[MtnTallPaul]

Put new batteries in tonight - details in another thread.

But still having issue with pulsing lights as shown in this video.

Video shot idling in the driveway, but things look similar while driving.

What do y'all think?

 

[Hydro]

Does this continue after the glow plugs have stopped cycling ?

Factory alternator ?

 

[MtnTallPaul]

Does this continue after the glow plugs have stopped cycling ?

Factory alternator ?

Yes, continues after glow plugs have stopped, and visible in headlights while driving.

As for the alternator, I don't know. It has the alternator that was on it when I bought it with about 150K miles.

I installed new batteries today, but it did the same thing with the old batteries.

 

[Hydro]

Check the plug on the back of the alternator -- if the voltage sense wire is loose in the connector, it can make this happen

you can also jump that wire for a test to see if the lights stabilize
hmm, can't remember if the Ford alt will keep charging with that plug disconnected or not -- some will
pull the plug off the alt with the engine running -- connect your meter to the battery or alt output post while you do this to see if the alt continues to charge
Anyways, this will eliminate the truck wiring for , sense and charge light

 

[Bjet]

I know ive had bad alternators make my radio do that in trucks before, but never noticed the lights.

 

[mlgjellybean123]

I'm gonna be real with you, I don't see the pulsing lights. Are we looking at the monitor? I can kinda see it there, but otherwise, I'm not seeing it lol

But anyways, might be time for an alternator upgrade if the wiring checks out

 

[bismic]

How are you determining that it is after the glow plugs go out?

You do know that the glow plug light is not "connected" to glow plug operation - correct?

 

[TooManyToys]

It would not be a battery issue; loose connection/alternator/GPCM.

 

[Hydro]

Had a charge issue like this once, with the flickering and unstable voltage
alternator was losing ground
mounting bolts were tight, but there was oxidation on the surfaces and was insulating the frame of the alternator from the block
I had discounted this as a problem and was searching other places
turned all the accessories and lights on to make a load -- and seen a slight glow at one of the mounting bolts
Weird stuff happens

 

[MtnTallPaul]

How are you determining that it is after the glow plugs go out?

You do know that the glow plug light is not "connected" to glow plug operation - correct?

This was several minutes after startup, well after glow plugs would shut off.

 

[bismic]

The glow plugs can run for up to two minutes (if something goes wrong with that operation and it doesn't shut off, I believe the PCM will get involved at the 3 minute mark). I just posted what I did because way too many folks think that the glow plugs go out when the light goes off, and I wasn't sure if you already knew that.

I agree, in two minutes in mild(ish) conditions (temperatures) they were probably off, but you should look at system voltage to determine if they are actually off. Even better would be to measure and watch amps from the GPCM. All that is said because you could have issues with the GPCM itself that could cause extended operation when unexpected.

I'm not one to idle a lot in the mornings *partially because the temperatures are mild here). That said, In the first start of the morning, I don't like to move until the voltage rises to where it should run - indicating the glow plugs are off.

Just throwing out possibilities that might be inexpensive and easy to resolve.

 

[MtnTallPaul]

The glow plugs can run for up to two minutes (if something goes wrong with that operation and it doesn't shut off, I believe the PCM will get involved at the 3 minute mark). I just posted what I did because way too many folks think that the glow plugs go out when the light goes off, and I wasn't sure if you already knew that.

I agree, in two minutes in mild(ish) conditions (temperatures) they were probably off, but you should look at system voltage to determine if they are actually off. Even better would be to measure and watch amps from the GPCM. All that is said because you could have issues with the GPCM itself that could cause extended operation when unexpected.

I'm not one to idle a lot in the mornings *partially because the temperatures are mild here). That said, In the first start of the morning, I don't like to move until the voltage rises to where it should run - indicating the glow plugs are off.

Just throwing out possibilities that might be inexpensive and easy to resolve.

Thanks for the response.

Yep, I am aware the glow plugs remain on after the WTS light goes out.

Yes, I confirmed with system voltage that the glow plugs were off. Didn't really need to, as I have noticed this issue after driving home which is about a 30 minute trip.

I'm with you on waiting until the glow plugs are off.

 

[Hydro]

Checked the plug on the back of the alternator yet ?

 

[ChrisSki]

If you have a multimeter, what is the AC voltage between the positive terminal and a grounding point on the truck? AC jitter can do strange things.

 

[Alaskanfun]

Is your alternator light on? Like this one?

 

[MtnTallPaul]

Is your alternator light on? Like this one?


View attachment 789333

Nope.

Not the one on the dash or the pictured one under the hood. 🤪

 

[MtnTallPaul]

If you have a multimeter, what is the AC voltage between the positive terminal and a grounding point on the truck? AC jitter can do strange things.

I will do that next time I have a chance, as well as inspecting the connections on the alternator as suggested by someone else here.

Sorry I can't credit that person - I have slept since then. 😛