Hey guys. So I have a 1983 F350 with the 6.9. My old alternator died…11 volts while running…so I installed a new one. I also installed a new voltage regulator from NAPA, along with a new connector on the regulator. I have voltage at all times on the “A” terminal on the regulator and have voltage on the “S” terminal with the key on. I also grounded the body of the regulator to the ground on the alternator because I heard that can be a problem. After all of this it is still charging at 18 volts! Bought another regulator, same result. Tried going back to the old one, same result. I’m at a loss on what the problem can be. Everything is new and tight. Thanks in advance for the help.

 

Ignore my dumb*** Figured out the problem…my multi meter was reading wrong. What are the chances…my luck. HAH.

 

not your fault the multi meter was bad...
it happens to the best of us.

 

Those Chinesium meters!
Find a used Fluke that's in decent condition, better than new Chinesium one.
Mine's 40yo and still as reliable and accurate as new.

 

i use the harbor freight $9.99 meters. cheap enough that if someone "borrows it and forgets to return it" no big deal.
i check them against my simpson 260. if they do not read true i simply return for another.
my simpson is another matter. that never leaves my sight.

 

How about charging problem, no charge from the alternator even though it tested good?

 

for a no charge with a test good alternator first thing i do is check the fusible links off the battery side of the fender mount starter relay

 

He took the wiring harness off that runs between the alternator and voltage regulator and was apparently able to get continuity through that.

Testing the passenger side battery terminals with a multimeter showed a voltage around 12.3 so when we fired it up last Saturday. I know the battery + cable off that passenger side battery has a smaller 10 or 8 awg power lead going to the one side of the starter relay, and the truck started fine so I don't know that the relay itself would be the problem.

Are there more fusible links to check? Like is there something between the voltage regulator and the starter relay that could be the problem? I don't know what all those ring terminations are that stack onto the hot side of the starter relay. That's different than how it is on my 99. His truck is I believe an 88 or 89 7.3/ZF5

 

all wires go to battery side of starter relay except the one to the starter, and the small trigger wire.
there should be 2 fusible links on that terminal. one in cab power, and one for charging circuit.

 

Oh, the red 8 awg wire to the battery isn't supposed to be on the hot post with the other ring terminations? I believe I saw 4 ring terminations on the starter relay hot post. One was the feed from the B+ on the alternator, one was in cab power I assume (made the hood light come on) and I have no idea on the other 2.

I suggested poking the B+ terminal with the multimeter to see if it was putting anything out as far as voltage but we couldn't get it running again because of batteries getting tired.

 

where does the "red 8 awg wire" go?

 

From the passenger positive battery terminal to the hot side of the starter relay.

 

ok. so that is the power feed to the relay. all wires should connect to that terminal except for the small trigger wire from ignition switch, and the large wire to starter itself that connects to the other large terminal on the relay.

 

How about the voltage regulators on these old setups? Is there a way to test them or is there a general consensus that the Motorcraft one is best and to stay away from the parts store units? We’re still trying to figure this one out.

 

Yes an electrical rebuild shop usually has a tester for regulators. Not sure if Auto Zone and those sorts of stores would have one. Doubt you can buy a USA made regulator anymore. I would install a solidstate style if you need to replace.