Another flicker\pulsing headlight question

[jmann8686]

New here.  first post.  having some headlight issues.  I have a 2013 Silverado 1500 z71.  it is stock as far as the radio goes and electronics.  The only add on I have is a light bar in the bumper and it is wired into my fog lights was there when I bought the truck.  

 

History\back story.  I have owned the truck for a little over a year now.  The voltage drop thing was new to me.  On a road trip I saw my voltage drop.  I didn't look up any info on it I just replaced the alt.  Got a remanufactured one from Orilieys 160 amp. and the voltage was back up above the 14 so I drove for almost another hour.  voltage dropped.  That is when I finally looked into it a read that it was normal so that has never been an issue and I know that my volt meter is suppose to move.  fast forward to about 3 weeks ago I was still no issues with headlights or anything like that I had driven at night a few times and no issues.  After getting home from a hike I jump backed in the truck to go grab some grub.  Truck was sluggish to start but it started. so I knew something was up with the battery/alt.  So Sunday I run down the local Orilieys.  They say I have a bad cell in the battery and that the Diode in the alt is bad.  So that Alt was under warranty so I get another remanufactured alt and a Super Start Premium Battery from them.  Truck started up voltage meter ran like normal.  For the most part It use to drop well below the 14 and now it sits there and only goes up I thought that was weird. But I didn't think anything of it.  Truck ran and started up.  So I tell you all that to get to my issue.  

 

I'm driving down the road one night about 2 weeks ago and I noticed a flicker in the headlight.  Didn't think to much of it.  then the night continues and gets darker and I can really see the  flickering.  sometimes the flicker becomes more of a pulse.  both headlight do it.  I can be do 60MPH  with cruise or without radio on ( but again no sub just stock radio) no heat or AC and my headlights will pulse.  Or I can go from a dead stop and when I push on the gas the headlights pulse.  And now that all this has come to light (pun intended) I notice that the lights flicker a bit at idle. the dome light flicker as well in Park at idle.  it does the pulsing randomly though.  I push on the brakes my headlights dim roll up the windows headlights dim. since noticing this issue I have read a lot of old posts. I have replaced the Alt. with a new not reman 160 amp alt.  I just finished the big 3 tonight.  I used 2 AWG wire on the ground to the block and to the frame.  I couldn't go bigger due to it having to go through the voltage sensor.  I even got a new sensor so that has been replaced.  And I replaced the cable from the alt to the battery with the 2 AWG.  brand new copper crimp rings as well.  Also checked the fuse box under the hood and everything is clean there looks good.  no loose fuses no burnt fuses.  I also replace the 175 amp fuse on the battery.  

 

So after all that I still have the pulsing and flickering.  I have check other random grounds that I could find.  I have cleaned them up and made sure they were tight.  I did notice the ground for the hood to the cab looks like the wire may be broken it is bent at 90 off the hood down to the cab..  I didn't know if that would cause this issue though. and I have not taken off the loom to see if it is bad or not.  I did mess with it and move it around and I still saw my dome light flicker while I was doing it.  I have two thoughts.  Could it be the battery.  I have not had it tested due to it only being a month old and wanting to do the big 3 and check other grounds.  and I have had no starting issues nor issues while driving down.  Or could it be a bad idler pulley cause the belt to slip it was another idea I had.  

 

I have read that is was common on some of these trucks.  My issue is that it only started after the battery and Alt was replaced.  I drive a lot at night so I know that this is a newer issue.  So I don't want to believe it is something I will just have to deal with.  Any ideas or help on this would be great.  sorry for the long post just wanted to make sure I got all the details.  

[dna9656]

This is a pretty tough nut to crack. It's NOT the battery batteries don't cause flicker, batteries get a dead cell, get over charged and the electrolyte (acid) boils out. they can be under charged. I have seen batteries get REALLY (smokin") HOT (over charge) usually due to a bad voltage regulator.

Alternators produce good current at idle, generators did not. When stopped (with a generator) everything dimmed; raise those RPMs and everything brightened up; HOWEVER smaller alternators acted the same way. I had a 35 amp alt. in my 65 suburban acted as prev. described. JC Whitney used to sell an upgrade kit to 70 or 80 amps, worked like a BIG DAWG!

Anyway I digress....

I think you have some kind of unnatural parasitic load (a short) but a bad ground can't be ruled out either no can some sort of relay be ruled out. Bottom line is I think it's in the wiring, not your charging system. The whole lighting system should be checked out, start with the head light and dimmer switches, check any connectors (I'm a big fan of stuffing electrical connectors with Di electric grease to stave off corrosion) related to the lighting system. if you have any added electrically operated equipment on the truck disconnect it and test  the system, see if it's still there or not. There might be a pinched wire in those added lights, if they are wired directly to the fog lights they may be drawing too many amps and some in line circuit breaker is opening and closing (there's your flicker) when the truck has a twist in a turn or some other freaky thing like that.

Usually when freaky stuff happens to your vehicle's electric stuff it's a bad ground, OR some thing is grounding that's not supposed to.

Sorry I don't have an answer but I hope I gave you some ideas; and of what I have run into and maybe some theory you can apply.
I'd like to read about what you find!

Dna

[jmann8686]

11 hours ago, dna9656 said:

start with the head light and dimmer switches, check any connectors 

Could a bad headlight switch cause this.  I looked them up and saw that the headlight switch is the same switch for the fog lights and dome light.  But if that was all bad wouldn't cause my dash lights to flicker as well.  I don't have any flickering going on in my dash lights.  

[shakenfake]

No

[It's Tim]

An oscilloscope will tell if there is AC ripple voltage present.

[jmann8686]

 So that is a no on the switch.  But what about a bad relay.  would that cause an issue.  I pulled the low beam one out and it looks good.  But would that affect the dome light at idle. 

 

Am I back looking for a bad ground.  Could a ground at the back for the tail lights cause an issue like this.   I don't think I have checked the one from the cab to the frame.  Cant seem to locate it.     

 

1 hour ago, It's Tim said:

An oscilloscope will tell if there is AC ripple voltage present.

would a multimeter work.  don't have access to a oscilloscope. 

 

[shakenfake]

https://www.amazon.com/Quimat-Oscilloscope-BNC-Clip-Assembled-Finished/dp/B07QML4LJL/ref=sr_1_14?_encoding=UTF8&c=ts&dchild=1&keywords=Lab+Oscilloscopes&qid=1632338505&s=industrial&sr=1-14&ts_id=393269011

 

Now you do

[Phantom 4D]

Agree that most problems like this are ground related. One thing seems overlooked. Disconnect the light bar and see what happens. Even if you don't use it. My guess is that it's an LED bar, if it's wired into the fog lights, it should have a separate relay. Sometimes these add ons are hack jobs. I've seen it and have had to correct it, if it can be corrected. 

 

[jmann8686]

55 minutes ago, Phantom 4D said:

Agree that most problems like this are ground related. One thing seems overlooked. Disconnect the light bar and see what happens. Even if you don't use it. My guess is that it's an LED bar, if it's wired into the fog lights, it should have a separate relay. Sometimes these add ons are hack jobs. I've seen it and have had to correct it, if it can be corrected. 

 

I disconnected it this morning and will see what that does.  you are correct it is an LED.  But it has its own relay.  It has been on the truck since I have bought it and I have never had this issue until about 3 weeks ago.  I still have it unplugged but I'm not sure how something like that would take a year to mess with my normal headlights.   and of course I don't know if my head lights flicker pulsate when I have my fog lights no due to the light bar over powering them .  But none the less I got it unplugged this morning. and will continue to check things out.
  

[richard wysong]

I assume you have checked the ground from the battery to the body? its possible it got damaged swapping the batteries. maybe try running a redundant ground to the body from the bat

[jmann8686]

29 minutes ago, richard wysong said:

I assume you have checked the ground from the battery to the body? its possible it got damaged swapping the batteries. maybe try running a redundant ground to the body from the bat

I swapped the big 3 last night.  That is why i started this thread.  I was hoping it was a bad ground and when I was done and I didn't even get out of my drive way and my lights strobed I figured it was not those.  Brand new 2 AWG for the ground from the block to the battery and from the frame to the battery.  and from the positive to the alt.  

[jmann8686]

So I went out and looked for more grounds.  Found one more I had not cleaned. I cleaned it up. I’m sure there are more I missed but I can’t find any more. Light bar is unplugged.  I turned on the heat and defrost to make sure I was drawing power. I could rev it up and get the lights to flicker a bit. I push on the brakes lights dim. Fan kicks on headlights almost disappeared.  I can push the brakes a few times headlight pulse a bit.  No matter what I do headlights flicker and it pulse.  So even though the alt is new could it not be working correctly.  Or could it be the battery.  Those are the two things I changed before this all started.  I had no issues before this.  Anybody have any other ideas.  This is driving me crazy. 

[jmann8686]

So this is for the people that look up issues on forums and the OP never posts what the fix was.  So this is for them.  I'm hoping I have the issue solved.  Today I took the truck to the only Napa we have in town cause I was driving by and thought why not have someone else look at it.  Got a pretty knowledgeable guy behind the counter to help me.  He brought the tester out and he hooked up the truck.  fired it up and he scanned the truck.  My brand new alt from Orieliys not reman but new only a week or so old was putting out 15+ volts he had me run the truck for a while to get over the initial start up.  ran the truck with everything turned off including the lights and it was high 14 volts when I turned on the lights including fog light, Radio, and heater the volts jumped to 15 volts and you could see the headlight on the wall flicker pretty bad.  So I ponied up another 175 dollars for an alternator from Napa installed it today.  Did the first test drive and noticed the volt meter went back to acting like it did when I first bought the truck.  It would be a bit above 14 volts for awhile and then after so many miles it would drop and then continue to drop.  it dropped down to around 13 volts. which it did that when I first got it. I had noticed that the last two alternators I got would only drop down to the 14. never any less. thought that was odd.  So waited till dark and went did another 10 mile loop around.  Turned the radio on heat on would play with the windows and nothing headlights just ran like normal.  no flickering of the headlights no strobing. 

 

So for all the people that might be dealing with this issue don't rule out new things from auto parts store. also would not suggest alternators form Orieliys.  My first one was good for about a year.  second and third bad right out of the box.   I did the big 3.  spent a lot of time and money and it ended up being the one of the two things that I changed before all these issues started.  So if your having these issues I would go and have the battery and Alt tested before you start crawling around looking for things.  Just my two cents.   

 

Thank you all who responded.  Hope this treads helps someone in the future.  I know I hate threads that end with the issue not solved.  I just hope this was actually the issue.  Only time will tell.  

[swathdiver]

These trucks electrical and electronic systems do not take kindly to aftermarket parts.

[dna9656]

Used to be alternators put out 13.5 volts I believe, I may have that confused with battery voltage though.... not sure an alternator should be putting out that much... 15Vac.... What about amperage? That's important too. Isn't it possible to put out correct voltage but have an under apm alternator?  It's pretty sneaky for a OEM to spec an alternator or other part that has some sort of covert frequency in it's output or other that would not normally be present in an aftermarket part. I think that kind of game would involve the anti trust laws...