My brother and I have been working on his 1970 F250 w/ a 360. At first we were having issues with the alternator so that was replaced. We are still having a problem getting the truck to charge properly. When the engine is running, it is showing about 12.5volts on the multimeter. After going through the wiring, we’ve determined that all continuity is good and set up correctly. This lead us to think it was the voltage regulator. So, we tested that by pulling the plug and jumping the “A” and “F” ports on the plug in. This made the multimeter jump to nearly 16volts showing that the voltage regulator was suspect.
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As of now, we’ve replaced the regulator, plugged it in and turned the truck on…Again, it’s only showing 12.5 volts.
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What are your guys thoughts on this? What should be the next step we take? Any ideas would be great.

 

certainly your on the money, im not familiar with the older american charging systems, but if their anything like the bosch systems here in Australia check the regulator has its power on the correct terminals (Constant, ignition and maybe an earth?) Bosch only run 2 pin regulators which makes it easy

 

Have the battery load tested. Make sure all of the wire connections are solid and not corroded, especially the battery ground wire attached the the engine and make sure the amp meter gauge in the gauge panel is connected and the printed circuit board has not burned out.

I just had the same problem with my 1970 F-250 390 charging system. replaced alt., regulator, and battery. just like you, I could not get over 13 VDC. After checking and replacing a few questionable wire connectors. I took the alternator to autozone to have it checked. Turns out the "new" re-conditioned alternator was bad too. I returned it for a refund and went to NAPA. now I get 14.5 VDC. at idle.

 

Have the battery load tested. Make sure all of the wire connections are solid and not corroded, especially the battery ground wire attached the the engine and make sure the amp meter gauge in the gauge panel is connected and the printed circuit board has not burned out.

I just had the same problem with my 1970 F-250 390 charging system. replaced alt., regulator, and battery. just like you, I could not get over 13 VDC. After checking and replacing a few questionable wire connectors. I took the alternator to autozone to have it checked. Turns out the "new" re-conditioned alternator was bad too. I returned it for a refund and went to NAPA. now I get 14.5 VDC. at idle.

 

Glad Im not the only one this is happening to. So I will enlighten you on what I did. Got the truck going this summer and put a new deep cycle Interstate battery in it. Made it all summer and into January before I started having problems. Did a Starting and Charging system test on it and determined the alternator was bad. Put a new Motorcraft in it. literally lasted a week and once again bad battery. So got it warrantied and still wasnt charging. Went to Napa and got a new voltage regulator and it charged once again for about a week. after going through all the same steps as you did and another regulater I got upset. My father ended up being the genious and put a electronic voltage regulator off a late 70s ford. Havent had a problem since. For the 12 bucks or whatever it was its worth seeing if that fixes your charging system woes.

 

After looking at the schematics (a lot), I think I finally zoned in on the actual problem...correct wiring, or lack there of.

The plug to the VR has 4 designated wires going into it, labeled F,S,A, and I. Here's how the plug looks vertically going into the VR on our pick up:

I- No wire
A- Yellow- To solenoid
S- Green w/ red stripe- To harness plug
F- Orange- To field

Now, the '69 and '70 schematics both have the same wire number designation and it looks as though the stock wiring was like this on the plug:

I- Green w/ red stripe- To harness plug
A- Yellow- To solenoid
S- White w/ black stripe- To stator
F- Orange- To field

What do you all think? Could it be?

Also, for what it's worth, the alternator that was replaced didn't have a stator post. Only the Battery, Field, and Ground posts.

 

I thought I'd give you all an update and a thank you. After reading through numerous threads, I found that the "S" Green/red wire needed to be hot when the ignition was in the on position.

We went out and tested it and, of course, no voltage. So, we hooked that wire up to a switched lead and it worked perfect. The wire is getting 12v when the ignition is in the "on" position.

We started running the truck and the battery was charging steady at 14.62v. When we turned all the lights on, the voltage dropped slightly to 14.57v for just a second and then went right back up to 14.62v.

So thank you guys for the good information on this website.

 

Sounds like what's wrong with my truck... and I've also got the 3-wire connector coming off of the VR. Well, it's kind of a three and a half wire connector - there seems to be a test point wired into the connector, to check the "A" pin on the VR.

So it sounds to me like "S" stands for "Switch", and not for "Stator".

BTW, I'm pretty sure the wiring diagram you showed above isn't the one you need. I believe the "I" contact from the VR would drive the Amps INDICATOR (light), if you had that on your dash. I'd bet that yours, like mine, has an Amp METER on the Instrument Cluster. Since the current flow is through the wiring, it doesn't need the "I" wire (#904) to drive a light; the meter is driven by other wiring. You should try to find the wiring diagram that is appropriate for the Amp meter.

(tentative) Voltage Regulator Pin-out:

"I" = "Indicator"
"A" = "Alternator"
"S" = "Switch"
"F" = "Field"

For trucks with Amp indicator:
"I" = Wire #904
"A" = Wires #152 & 152A
"S" = Wire #4
"F" = Wire #35

For trucks with Amp meter:
"I" = Not Used
"A" = Wires #152 & 152A
"S" = Wire #904
"F" = Wire #35

Come to think of it, "S" may stand for "Stator" if there's an Amp Indicator.

 

Regulator gets switched power.
Regulator goes to S which is stator and F which is field. (regulator adjusts voltage to f to regulate charging. More voltage to f the more it charges until it self destructs... If it could)

 

Old thread, huh?

Easiest way to fix all the charging problems is by far the 3G swap. It completely eliminates the regulator and a whole bunch of wiring.

 

Holy crap!!! Yeah
I replied to the op other thread (ebrake not staying engaged), and then because he only had 5 posts I figured I'd see where else he posted... And apparently he last posted in 2010. Haha. I didn't even look at the dates.

Easiest way.... Buy a 100a gm 1wire, drill mounting hole to 1/2" and bolt it in place. Anything with external regulator I get rid of. And the gm alt is super cheap.

 

Hey guys. Glad to be back. Sadly, my brother and I corrected the issue then he never did anything with the truck. He sold it a year later for a 10% loss.

I, on the other hand, became a happy owner of a 1990 F150 XLT Lariat on Sunday so I will be back and posting. It feels good to have a truck in the driveway!

 

Welcome back Clark!

 

Motorcraft electronic alternator voltage regulator introduced in 1982 (E2PZ-10316-A / Motorcraft GR-540-A), replaced the points type alternator regulators used 1963/81.

Regulator has a flatish aluminum cover with MOTORCRAFT embossed on it.

E2PZ-10316-A was replaced in 1990 by FOPZ-10316-A / Motorcraft GR-540-B

 

About 30 years ago I went with a GM one wire internally regulated alternator also. It's lasted this long so far.