Check out of charging system

[patrickt]

I understand; I just want to know what the specific voltage number is when the plug is jumpered and you're revving at 1500RPM.

[DanEC]

Originally Posted by patrickt

I understand; I just want to know what the specific voltage number is when the plug is jumpered and you're revving at 1500RPM.

That reading comprehension thing again. I'll check voltage.

[patrickt]

Originally Posted by DanEC

That reading comprehension thing again. I'll check voltage.

And when the engine is running and, presumably, the alternator is working, then the "system voltage" will be pretty much the same anywhere on the system, absent a big load somewhere causing a voltage drop (which we don't have here).

[DanEC]

12.7 volts. No increase as I rev the motor up.

[patrickt]

Originally Posted by DanEC

12.7 volts. No increase as I rev the motor up.

Pull the alternator, take it up to your local parts store that will bench test it, and have them check it. All signs point to a bad alternator.

[DanEC]

OK will do

[patrickt]

Originally Posted by DanEC

OK will do

Maybe as one last check, leave the jumper wire on the voltage regulator plug, start the engine and rev it to 1500 RPM, and measure the voltage at the terminal that has the big orange wire on it there at the alternator. If it's 12.7, pull the alternator and take it to the store for a bench test.

[DanEC]

From orange wire terminal on back of alternator to ground for voltage regulator - 12.5 volts (battery geting a little low). No change when I reved it up. The regulator was plugged in.

Unplugging the regulator and jumping the two terminals the voltage from alternator to regulator ground was 14.5 volts and as I reved it, it was climbing to 17 to 18 volts.

Looks like alternator is putting out OK. Back to the regulator?

[patrickt]

Originally Posted by DanEC

From orange wire terminal on back of alternator to ground for voltage regulator - 12.5 volts (battery geting a little low). No change when I reved it up. The regulator was plugged in.

Unplugging the regulator and jumping the two terminals the voltage from alternator to regulator ground was 14.5 volts and as I reved it, it was climbing to 17 to 18 volts.

Looks like alternator is putting out OK. Back to the regulator?

Yes, the alternator is working. Try whacking the regulator with the handle end of your screwdriver and then plug the plug back in and wiggle each wire going in to each side of the male and female ends of the plug.

[DanEC]

The whacking-it-with-a-bigger-hammer trick didn't work and I've had that thing plugged in and unplugged so many times I'm about to wear it out. I went down and ordered a mechanical unit. At least if it doesn't work I can take it apart and figure it out.

This is the same frustrating experience I went through with my 67 GTX last summer and it was the electronic regulator on it also.

Thanks for the help Patrick.

[DanEC]

Alas - my luck with fixing the turn signals did not hold true for the charging problem. New regulator and bench tested the alternator (OK) and still no charge.

Going to start over with testing again. Any other suggestions are welcome.

Dan

[patrickt]

If the alternator checked out, and the VR is not broken, check the continuity of the field and stator wires running between the VR and the alternator, and check the continuity of the the orange wire running from the alternator to the fuseblock. Then double check the grounds to both the alternator and the VR and, if all of that checks out, and the connections are tight, then it is metaphysically impossible for the system not to charge.

[DanEC]

Everything seems to check out but it doesn't charge. Jumpering across the VR terminals and checking the voltage from the + starter relay to the neg battery cable I get 14.5 volts at idle. Ammeter is pegged. Plug the VR in and I get 12.5 volts throughout the the system and a slight discharge from the distributor I guess.

I put my VOM in the VR jumper circuit and got 12.4 volts is all. No change when reved up.

I ran continuity on all the wires and all passed. I checked all the grounds and they test good to the engine.

Seems strange that with the VR jumpered I'm getting 14.5 volts at the starter relay but only 12.4 volts between the yellow and blue wires in the VR plug.

My battery was down to about 50% so I put the charger on it. That's about my last hope - maybe it's just too low to charge somehow.

[patrickt]

Tell me if this is exactly what you are doing, since sometimes posting on a thread can be misunderstood:

When my VOM is place on my battery, with the car off, it reads about 12.7 volts. If I leave the VOM on my battery, and start the car, while it is running the voltage is still about 12.7 volts.

With the VOM still on my battery, if I unplug the connector to the voltage regulator, and jumper across the first and third tang, and leave the plug out of the voltage regulator, when I start the car and rev it to about 1500RPM I get over 14 volts.

Is that exactly right?

[DanEC]

Originally Posted by patrickt

Tell me if this is exactly what you are doing, since sometimes posting on a thread can be misunderstood:

When my VOM is place on my battery, with the car off, it reads about 12.7 volts. If I leave the VOM on my battery, and start the car, while it is running the voltage is still about 12.7 volts.

I got 12.9 volts at battery at rest (charger had been on) and 12.6 volts when I started it. The ignition light is on and my ammeter is showing a small discharge.

With the VOM still on my battery, if I unplug the connector to the voltage regulator, and jumper across the first and third tang, and leave the plug out of the voltage regulator, when I start the car and rev it to about 1500RPM I get over 14 volts.

I have about 13.5 volts at idle and it will go up to 16 or 17 as I rev it up.
Is that exactly right?

Pretty much the same - I just can't get a charge on my gage or the light to go out.

[patrickt]

Originally Posted by DanEC

Pretty much the same - I just can't get a charge on my gage or the light to go out.

Then you've either run in to two bad voltage regulators, or what is more likely, is that the voltage regulator is not getting excited in to functioning via the small charge through the filament of the dashboard light. Make the test changes, as per my Post #4 in this thread, and see if your system then charges properly. If it does, then the problem is the excitation feed to the voltage regulator. You can take your time on fixing that. If your dashboard light is still on after making the modifications I outlined, then you have miswired the light and that is the problem.

[cscobra]

Dan, I have a mechanical VR (Ford reproduction) and initially had the light on/no charge situation you describe. I took the cover off to watch the VR work (hooked up to the car, including ground, but not mounted on the footbox). I noticed one of the two leads to the VR frame from the "bobbins" (for lack of a better term) didn't appear to be soldered as well as the other lead. This was corrected and voila - it now charges. It doesn't seem to get "excited" enough to charge, though, until after the first time the engine has been revved to 1500 rpm or so. Other than that observation, I've had no further charging problems after 200 miles.

Hope this helps - good luck!

[DanEC]

Originally Posted by cscobra

Dan, I have a mechanical VR (Ford reproduction) and initially had the light on/no charge situation you describe. I took the cover off to watch the VR work (hooked up to the car, including ground, but not mounted on the footbox). I noticed one of the two leads to the VR frame from the "bobbins" (for lack of a better term) didn't appear to be soldered as well as the other lead. This was corrected and voila - it now charges. It doesn't seem to get "excited" enough to charge, though, until after the first time the engine has been revved to 1500 rpm or so. Other than that observation, I've had no further charging problems after 200 miles.

Hope this helps - good luck!

I wonder if the same thing may be what I'm dealing with - I just haven't rev'd the engine enough to trigger the VR. Either that or my battery has been too weak. I can't believe that I could have two bad voltage regulators. I pulled the cover on the VR and examined it and found nothing amiss - I think I will give it a try operating it with the cover off to observe it.

I can't bring mysef to start cutting up and modifying the wire harness right now.

Thanks

[strictlypersonl]

The initial trigger to make the alternator charge usually requires a few extra revs. The current drawn by the dash light (to actuate the field current) is marginal without a little extra push. A (~20 ohm) resistor can be wired in parallel to the light to make the system more responsive.

[DanEC]

I will look for a resister at Radio Shack to wire in. I probably rev'd it to a little over 2000 while checking total advance but that's about it. Battery was probably weak also.

Thanks