Pulsing lights or flicker

[DirtDonk]

No. No premade harness that I know of has any scheme for grounding an alternator.
It’s automatically assumed that the alternator is cleanly bolted to a clean engine and that the engine is well grounded to the battery.

I suppose you could always test the ground theory by attaching a single wire to the case of the alternator and then to the battery negative.
Then go drive it at night and see if the lights still pulse.

Of course, you could also remove the ground wire from the engine and move it over to the main bolt attaching the alternator to the cylinder head.
That would surely ground the alternator! I’m not sure what it would do for your starter, but at least it should not harm the alternator that I know of.
GM did that for years. Not the most efficient for the starter perhaps but it was great for the alternator and very convenient for servicing.

 

[428kidd]

So I made a new thick heavy ground . Went from the ground on the battery and went straight to the bolt for the alternator. Made sure the bolt was clean to the engine etc. Put it all together and still pulses. So I'm out of things to check. The alternator is a reman, so may take it in and have it looked over again. I also noticed with the Centec harness it does not use the black post on the alternator, could this cause the issue? Either way off to the celebration today. Wish me well.

 

[Jdgephar]

Double check that there is no rust or corrosion on the bolt of the alternator or anything sandwiched between the bolt and the aluminum frame of the alternator. Everything needs to be clean and shiny.

Check your grounds for the regulator also.

Sent from my SM-G981U using Tapatalk

 

[DirtDonk]

Did you ever mention what year your bronco is?
When you say the black terminal on the alternator, is that the STA terminal?
Unfortunately, the aftermarket manufacturers have changed the colors over the years. Originally used to be red for a BAT, white for STA, and orange for FLD.
From 66 to 72 only the FLD and BAT terminals were used. Only 73 and later had a wire for the STA terminal, and the only thing that did was power the carburetor choke.
Nothing else on a bronco. Other cars, yes. But on broncos and other Fords that used an ammeter, they did not use the stator, or STA post for anything, but choke duties.

I don’t think that would cause any pulsing on its own, but anything that’s connected incorrectly on an alternator could cause problems.
Presumably, the regulator connections are correct and there are only three terminals utilized. Nothing on the fourth. Correct?
Seems like we talked about that already, but I wanted to make sure.

 

[428kidd]

So its a 70, with a Centec harness. I checked all the grounds etc made new ones etc etc. So finally pulled the alternator off . Yes the STA is the one not used. The Sta attaching bolt or terminal would just spin like something was broken. This was a reman Motorcraft unit when i got it serval years ago. Any way back to NAPA and for another motorcraft after doing some digging. Its the same except the orientation of the wires on the back are clocked differently, but it worked. I just got it installed and haven't driven it yet but seems like its fixed. The amp gauge doesnt jump up and down now. So hopefully that has it fixed. I will keep you posted and thanks guys for all the help!

 

[DirtDonk]

Great news so far! Definitely looking forward to hearing the ultimate result.

 

[428kidd]

So updating this a bit. So more that half of the summer all was well with the new alternator. Staring a bit back maybe a month it started to come back I'm literally at my end as to say what the cause is. It doesn't do it at all not running with the lights on. If I load the engine at low speed it will stop, but any other time it flickers or pulses with the gauge hand. It's all the lights from the dash lights , headlamps to tail light and markers. I have some videos but no real way to post them. Again new harness , new grounds , 2 new alternators, 3 voltage regulators.

 

[73azbronco]

I'd clean all contact surfaces, wire brush all battery alternator cables, ground cable from battery to engine block. Clean contact surface of alternator to mounts.. Use some emory cloth all connectors into out of regulator.

You say newish alternator? It could eb a bad alternator or a bad regulator.

 

[Jakedog]

Back in the 90's I had the light flicker on my '75.
One night I got the idea to check all the ground connections. They all seemed fine.
I finally got the idea to get my jumper cables out. While it was running I connected one end to the battery ground, and I connected the other end to a place on the frame.
As soon as I connected to the frame the flickering stopped.

I ended up adding an extra ground strap.
No more flickering.

 

[DirtDonk]

Adding more grounds to Broncos has never a bad idea.
And along those lines, the core support often becomes less bonded to the fender aprons than when they left the factory.
Rust and paint and rust usually have their way. And there’s rust…
You can test the theory just like was described as grounding the frame, by running a jumper wire between the battery negative and the radiator core support, or grounding points for the lights.
In fact, because the headlights, running lights and turn signals all get their grounds through the radiator core support, just add a couple of grounds right now. Don’t even spend the time testing, because it will probably help multiple things.

Take some 10 gauge wire and make some ring terminal ends. You could even go really short and just screw them to the fender apron at one end and the core support the other. Only takes a couple of inches of wire.
Or to do better, run the wire from your main body ground to the light ground at least on one side.
Even if it doesn’t stop the flickering, you will still probably see an increase in brightness.

Without going back over all of the previous posts, do you have a main body ground?
That would be from the battery negative to the body nearby?
They inner part of the wheel well was where Ford put it. But you can put it anywhere convenient. One of the mounting bolts for the starter relay is a common point.
Or create your own point somewhere on the inner fender area.
And then don’t forget to add one between the engine and the firewall.

Which Alternator are you running? If an original style, is there a dedicated ground running between the alternator case and the voltage regulator bolt on the fender?
If internally regulated, is the mounting point clean and bare metal? Or is it painted and/or rusty?

 

[428kidd]

Update checked voltage at battery with lights running. Seems to move as much as the pulse. I'm thinking alternator? What y'all think?

At low idle no pulse and no needle bounce . Give it gas and it's back up.

 

[73azbronco]

do you have a ground cable from battery to block, connection cleane with wire brush?

How old is alternator? Regulator again?

 

[428kidd]

Yes all new wiring, ground from battery to engine engine to body . Frame to body and battery to alternator. All cleaned and checked last time. Alternator is less than a year old napa reman as is the voltage regulator.

 

[428kidd]

Added a temporary ground just to check from the battery to the frame and from battery to body. Changed nothing at all. I think it has to be something in the alternator or the voltage regulator?

 

[73azbronco]

Before you move, have you considered a 3g/4g?

 

[m_m70]

dded a temporary ground just to check from the battery to the frame and from battery to body. Changed nothing at all. I think it has to be something in the alternator or the voltage regulator?

Have you tried going from your battery ground terminal directly to your alternator case using the cables??

are you cleaning up the grounds to clean bare metal?? In your video it looks like you just attached your cables to painted or non clean areas of your core support.

Before you move, have you considered a 3g/4g?

Easy mod. Cleans up the wiring a bit. I went with WH one wire 10 years or so ago and haven't had any issues since.

 

[428kidd]

Have you tried going from your battery ground terminal directly to your alternator case using the cables??

are you cleaning up the grounds to clean bare metal?? In your video it looks like you just attached your cables to painted or non clean areas of your core support.


Easy mod. Cleans up the wiring a bit. I went with WH one wire 10 years or so ago and haven't had any issues since.

Have you tried going from your battery ground terminal directly to your alternator case using the cables??

Yes I did that also after I tested the first one . No I didn't sand the spot on the core support, but the spot on the frame was cleaned. If it was going to make a difference it should have shown up in both the tests if it was a ground issue .

 

[73azbronco]

need to wire brush the contact spot on engine. Or, run a jumper cable battery negative to engine block near alternator.

 

[m_m70]

No I didn't sand the spot on the core support, but the spot on the frame was cleaned. If it was going to make a difference it should have shown up in both the tests if it was a ground issue .

Maybe just exchange it then. Should still be on warranty.

 

[428kidd]

So another Napa remain alternator and a the better napa brand regulator . Ground going from battery to engine. Engine to alternator directly. Small ground wire to case also and small ground straight to the VR. Seems to have fixed my problem again, at least for the time being. Not sure what could cause this I'm stumped. I hate to keep putting alternators on it every 4 months or so.