flickering lights

[chcknugget]

I know I saw a thread on this not too long ago, but I can not find it.

Basically my lights (especially my dome light) always flickers when the car is on. When I tap the brakes all my lights dim and my headlights actually turn off for a split second. My voltage guage does't move much.

Any suggestions?

[BlazerLT]

What is your voltage gauge reading when this happens?

[chcknugget]

It always runs at 14v.

Except for when I push the electric window up button and the window is already up the voltage drops to ~11-12 volts.

[wolfox]

I am thinking weak/failing regulator. Had something similar happen on my Subaru when the regs started to die. It would charge up just fine, after a long while. There are three "power cycles" per revolution of an alternator. If you are down to just two, or one bank of regulators or windings in the alt; impulse currents, especially when your A/C clutch pulls in will "spike" the lights. The gagues are notoriously inaccurate - so double check your truck's charging voltage at idle, acessories off at the battery with a Voltmeter.

If everything's tight and doing what it should, you should be reading about 14.8 volts steady, with little dip when your headlights are off, no power accessories running, etc. If it reads lower than 14 volts at idle with a known, good volt-ohm meter, start shopping for a new alt. It's not an emergency - yet. It's a cascading failure because the remaining good windings and regulators have to work harder to make up the juice that is just not there from the missing phases in the alternator. Good luck - and always check with a bench meter when in doubt.

EDIT: Parting thoughts - Oh, and of course, clean and tighten all cable ends and battery terminals. And this is going to sound odd, but also get underneath if you can and clean, retighten block ground straps, and brush starter motor terminals clean. Alot of juice flies around through these key areas and may affect charging and power throughout the vehicle.

[BlazerLT]

Yip, sounds like a weak alternator.

[chcknugget]

Will check that with my multimeter tomorrow.

I also remember reading something about poor grounding. Are there some grounding or power wires that just should be replaced?

[wolfox]

The one on the battery ties just about right to your block. Clean not just the battery end, but follow it back to the block where it bolts on. Torque off the bolt, and hit it with your favorite wire brush. (Both sides, and where it meets the bolt) There are numerous body grounds to chase too, but I would only go after those if a particular accessory was giving me fits. Covering your basics here should help you out some. The cheap and dirty fix is to just clean stuff and careful observation. If after cleaning, and you still cannot touch a hearty 14 Volts, I would start checking out the local parts shop and pricing around for that alt.

[BlazerLT]

Maybe make sure the positive cable going to the alternator is nice and tight.

[wolfox]

D-oh, good point! There is a harness that plugs into the back of the alternator that disappears into the same loom that your fat battery cable on the positive side follows in paralell to the battery terminal. I hear, but have yet to see one of these get so rotten as to cause poor charging. Now that I think about it - I have yet to even look at mine! Eh, tomorrow's another day... I am already up too late.

[BlazayBlazerious]

[quote=chcknugget]I know I saw a thread on this not too long ago, but I can not find it.

That was my post about a month ago. I just got it fixed. It was the voltage regulator. Same exact symtoms. The gear selector and the odometer flicker like they are candle powered. You step on the brakes and the headlights go off for a split second. Too funny about pushing the window button up! I noticed the same thing. It sounds like its new alternator time.

[chcknugget]

i replaced a "new" remanufactured alternator a year ago... Can I buy just the voltage regulator? Or is it more reasonable to just buy a new alternator?

[wolfox]

Weighing the hassle and time of yanking an alternator, pulling it apart and rebuilding it - then dropping it back in

VS.

Yanking an alternator, turning it in for the core charge on a rebuilt/new and putting it back in...

It's worth my time and money to get the outright, complete replacement. That way I am not rolling the dice on bearings, windings, armatures or commutator collars. Screw that man - leave the nit-picky stuff to the folks that rebuild the things for a living.

[chcknugget]

It seems that online "performance" alternators are just as expensive as return- autozone remanufactured ones (about 65 bucks). What would you suggest?

[wolfox]

Cannot go wrong with a Duralast Gold - they are factory new, just carry an Autozone sticker on them. Upgrading to a beefier "performance" (150 amp) alternator requires a bit more work. You will need to crimp on a whole new harness and run a thicker charge cable. It's all a matter of need and preference. I do not run big radios, or alot of accessories in mine. So a plain old "as new" and not "rebuilt" Duralast does me fine. (Costs about $98 instead of $60 or so) I am already saving against the cost of repair/replacement because the one under the hood is a Delphi rebuilt - it's already eaten an alternator in it's lifetime before I bought it I think.

[chcknugget]

I wasn't really looking into a 150A alternator, just a non-stock one. As I said, the reman I had is only a year old. I have an amplifier in the back, but have no "power capacitor". I've heard that these help increase alternators life span. In my opinion I don't run my speakers heavy at all, but do you think that these are a good investment?