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Pulsing lights at idle - how old is this regulator??

2124 Views 56 Replies 10 Participants Last post by  matnetik
Here’s what I know - lights pulse at idle - will get some video this weekend.

I believe it’s just the headlights, not sure if it’s inside as well
3 wire alternator, new cables (unsure how old it is but keeps everything charged and battery reads 13.5v atm)
New solenoid and new battery
New instrument panel regulator
New ground strap from alternator to block, from block to firewall and to radiator
All new bulbs and light housing / cleaned connectors
Just ordered a new headlight switch because mine has been a bit finicky.

I am thinking it’s this 40+ year old voltage regulator or is this a replacement? Easiest way to test? Or just replace? Any recommendations for a solid state unit? Doesn’t need to look factory or anything but would love plug and play. As always, thanks!
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Great replies and thanks as always! Will start by getting this thing a better ground, and I’ll pull the cover off to see what’s underneath. @Woodchuck (I owe you multiple beers at this point haha) can you point me in the direction of what condenser I need? @awhtx & @Hemikiller appreciate the link, not trying to cheap out so will buy the good one!
Hi. It appears that you have unwittingly wondered into the weird world of electrical idiosyncrasy resulting from bad or faulty grounds. That is a common topic on this forum and discussed regularly.

This is what I did, although I'll admit that I might have gone a bit over-board. I ran a 12awg black wire from the battery terminal and daisy-chained it to most everything of electrical importance under the hood. This included the starter solenoid, alternator, voltage regulator, Duraspark box, plus into the cabin where I used a bolt as a post to connect several extra grounds to instrument panel and radio. I used internal serrated washers or terminals to insure a good electrical connection.
As I understand, if you have any aluminum add-ons (radiator, intake, water pump) I'd run a wire to it as well. Very small electrical resistance can cause current which, over time, can cause corrosion with those items.

Also, I've always been steadfast suggesting that everyone get the Ford Electrical Assembly manual for their year car. It has all of the wires (including colors), connectors and other electrical components of the car, and includes the routing of all the harnesses. Very useful.

Good luck. Keep us informed of your progress.

Yeah I recently went through a replaced all the ground cables and made sure straps were secure. Cleaned up and replaced the alternator cables and ran new inline fuses / tubing to tighten everything up On the passenger side, need to do the other side of the engine bay now. All my other electrical is pretty solid, obviously random things come up from time to time and I stumble upon shortcuts the previous owners took. Thanks for the great info and explanation, going to order a solid state regulator and that suppressor above. I am sure it also has to do with a mix of LED and halogen bulbs, might need to add some resistors here and there.

As far as the manuals, it’s the first thing I did when I bought the car! Got them all
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You are attacking the problem smarty and methodically. Nice.
Great choices for the library. I’d still get the electrical assembly manual as it has lots of detail that I don’t think you’ll find in those three. You’d be surprised. I’ve found it indispensable.
Ah! For some reason I thought the electrical / vacuum diagram one I have was what you were talking about - will have to snag the electrical assembly for the collection - these manuals are a MUST HAVE
Okay! Took the old regulator out today and installed a new Autolite from NPD, also got the suppressor and correct mounting bolts. I have a new headlight switch I also need to install - didn’t actually get a chance to test the lights since it was during the day but no issues on the install so there’s that - ha - will report back. Also had to take the old one apart just to see what was going on in there, look at those wound coils!


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You'd be surprised to know that unless the relays and associated electronics are damaged, a bit of dressing of the contacts with a point file and some adjustments will bring that regulator back working just fine and dandy.
Oh yeah I bet with a little TLC it would be good as new! Btw appreciate your suggestion on the suppressor!
Installed the new headlight switch (this needed to happen regardless, was hard to get the dash lights on because the old unit was finicky), new ground from block to firewall, VR is grounded properly, ground to radiator support and the lights are still pulsing in Drive or Park with the engines RPM.

I suppose next test is the alternator? I have a new battery, need to check voltage off and on with the car as well. I recently replaced all the wiring for the alternator, starter and solenoid / coil.


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Well I am assuming this answers my question on the alternator?

With the engine on the DC fluctuates between 14.8 up to 16V
AC fluctuates between .1 and .5V

I suppose the next question is, if I were going to replace the alternator, which one? I would want to go with PowerMaster for sure but there are so many to choose from! If I understand correctly, this is a 3G alternator setup?


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I'm not concerned with the marginal AC voltage as much as the high DC voltage. I wouldn't want to see DC voltage much exceed 14.7v at the battery terminals at 1,500 rpm or so. You might want to check out a different brand VR. If you decide to go with an alternator swap, I'd go with a 93-95 Aerostar 95A 3G unit with internal regulator... pretty much a direct bolt-in with some minor wiring changes.


I did start the engine seconds before taking this video so it was nowhere near warm but yeah pretty wild changes there. Going to run to UPS and will measure again once I return to see if there is any changes when warm.

I am all good with wiring, that's my speciality, you wouldn't recommend the Powermaster units? I've read good things about them, just curious. The VR is this one from NPD - VOLTAGE REGULATOR, ALTERNATOR - #10316-2A - National Parts Depot
I recently did the swap from the stock 1G alternator to the 3G alternator. It was pretty simple. I think the hardest thing to do was reclock the alternator case, and that is not that difficult. If you decide to go with one of the Ford 3G alternators, you don't have to worry about the stock voltage regulator anymore because the 3G's are regulated internally. Here's the write-up I did on my installation:

I recently replaced the wiring on my alternator and it has three wires going to it - wouldn't a 3G alternator just be plug and play at this point? I am slightly confused on the difference between 1G and 3G, always though it had to do with the wiring
Ah, fully understand now. Is there any reason I would need to go to a 3G? Powermaster makes a 7078 1G 55-75 Amp unit for $110 bones and it's a simple replacement. I have factory A/C, radio with 5 speakers and electric power steering. Wondering if this is enough or should I go the 3G route - just asking questions here!
Great info, here’s the current plan, I ordered the Powermaster 7078 1G alternator since I have read both good and bad reviews, couldn’t find it on NPD so I Amazon’ed it. Going to pop it in, if it fixes the issue, amazing! If not, I’ll send it back and dive down the 3G route - I hope this solves it since I literally just purchased the new voltage regulator and noise suppressor. Not sure a headlight relay would change anything given that ALL my lights pulse, both the halogen and LED’s in the front end and interior. - Anyway, as always - thanks for all the help and will report back with info!
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Well I installed the new alternator and no luck. Lights are all still pulsing, I did measure when I first started the car and the voltage was all over similar to the old alternator in the video from above.

In the video below, this measurement is after 10 minutes of running. As you can also see, all the lights are pulsing with the engine RPM - all exterior and interior.

So one question before I go the 3G route, is it possible I mixed up my “field” and “power” wire when I re-wired everything? Would the alternator still be charging the battery? Would the car seem normal with these reversed causing the pulsing? Just wanted to ask if anyone knew. Might test them tomorrow.

Also, thoughts on the PA Performance 1G to 3G kit vs purchasing an alternator and their “VR thingy” to make the Ammeter work? If I go the 3G route, I’d like to keep it as clean and simple as possible! Thanks in advance, as always!

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Which it will do as the regulator cuts in and out to keep the alternator from overcharging. Since you've switched to a lot of LED's you've reduced the load on the charging system to where the regulator is "cycling", recognizing an almost fully-charged battery....

Let my brain think for a minute... you said your alternator had 3 wires... a big one to the BAT post, a ground and one to the FLD post.... is that correct? That means you should have an ammeter in your instrument cluster and the GRN/RED wire to your voltage regulator goes into the "S" location? I wonder if your solid-state regulator has enough resistance in the "sense" circuit..... I'd be tempted, if you have a test light, to see what happens when you hook your alligator clip to ground and back-probe the "S" plug on the regulator with the test light.... with the engine idling, to see what it does for the "pulsing"....
The only things that aren’t LED are the headlight bulbs and the fog light bulbs. Everything else is LED.

And correct on the three wires, BAT, ground and FLD. I do have an Ammeter (doesn’t really do much other than sit in the center haha,, probably just need to scrub the connectors). I have a test light, will give this a shot and see what happens. Thanks for the quick response here as always -

I’d love to just make what I have work if possible but ultimately if the 3G solves the issues I am 100% okay going that route. Given that I have tried a new alternator, replaced the VR and noise suppressor I would think that might be the next step. I would try headlight relays or replace the harness but given that ALL my lights pulse I think there is something else going on.
Haven’t had time to test yet, unfortunately had to have dental surgery on Wednesday. I decided to return the Powermaster I bought and ordered the 1G to 3G PA Performance kit, regardless if it fixes the lights pulsing or not, it will be much more solid to be on a 3G alternator as many have suggested. Will update once installed - cheers all
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Was about to put the old alternator back in, but before I do I decided to look at the wiring from the regulator - does anyone know if this is correct?

Well a quick search shows that yes, this is correct for a 68’ with an Ammeter - will try to back probe the green/red wire now -

No change on back probing the green/red wire. Question though, is the orange wire supposed to have any power? With ignition on or off the orange cable shows nothing, assuming this signals when the charge is happening - Just tested resistance and it is wired to the field post on the alternator which I believe is correct.

Yellow and green/red both show 12.8 v


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Installed the PA Performance 95A alternator with their dummy regulator and in-line fuse setup today. I think I did everything right as far as the wiring goes. The good news, WE HAVE SUCESS! No more light pulsing!! I mean at all, it was starting to rain so I could only run the car for a few minutes but they looked solid!

Now my only concern, with all accessories off (the radio may have been on) and the car on, I was getting 12.35 volts at the battery but it was steady, maybe .01 fluctuation which is awesome but it’s definitely not charging.. Pretty sure it’s the ground, I grounded from my engine ground strap to the alternators housing (see in picture below) and I should have grounded to the center bolt as the instructions recommend. I think this is why it’s not charging.

Or is it because I didn’t connect the original BAT wire from my harness to the B+ terminal? I was under the impression to not use the wire anymore since the 6 gauge cable/fuse is going to the solenoid.

As it is now from my cars harness to their harness/alt-
-orange (field) wire soldered and crimped to green/black
-yellow from their harness to B+ on alt
-white/black from their harness plugged in with pigtail to alt
-ground from engine block/ground strap to alt chassis (might be in wrong location)
-6 gauge wire with in-line fuse from B+ on alt to solenoid battery post
-original BAT wire from car is taped off and not being used


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What have you got connected to the green/red wire at the alt pigtail?
That’s my orange wire which goes to the VR - the field cable, 12v with ignition is switched on - I thought it was green/black for some reason - I believe it‘s the exciter wire and goes to the F terminal on the VR
Do you have battery voltage at the "A" terminal on your dummy regulator?
Will check tomorrow after the rain, I am assuming that the “A” terminal runs parallel with wire that was previously connected to the alternators BAT meaning I need to connect it to the B+ terminal on the alternator? I saw someone did that in this thread and it worked for him - thanks for the late reply
See the splice in the original harness. The "output wire" from the alternator goes in 4 separate directions (regulator, inside the passenger compartment for the "feeds", the ammeter and to the battery, via the common lug on the solenoid. Lacking these splices in the replacement harness, wires need to go to a common point. In the case of the output wire these can be picked up at the BAT terminal on the alternator or the common lug on the solenoid. It doesn't matter which, other than for the ammeter.... The ammeter is a "special animal" as it's a shunt type and both wires going to the ammeter are exactly equal in length and the wire spliced to the alternator output is located at a point that effectively "zeroes" the gauge.
Brilliant reply - will solder and add a ring connector and put it with the B+ terminal - should solve the issue - the PA instructions don’t mention this wire so it was a bit confusing and I was worried about high amps traveling through it but I suppose the 4G battery cable with fuse takes care of that!
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