Denali Headlights flicker

[Rbraczyk]

Under normal driving, if you let off the accelerator, the headlights flicker. DOesn't happen all the time, but every so often it'll do it a few times in a row. Seems like its only when you let off the accelerator. Just nervous that something else will go wrong.

[Rbraczyk]

the voltage drops down about two points as well. ANyone gonna help or do i have to wait for the warranty to expire first?

[Vroom2]

What year Denali are you running? This is a known issue, unfortunately without a fix, for all model years that have the Stabilitrak system. I get the same thing on both of our trucks. The cause is the traction control's drain on the electrical system - which applies whether or not you disable it.

It's bugged me since day one!

Take care,
Jerry

[rzkz8k]

Jerry, Do you see this condition on your 2004? You should not because the 04 MY, they starting using the power steering system preasure for breaking.

[Vroom2]

Ahhh....that explains it! I noticed the problem has disappeared on the '04, but didn't understand why. How did they tie in the two systems, do you know?

Take care,
Jerry

[Rbraczyk]

its an 02 and it only happens when the a/c is on. Sry bout not providing specifics, been busy with school.

[rzkz8k]

Originally Posted by Vroom2

Ahhh....that explains it! I noticed the problem has disappeared on the '04, but didn't understand why. How did they tie in the two systems, do you know?

Take care,
Jerry

The way I understand it is the ABS/VSES (AKA: Stabilitrak) system uses the hydraulic preasure from the power steering system (HydroBoost) to manage control of the brakes instead of generating preasure from an electric motor.

[Rbraczyk]

We have a loud squealing noise from the motor, most likely the a/c bearing.

[tonytone]

Originally Posted by rzkz8k

Jerry, Do you see this condition on your 2004? You should not because the 04 MY, they starting using the power steering system preasure for breaking.

Ha ha...now instead of the headlights flickering, your power steering will start chattering when Stabilitrak comes on! j/k

[Rbraczyk]

Is anyone going to reply to me or are you guys gonna start a chatroom in here?

[Vroom2]

Sorry - we did get carried away there. Have you ruled out the alternator? Could the squealing noise you hear be the bearing?

Take care,
Jerry

[tonytone]

A quick and dirty way to find out if it's the alternator--with the engine running, disconnect both battery terminals and measure the voltage across the two disconnected wires; if it's less than approx 13.6 V (I think that that was the correct figure but I could be wrong), then your alternator is not putting out enough juice to charge the battery, and if it's even lower than that, it's probably working really hard just to supply enough juice to keep your truck and other electrical accessories running adequetely. Could also be a voltage regulator issue but some of them are integrated into the alternator so even if it's bad, you'd still have to replace the entire alternator; if the VR is separate from the alternator, you could just replace it but odds are that even if the VR is bad, the alternator will soon follow anyway since a bad VR could cause the alternator to overwork itself as far as charging is concerned, thus shortening its life even more...if any of that makes sense, which it probably doesn't...I dunno...

Actually, if--with the engine running--you disconnect the battery terminals and the engine cuts out right afterwards? Then it's almost definitely the VR and/or the alternator is bad.

[Rbraczyk]

Like i said, it only happens when the a/c comes on, and we've ruled out the alternator.