Good Evening,

So I am finishing up a centech harness install and was making sure alternator was working.. Nope.. battery voltage drops over time while running. Getting about 12.4v. So I pulled the regulator and jumped FLD to the battery and I am getting full charge just fine from the alternator (17+volts).

Would this mean the regulator is bad? Its a brand new regulator that I put in maybe 2 weeks ago. Was working fine before the harness swap.

Thoughts? I tested the centech connector to the regulator. The S terminal is getting like 0.80v, the A terminal is getting 12.4v from battery.

Tried rev'ing it up above 1200 RPM's to see if maybe regulator doesnt kick in at idle. Could it be voltage is too high in battery and it isnt needed so its not on?

Thanks!
Jeremy

 

You didn't mention any voltage at the I terminal which is your switched power. Without it the regulator will not charge.

 

My harness didnt include anything for the I terminal. I was under the impression that the I terminal was for a gauge light (which I dont have)

 

I- Means Ignition not Instrument...............

 

What would that run to?

 

Also, my AMP gauge isnt working on the dash. No clue if it worked before or not since all the gauges were not hooked up from the PO.

Would the AMP gauge and the I terminal have anything in common?

All my documentation says that the I terminal is only for a generator (idiot light) light and that if you have an ammeter (like me) do not use the I Terminal

I think I'll start with another new regulator and see what's up.

 

The " I " is a 12 full Volts to the Coil during Starting if you are running a Resistor.

 

Check my memory but I thought there is about a 10 gauge wire from the Battery Terminal own the Alt. to the Neg side of Amp gauge and Pos side of gauge to the Battery side of Solenoid. A own the Regulator should have 12V from Ign Switch. F should be to Field wire Terminal own the Alt. And S to the Stator own Alt.

 

My amp gauge wires run from different sides of the "shunt".

I do not have a gen light and I do not use a resistor (pertronix ign).

I'm going to go grab a new regulator and post back results.

 

Good news! Got it working. Wasnt the regulator.. or maybe it was...

It was the I-Terminal. Even though the ford wiring diagram, centech diagram & instructions and centech themselves all state that if you have an ammeter the I terminal is not used. That its only used with the gen light. Well maybe my dash was swapped or something because as soon as I apply 12v to the I terminal in the regulator it starts charging.

So I am not going to try and figure out why, just going to fix it and move on.

Thank you for all the help!

 

Are you by chance missing the wire from the starter solenoid to the regulator?

 

It's there and I verified I have 12v on that terminal. My ammeter isn't working. Would that have anything to do with it? Read it was pretty common that they don't work so I ignored it for now.

 

You're right, most of the Amp meters don't work. Many people change them over to a Voltage Meter.

 

You were also not getting the proper reading on the "S" wire in your case. Was that test with the key in the ON position, or OFF?
If ON, then you should have been seeing close to battery voltage. And you're correct about the wiring.

Did you verify that your charging voltage was just 14 to 15 or was it higher by any chance?
I suppose if it works as it should and does not cause any battery drain when the key is OFF, you can leave it that way. But you were on the right track with your first wiring scheme and just needed to see 12v on the Green w/red wire when the key was switched on.
As you can see in the diagram (sort of!) Ford used two completely separate methods of wiring the regulator. In cases without the ammeter, all four positions were used. In the case of having an ammeter, only three positions were used. F, S & A with I left blank. So Gray Scar is correct for wiring without the ammeter and maybe that's why yours does not work now. Granted, most of them don't, but if yours did before the swap and you didn't mess with any of the other wires during the whole harness install, it should still work.

I don't know "regulator theory" by any stretch, so maybe you do indeed have a defective regulator that does not work with the switched S wire connected, but does with the I wire connected.

You can try disconnecting the I wire from the regulator and applying it to the S wire and see what happens.
By the way, which wire did you connect to the I terminal of the regulator? Same one connected to the S terminal before, or different?
Is the Centech harness specific for this year(s) trucks? Does it have the proper circuits for the ammeter or not? Most do not, so maybe the reason it's not working has more to do with the lack of circuitry in the new harness than any fault with the gauge or charging system. Not sure, but it's a possibility.

Paul