Lights pulse or flicker when accelerating

6112 Views 6 Replies 5 Participants Last post by christopherfranks252, 2 mo ago

headrocker07

Discussion Starter · Mar 21, 2019 (Edited)

2016 Impala Limited LT 3.6 V6 70k miles
When I'm accelerating, my headlights (and I assume taillights as well) pulsate. The overhead dome light is also affected. Dash lights do not pulsate. This all started happening after I had an alternator and battery go out on me, leaving me with a dead car. Warranty covered a replacement of both. Since then I notice the problem when I merge onto highways or press the gas more than 10%. In park, if I rev the engine to around 1.5k or 2k rpm, I notice the interior dome light doing the same thing. When the car is idling, there is no pulsing that is enough to cause concern.

I have a dash camera running through my OBD port with an adapter. I had it installed after my window was broken. I had a car audio shop install a 10" powered Sub/Amp. The camera was on my car since before my alternator and battery went out, the audio equipment was installed after new alternator and battery.

I turned off all accessories, pulled the fuse on my amp, unplugged my camera, and still I notice a pulsing when I rev over 1500 rpm. I noticed I could force the lights to stop pulsing if I act like I/m rolling my windows up.

I work at a GM dealership, and I've asked around my shop, and none of the technicians have any other ideas.

Am I putting too much load on my alternator? Do I need a bigger battery than stock?

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jtrosky

· #2 · Mar 21, 2019

Almost sounds like vibrations causing the issue - as in when the motors revs enough, it increases vibrations and is maybe causing a loose connection to become "intermittent"...

Just something to consider... Usually, flickering lights occur more at idle than at higher RPMs (when dealing with lack of power) - as more RPMs allow the alternator to generate more power.

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headrocker07

Discussion Starter · #3 · Mar 23, 2019

It could be but remember, i can fool the car somehow by using my window switches while the pulsing happens. It goes away until i stop using a window switch.

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headrocker07

Discussion Starter · #4 · Sep 26, 2019

Figured I give an update and solution after all this time.
Seems as though my replacement alternator was junk. New battery and alternator under warranty fixed the issue. As a side note, working at a GM shop has taught me that this happens more than you think. So don't rule it out.

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plano-doug

· #5 · Sep 26, 2019

headrocker07 said:
Figured I give an update and solution after all this time.
Seems as though my replacement alternator was junk. New battery and alternator under warranty fixed the issue. As a side note, working at a GM shop has taught me that this happens more than you think. So don't rule it out.

I got two bad remans in a row from Western Auto years ago.
...
I was told once that all that was done at alternator reman shops was to find one bad part, replace it, paint the housing, and box it up. I'd like to think some basic testing was done before boxing it, but I wonder.
...
I had a customer in the central US who was buying voltage regulators from us. These chips were intended for automotive applications. It's been a while, but, as I recall, the spec sheet required the user to take a measurement during assembly, and apply a pair of resistors to the circuit. The resistor values came from a table with 5 entries, with the measurement result used to select which of those 5 pairs. (I know, it sounds kind of kludgy; that's what I thought 20 years ago when I first read it.)

Anyway, this customer, who was in the alternator reman business, wanted to only stock 2 pairs of resistors instead of 5, so he wanted a spec from us that simplified the selection down to 1 of 2 instead of 1 of 5. Using this would mean that about 60% of the time, the alternators would be out of spec.

I begged off from helping the guy. And I'm still shaking my head over that one. :dizzy:

Doug

.

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sheila

· #6 · Sep 26, 2019

^ Ye 'ol "rattle can reman", lol!

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christopherfranks252

· #7 · 2 mo ago

headrocker07 said:
2016 Impala Limited LT 3.6 V6 70k miles When I'm accelerating, my headlights (and I assume taillights as well) pulsate. The overhead dome light is also affected. Dash lights do not pulsate. This all started happening after I had an alternator and battery go out on me, leaving me with a dead car. Warranty covered a replacement of both. Since then I notice the problem when I merge onto highways or press the gas more than 10%. In park, if I rev the engine to around 1.5k or 2k rpm, I notice the interior dome light doing the same thing. When the car is idling, there is no pulsing that is enough to cause concern. I have a dash camera running through my OBD port with an adapter. I had it installed after my window was broken. I had a car audio shop install a 10" powered Sub/Amp. The camera was on my car since before my alternator and battery went out, the audio equipment was installed after new alternator and battery. I turned off all accessories, pulled the fuse on my amp, unplugged my camera, and still I notice a pulsing when I rev over 1500 rpm. I noticed I could force the lights to stop pulsing if I act like I/m rolling my windows up. I work at a GM dealership, and I've asked around my shop, and none of the technicians have any other ideas. Am I putting too much load on my alternator? Do I need a bigger battery than stock?

Mine just had this issue thought i would need a new battery but turns out 3 of 6 elements were burned out even tho it was still firing it was causing a power issue because the engine wasnt working full blast because of reduced spark new plugs and new wires it works like new no flickering i originally thought it was battery or alternator replaced battery with one i had and tested alternator the alternator was good so couldnt figure it out till i did my tune up works great now besides not being able to fill gas

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