be aware of.

If it has an external voltage regulator, there are some internal points in it to regulate the alternator's output. They, like ignition points, can become compromised with age and use, but usually less prevalent an issue then ignition points. Start with the alternator, though, when diagnosis has begun, then progress through the charging system (after the battery terminal condition has been investigated and cleaned.

Please us updated as to your progress.

Enjoy!

NTX5467

Dear NTX,

Thank you very much for the thorough diagnosis! Once i get back on my feet--my back went out yesterday--i will implement your suggestions.

Have a great week.

Don

I hope you have a speedy and lasting recovery, for your back and your Buick!

NTX5467

Dear NTX,

Unfortunately, my recuperation has been slower than anticipated or desired. Thank you for your well wishes!