Good afternoon all, I am looking for some assistance on the operation of the charging system. 1968 442 with 400, external regulator. I have replaced the regulator, radio condenser and the generator with new parts but my light is still on. I have tested the voltage at the battery with all new components while running, it's only at 12.1 volts. I can diagnose very well but I don't have the slightest clue on how the system works. Any help is much appreciated!

 

Are you saying with the car running you measure 12.1V at the battery? You should be getting ~14.3V w/ car running, alternator running at the battery.

EDIT: BTW, that's w/ all systems turned OFF in the car.

 

You're most likely thinking what is it I don't understand about your post. I'm just double-checking to ensure we're on the same page - 12.1V measured at the battery w/ car running (at idle) & all accessories turned OFF you should get 14.3V at the battery.
Assuming you have a 10DN (55amp) alternator (many folks convert alternators) and you have the correct external VR:
(1) Double check your ground wiring - nice & clean from (-) battery post to engine block & engine to firewall. Remove hardware (screws, straps, etc.) brush w/ sandpaper or otherwise to ensure good ground(s). VR gets its ground from the firewall.
(2) Double check your wiring is correct - blue and white wires are correctly oriented per the wiring diagram & ensure wiring is same as wiring diagram (color wiring diagram is in the 1968 CSM).
(3) What was the reason for installing a new ALT & VR? Because the dash GEN light came on? Which did you replace first (if this is the reasoning) ALT or VR?
(4) VR's are well known to be either the incorrect or simply bad new ones - it happens more often than you can think of.

Here's the 1968 wiring diagram - double-check your wiring. If you have the part number of the alternator and the VR that would help to identify any possible mismatches. If you have a picture of the alternator case and the wiring plug harness leading into the alternator that would assist since many folks here have seen it all - alternators rebuilt incorrectly, wrong wiring, incorrect case, etc., etc.



10DN Alternator

1968 Wiring Diagram

 

Unplug the regulator, leave it unplugged, jumper the F terminal to the 3 terminal on the regulator plug. Start the car and check the voltage.
If 14V or more bad regulator,
If no increase in voltage, bad alternator or a wiring problem to the alternator, see the wiring diagram Norm supplied.
If your alternator is bad I suggest using a local auto electric repair shop to rebuild yours.
Good luck!!!

 

As per what Sugar Bear suggested to (test) jumper F terminal to 3 terminal on the VR plug, here are the terminal numbers F,2,3,4.

 

I had a similar problem. To clear the trouble (after replacing bad VR), I disconnected and cleaned all the electrical connectors among the generator, regulator, power distribution block, battery. ground straps, and ignition switch. When all connectors were cleaned with 100# emery paper and spray-can electrical connector cleaner, then re-assembled with dielectric grease, no more GEN light once car is running.

 

Okay! Thanks for all the generous help guys, I just disconnected the VR and jumped terminal F and 3, my meter was reading 16 volts. Suggestions on voltage regulators? I purchased mine from a company called Inline Tube here in Michigan.

 

Once the VR is replaced and the voltage is good the amperage output should be checked.

Good luck!!!

 

Purchase a VR from your local NAPA store, No shipping charges, etc. Which manufacturer I don’t know. Go to local NAPA store they’ll help you. Also, see what’s listed on Rockauto.com. for manufacturers. Others may reply w/ a known good reputable VR manufacturer for your car.

 

Sometime the cover from the old VR will fit the new one to keep an original appearance.

 

Before you replace the VR, clean the connectors to the VR and try again, just in case it was a dirty connection problem.