2012 Yukon headlights flicker on acceleration

[i6pwr]

All was working fine until my OE alternator went bad. I did rinse off the engine bay as I have done numerous times,with always being careful not to hose down the alternator.

Within a day of the last rinse, may or not be coincidental, I received the battery light on the dash and could see it wasn't being charged.

I replaced the alternator and I then noticed my headlight would flicker with varying intensity of light output when accelerating at about half throttle.

I checked all the connections, alternator signal connector, battery terminals, ground wire, all was clean and tight.

I chalked it up as a faulty alternator since the voltage would jump to 15V when the lights would flicker.

Replaced alternator and it did the same, both were from Autozone. I returned that one and went with NAPA. Same thing with the NAPA, so I'm keeping this one till I figure it out.

I unplugged the load shedding connector on the NEG cable with no change.

Doesn't happen on light acceleration, only strong, half-throttle or more, also when downshifting on accel.

The battery is maybe 1YO, and secured, no loose wires.

Here's a video of the Torque App, happens at beginning and around the 1 min mark, tried to include accel, cruise, slowing in the clip.

Can't seem to find the culprit, and has to be annoying to people in front of me as it looks like I'm flashing my lights.

 

[atikovi]

Check for codes in the BCM and ECM. I bet the flickering is from the voltage regulator cutting the power when the voltage goes too high. Most all chain store alternators are junk btw.

 

[i6pwr]

I'll double check but I had the Tech 2 on it last week and I didn't see any codes.

Hard to imagine all 3 alternators are bad....but I agree some aftermarket electronics are junk.

 

[mrbreezeet1]

Check for codes in the BCM and ECM. I bet the flickering is from the voltage regulator cutting the power when the voltage goes too high. Most all chain store alternators are junk btw.

What about A/C ripple, might need a lab scope to check it though?

 

[mrbreezeet1]

I'll double check but I had the Tech 2 on it last week and I didn't see any codes.

Hard to imagine all 3 alternators are bad....but I agree some aftermarket electronics are junk.

Don't get me started!

 

[mrbreezeet1]

How do you make a real time Video of torque app like that?

 

[i6pwr]

What about A/C ripple, might need a lab scope to check it though?

I have a Rigol scope I could use, if you can analyze the waveform...not sure what would be good or bad.

How do you make a real time Video of torque app like that?

AZ screen recorder.

You can record with or without audio, interface takes some practice...edit out the unwanted screens before and after the clip.

 

[mrbreezeet1]

AZ screen recorder.

You can record with or without audio, interface takes some practice...edit out the unwanted screens before and after the clip.

I'll have to check it out.

I have a Rigol scope I could use, if you can analyze the waveform...not sure what would be good or bad.

I never used one too much, I'm sure we could find info online though!
Let me know if you want me to research it a little, when l get my car done though.
Obviously, A/C would be a ripple wave and D/C would be square wave.
That's all I got so far.

 

[KrisZ]

That last minute or so with the voltage jumping like that tells me something is wrong with the voltage regulator.

 

[b_b]

hate to tell you, but the only way to rule out alternator is to buy the expensive one from the dealership. had a similar experience with an accord. alternator went out and the auto parts store alternator went out in six months. had to do go to the dealer and pay for the expensive one and do the job twice.

 

[Marcozi]

You can us a digital volt meter to check for AC on the DC voltage. Just set the meter to "AC" and see what it reads. A friend of mine with a pristine 30 year old 300Z was having electrical issues. The DC voltage was varying badly. I then checked theAC on the DC voltage. Yikes! He had the alternator replaced.

 

[mrbreezeet1]

All was working fine until my OE alternator went bad. I did rinse off the engine bay as I have done numerous times,with always being careful not to hose down the alternator.

Within a day of the last rinse, may or not be coincidental, I received the battery light on the dash and could see it wasn't being charged.

I replaced the alternator and I then noticed my headlight would flicker with varying intensity of light output when accelerating at about half throttle.

I checked all the connections, alternator signal connector, battery terminals, ground wire, all was clean and tight.

I chalked it up as a faulty alternator since the voltage would jump to 15V when the lights would flicker.

Replaced alternator and it did the same, both were from Autozone. I returned that one and went with NAPA. Same thing with the NAPA, so I'm keeping this one till I figure it out.

I unplugged the load shedding connector on the NEG cable with no change.

Doesn't happen on light acceleration, only strong, half-throttle or more, also when downshifting on accel.

The battery is maybe 1YO, and secured, no loose wires.

Here's a video of the Torque App, happens at beginning and around the 1 min mark, tried to include accel, cruise, slowing in the clip.

Can't seem to find the culprit, and has to be annoying to people in front of me as it looks like I'm flashing my lights.

Where are you located at? I know A real good old fashion rebuilder in Wheeling WV!

 

[mrbreezeet1]

hate to tell you, but the only way to rule out alternator is to buy the expensive one from the dealership. had a similar experience with an accord. alternator went out and the auto parts store alternator went out in six months. had to do go to the dealer and pay for the expensive one and do the job twice.

My Advance Auto one was basically bad out of the box! Took it RIGHT BACK and put bearings and brushes in my old one and I was back on the road again!

 

[i6pwr]

That last minute or so with the voltage jumping like that tells me something is wrong with the voltage regulator.

I agree, and cannot think of anything else, unless the voltage regulator is outside the alternator on this platform...but all 3 alternators?? Maybe so.

This was the most recent drive cycle, I used both the OBD and Command Module voltage displays, OBD on left but they generally follow each other.


Only happens on a good load, maybe 1/2 throttle or more.

hate to tell you, but the only way to rule out alternator is to buy the expensive one from the dealership. had a similar experience with an accord. alternator went out and the auto parts store alternator went out in six months. had to do go to the dealer and pay for the expensive one and do the job twice.

Yeah, I think it may come to that.

You can us a digital volt meter to check for AC on the DC voltage. Just set the meter to "AC" and see what it reads. A friend of mine with a pristine 30 year old 300Z was having electrical issues. The DC voltage was varying badly. I then checked theAC on the DC voltage. Yikes! He had the alternator replaced.

I was able to get a few voltage spikes on the Torque App when power breaking it, not as frequent compared to driving, but the same flickering nonetheless.

This is the current alternator during power braking, seems to ripple quite high at about the same frequency.

300+ mV is pretty high.

 

[mrbreezeet1]

"unless the voltage regulator is outside the alternator on this platform..."

I'm 99% sure the V.R. is inside the Alternator on that platform.

 

[i6pwr]

I have an OE AC Delco alternator on order, will update once installed.

 

[i6pwr]

The box of OE goodness arrived today...

Eye candy and documenting authenticity.

To recap, I lightly sprayed the engine bay, being careful not to soak the PCM or alternator, I usually place a bag over the alternator but this time I was just unlucky.

I lost the alternator after about 10 miles then replaced with a reman from Autozone, then a new one from same place, both exhibited flickering, returned the 2nd one and went with a new one from NAPA, same deal, all 3 acted the same and made me think it was something else.

Today I installed the OE AC Delco from Rock Auto....not a hint of a flicker after 30 miles.

I don't want to void the warranty on the old one but I'm very curious to see what electronics are inside.

 

[KrisZ]

There aren’t any super complicated electronic pieces in these. There is a diode set to convert AC to DC current and a voltage regulator. But cheap remans can’t even get these correctly, hence your issues.

 

[b_b]

told you, things have become to complex and electronic to sensitive for aftermarket companies to make the same quality product at the lower price. they get the price lower by lower standards and assembly methods.

 

[dogememe]

Glad you got it figured out but sad the aftermarket failed you. Should be so simple.

if anyone goes aftermarket on their alternator try to get a NEW one. They aren’t perfect but last way longer and are rarely bad out of the box.