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Discussion Starter #1
Hi all,

I had to have my alternator replaced about a month ago. (On my hour long drive home from work, I watched my battery voltage drop all the way down to 9V, right before my entire dash went black and I lost power steering as I was 1/4 mile away from home). I charged up the battery overnight and was able to drive it to PepBoys the following morning (was down to 11v) as I pulled into PepBoys.

They replaced the alternator. However, I immediately noticed the following morning that my headlights were flickering. Since, I was still on my original OEM Battery (4 years, 100K miles), I went ahead and replaced the battery myself. Still flickering headlights...

Fast forward to this past weekend, I got the truck back into PepBoys and they said they found the alternator faulty and replaced it with another brand. However, this morning, I see the lights are still flickering.

Any ideas what else could be causing this?

Thanks,

Jeff
 

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Some ground not secured? check all connections to make sure they're snug. I can't tell you how many times Ive found a detail that wasn't finished properly. Sometimes my own!
 

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Yea, I know. when I was someone who took phone calls to fix ppls problems, it was often the most simple of things.
BTW, if you call a computer help line and the rep say, "let's try this", hang up and call back until you get that person who knows what to do. You won't hear the word "try" from them.
 

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Discussion Starter #6
Not that this proves anything one way or the other, but the flickering does not happen when the engine is not running... I also see the flickering with the interior dome lights as well.

How many connections are there from the Alternator to the battery (that an Alternator replacement would have involved touching)?

Since, they've replaced the alternator twice, I would have imagined they would have found/corrected a loose ground at the Alternator side the 2nd time. I replaced the battery myself and the ground was very tight there on the original battery.

I'm going to take it back to PepBoys regardless, as I don't want to end up paying for something somewhere else that PepBoys should have been able to diagnose correctly...
 

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In the future I'd suggest finding a small shop. I've admittedly been lucky finding good ones, but I think you get a lot more stability in personnel at small shops and thus more consistency. I would consider going to Pep Boys, Goodyear or even a dealer somewhat of a crap shoot (the dealer having the advantage of only dealing with a single brand).

Of course there are bad small shops too. I've told the story of my SIL's Explorer where the small shop near his apartment was quoting $3,000 of suspension and brake work for what was obviously a drive-train issue. That place is now out of business! And I had bad luck at a transmission shop (should have gone to my small shop, but I knew they contracted transmission work out so I figured why not deal with a transmission place myself). But once you find one that does good work that knowledge will be invaluable and save you a lot of time and money in the future.
 

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I worry about any aftermarket electrical components from the auto parts stores. Too many issues over the past. If it’s not AC Delco or GM, NEW, I do not buy it. I go to Autozone sometimes to pick up misc. items and I cringe when I am in line waiting to pay and hear someone next to me, buying an alternator or starter. If they just knew.
 

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I worry about any aftermarket electrical components from the auto parts stores. Too many issues over the past. If it’s not AC Delco or GM, NEW, I do not buy it. I go to Autozone sometimes to pick up misc. items and I cringe when I am in line waiting to pay and hear someone next to me, buying an alternator or starter. If they just knew.
I think I need to start following that advice more often, but that's because I'm getting older and doing less myself. For me it has depended on how difficult it is to replace. I put a NAPA alternator in my 89 Ranger at 107,000 miles, replacing the original, and it's still going 95,000 miles later. It's right on top though and easy to change out. Other vehicles I'd pay someone to do it, so that makes paying for a better unit a better bet.
 

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Never had any dealings with NAPA, so I cannot comment on them, just a firm believer in AC Delco and GM, Toyota, etc. I stay away from aftermarket, unless that’s all there is available.
 

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Never had any dealings with NAPA, so I cannot comment on them, just a firm believer in AC Delco and GM, Toyota, etc. I stay away from aftermarket, unless that’s all there is available.
I'm not disagreeing with you. I only mentioned Napa because that's what I had in my service notes. My main point was on that vehicle it's so easy having to replace again isn't a huge deal. I'd rather do that than change the plugs. Two of those are difficult to get to.
 

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We got stranded in my buddies 1/2 ton Chevy in western kansas on a Saturday at midnight(heading home from an elk hunt) Alternator caught fire, I put it out with my Dt. Mt Dew... buddy said that is his 4th one he has had replaced.He waas not sure iif they weere rebuilt or just aftermarket ones.. Tow truck guy had a parts store, with Delco Alternators, almost 8 years later it was still in the truck..
 

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Discussion Starter #13
Unfortunately, it was a Friday evening. I called the closest dealer, but they couldn't get me in until Monday. I didn't have enough battery to drive any farther. So... PepBoys it was...

Additional info: I put my multi-meter on the battery with the engine running. Voltage was bouncing all over the place between 13v and 14v. Is that normal?
 

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Having never seen your vehicle, let alone take any measurements I really shouldn't type anything. Problem is - I'm not wired like that.

I doubt any connections are loose. The alternator has been replaced twice. People don't tend to do more work than they have to. Likely the connections at the alternator and battery ground are all that have been messed with. Twice.

Do you see a small 2-wire connector on the back of the alternator? My diesel has one. It is used to raise/lower output voltage and resulting current as a function of throttle/brake input. It helps save a little fuel by bumping up charge current while coasting or braking. That's lost energy - might as well stuff it in the battery.

If you have that connector, depress the latch and unplug it. You will get a charge system error but we don't care for now. The alternator will default to locally sensed constant voltage regulation. If the headlight flicker goes away the aftermarket alternator was incorrectly reverse engineered and either needs to go back or you get used to flickering lights. This would indicate a classic control instability. Basically the alternators response time for a control input is is different than the chassis controller expects.

It's just one test. If it finds a problem you've located the issue, else it's something else. My un-edumacated guess is incompletely reverse engineered control strategy. FWIW the old electro-mechanical solenoid regulators for generators (remember those?) all pulsed. Control theory was not addressed at all and that's just what ya got. Such is the case with my brother in law's old 912. Cool car. he's owned it over 50 years.
 

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'Nuther thought...

Sampling two different aftermarket brands may not indicate much. Brands are generally marketing/distribution facades. How many Chinese factories are needed to manufacture one device?
 

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Suggesting a ground fix on a Colorado/Canyon (or most any vehicles) is the equivalent of asking "Have you turned it off and on again?" (IT Crowd reference)
The best series on the telly right there!!!
 

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Not that this proves anything one way or the other, but the flickering does not happen when the engine is not running... I also see the flickering with the interior dome lights as well.

How many connections are there from the Alternator to the battery (that an Alternator replacement would have involved touching)?

Since, they've replaced the alternator twice, I would have imagined they would have found/corrected a loose ground at the Alternator side the 2nd time. I replaced the battery myself and the ground was very tight there on the original battery.

I'm going to take it back to PepBoys regardless, as I don't want to end up paying for something somewhere else that PepBoys should have been able to diagnose correctly...
My gut and heart say no, but I'm wondering if you have a connection problem to/with the ECM, being it controls the charging on our trucks. It would be odd that 2 of them where bad in the same way but odd things do happen all the time. I'm going to guess and hope Pep Boys will get another one from a different supplier this time and you will know (almost) for sure if that's it.
Please let us know what you find!
 

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You really need to find out what outside source they are getting their parts from, then you can look it up yourself and maybe find out the quality of the alternator, and reviews. Pretty sure that Pep Boys does not stock alternators, may be wrong. That would be a huge inventory tie up.
 

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You really need to find out what outside source they are getting their parts from, then you can look it up yourself and maybe find out the quality of the alternator, and reviews. Pretty sure that Pep Boys does not stock alternators, may be wrong. That would be a huge inventory tie up.
Not sure how stocking of alternators is done, but I know when I went to Autozone on a 2000 Mitz-bitch Montero of daughters, they tested it and then had a couple of options for alternators on the shelf of different quality levels, I assume. As I was buying and I knew this vehicle was not long for the roadways, I purchased the cheapest. It lasted longer than the Montero.

I think that certain parts like alternators are pretty standard, at least across a manufacturer. But then, I am not sure how much Pep Boys stocks. Here in the Fort Worth area, Autozone has a lot of stores, but there is a store over in Haltom City that is where they stock most of the parts. If they don't have it at a satellite store, typically they transfer it over from that store or you can run over to there to pick it up.

Back in the 1980s, my uncle used to work on all the neighbors' cars. I was living in same town, and didn't know anyone, so when my alternator on my Ford died on a Saturday morning, I called him to find out where could I get an alternator before the parts houses closed at noon. He had me come by his house, where he had a Ford, a CHrysler and a GM alternator on his shelves that he had rebuilt. We swapped them out, and then broke down my alternator to see what was wrong. Turned out the brushes were worn, he replaced the brushes and bearings, and 2 weeks later bragged to me he had it on his Econoline van because it had a higher output than the original one.
 
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