My Generator light just began blinking intermittently on my 74.
Any thoughts on common reasons for this to happen!?
Thanks
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Generally voltage regulator or alternator. Could be loose belt too.
I had to have my alternator rebuilt and now the light does nothing. I was told that the power for the light, when the engine is not running, is internal to the alternator.
Can I check alternator/battery with this simple device!?
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I get readings of 16.8-19 after idling 20 min with car on
16,8 is too high a voltage. Your harbor freight meter might not be accurate. It is safe to assume you have another vehicle , test that one. 14.7 at the battery would be OK. Then you can determine if your meter is off or the Pantera alt is over charging.
You did not say if you are still running the stock alt or you have up graded.
A loose connection or high resistance in the alt / reg ground circuit can cause strange voltages. Start there rather than throwing parts / money at the problem.
Most major auto parts stores can test the alt if removed from the car. My gut feeling would be more likely around the regulator. The first regulators were mechanical , the later solid state should fit without rewiring. I have no idea when Ford made the switch to solid state.
I would expect a bad alternator to under charge rather than over.
If the alternator was trully bad consider a late model internal regulator in the 100 amp range. That does open the can of worms of up grade the amp meter in the center sub dash. The amp meter handles all the current in the system and can be a fire hazard. There should be plenty of information on this forum on that subject.
Hi David
Tested another pantera at the battery without starting car got roughly same voltage around 17 or so
Think it's my meter that off?
My ammeter gauge needle bouncing wildly but I dont know if that's related?
That should not happen. I have no idea. Do not ground out the amp gauge as that will destroy it, $200.00.
The posts should be protected.
Dick Ruzzin
I have the same harbor freight meter as a part of my survival tool kit. Mine reads close to a commercial Fluke meter. I got lucky.
The Pantera amp meter is known to bounce around alot. That is also covered in the threads of the forum.
I changed gauges to Auto Meter and the amp meter is now a expanded scale volt meter. I feel the information is more relavant.
Still would not hurt to make sure connections are clean and secure.
The front compartment has a stud welded to the chassis for a ground connection. The engine has a ground strap at the rear of the transaxle. The voltage regulator (stock one) is in the right rear wheel well , could get wet and corroded connections. There is also a common ground stud under the dash that can be problematic. I would think the under the dash ground would affect things in the cabin and dash mostly.
Panteras are known to have electrical problems. This forum is a wealth of great information.
Without starting the engine and no load I would expect more like 11.5 to 12 volt with a well charged battery. Starting the engine at curb idle the voltage should climb to 13.5 to 14.7 volt.
Harbor Freight also has a automotive test device that has a series of leds that show approx. voltage. A whole $4.49.
WarrenVictor,
as for your DMM displaying higher than expected, I wonder if that "battery" icon on the left is an indication the battery in the meter is low and needs to be replaced?
I was looking for instructions for that meter and found this on how to "calibrate"
Excellent observation!!!!!!!!!!!!!!!!
Thank you all for your great input!
I changed battery in meter and made a difference.
I get 12.7V at battery and 14.7-15.3V (reading fluctuates) while engine runs!
My other car reads a solid 14.72V(no fluctuation) while running.
What do you all think!!??
Thanks
Warren
JFB has excellent powers of observation!!
Thrilled we all learned something and a happy out come.
Yes David, But let's get back to my question....Are my readings in the normal range? And why does the meter read (bounce) between 14.7 and 15.3 while car is running instead of a solid solitary reading?
And if readings are normal why is gen light in dash blinking on and off!!???
12.7 VDC is good for just the battery
14.7 running is good, showing the alternator is charging
the swing and the lamp on . . . not good
did you ever say if you have the original "mechanical" regulator, or a solid state, or even a built into the alternator
here is a drawing of the original charging system, showing the intial energization of the alternator field through the lamp and then the switch over to self excitation once spinning. notice the relay that uses the center tap of the stator 3 phase windings
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Thank you JFB!
I would have to check on the alternator/regulator to see.
Car was totally nut and bolt restored by Dennis Quella at Pantera Performance in late 1990's prior to my ownership.
I will check restoration receipts to answer your question.
Your thoughts?
the G/R wire from the alternator to the S terminal on the regulator is poor connection OR the "switch over" in the regulator gone bad.
the volatage swing sounds like something the mechanical regulator would do normally, where as a modern solid state would hold voltage smoother
Hi JFB
receipt says Alternator OEM type and voltage regulator 1997
Only 1000 miles driven since resto!
Thoughts?
Thanks
my "WAG" is purely based on an acadimic view of the drawings. . .
for the intermidiant lamp,
Loose wire possible (in no particulair order)
the Y wire from starter relay to regulator A
the G/R wire from the alternator to the regulator S
there could be loose wire internal to regulator causing the voltage on the G/R wire to faulter
the transfer relay in the regulator going bad
as for the swinging output voltages. . .
this seems to be common for original as indicated by amp meter. I really wish i was in my prime and had access to investigae this condition as it seems to be the type of problem I enjoyed solving. my guess is it could be midigates with the addition of filtering the stepping field current generated by the mechnaical regulator.
If a solid state, then the regulator is going bad as I would assume field current stabilization is part of that design
given these are just my wild arse guesses, I will bow to any others comments
Thanks so muchI will get back to y'all once its figured out and fixed!Sent from my Verizon, Samsung Galaxy smartphone
Again good solid connections and low resistance in your grounds are important.
I had replaced the stock alt with a third gen Ford alt. Internal fan , internal regulator. After 2 seasons the gen light would blink and the epanded scale volt meter would vary about 1 volt. Thought the regulator was failing. Nope regulator was a little loose on the rear of the alt case.
At the grounds I mentioned earlier on the transaxle and front compartment I went to the hardware and bought "external tooth" lock washers . They dig into the ring terminal and stud.
A last resort after checking all the connections would be try a different regulator. 1997 would be in the solid state era. They are cheap at the parts store , but if you still have a bad connection somewhere it would be a waste of money.
Again the search function on this forum should bring up a wealth of information on what other members encountered.
Remember to work safe , lots of juice in the battery and working on the regulator , through the wheel well you can get squashed.
The schematic JFB sent you came from The Pantera Place.
Then click on technical and there are simplified system schematics.
Good luck with repairs.
That's awesome David
Thank you so much!
Will keep you posted
Warren
As if you need any more input ... how old is the car's battery, and are the cells all full? A healthy battery has very low internal resistance, and the voltage measured across it should not vary much if at all.
I have a question for the group.....
Can a slightly loose cable on the negative battery terminal cause fluctuations in the voltmeter readings 14.7 to 15.3?
Yes, I think that is quite possible. Loose connections, bad grounds, and corrosion cause all kinds of electrical problems. An easy fix and see if the problem goes away.
Just because the engine cranks and runs does not mean you have quality grounds and connections. More modern , computer controlled engine management systems run a ground to each sensor. A few 10ths of 1 volt do make a difference.
Connections need to be clean , tight , and mechanically sound. Wire splices and terminations need to done right. The toothed lock washers cut into the metal , paint is not a conductor. Silicone grease they sell at the auto parts for light bulbs is a good addition to inhibit corrosion in the future.
I confess that I even ran a ground wire from the grounding stud on the altenator to the panel the voltage regulator was mounted on. Remember I now have the internal regulator style alternator but ground is still vital.
I am a retire electrician . One motto is , " If you can't fix it with a hammer, it must be elctrical."
If electrical is a mystery there are good books on the subject. I have several books by Tony Candella , on basic automotive wiring. Purchased on Amazon.
amazon.com/Automotive-Wiring-Electrical-Systems-Workbench/dp/1932494871/ref=sr_1_1?crid=3EUGP80HQ7O3Z&keywords=automotive+wiring+and+electrical+systems&qid=1576221706&s=books&sprefix=automotive+%2Caps%2C803&sr=1-1
There are 2 volumes and a EFI conversion book.
Thanks again David!!
Your welcome!
UFO-LOW has a good point that the battery should be in good condition and fully charged to be able to evaluate the charging system.
Every thing JFB said is spot on and the schematics are good to see the circuit.
The connections on the factory amp meter are known to get over heated and burnt . A peak at them is worth while. Remember to take the battery cable off when in the sub dash. It is "hot" and not fused!
Until you examine and repair all the connections in the charging circuit , you might be wasting money to just throw parts at the situation.