kryptonTJM

I drive a 2007 gt. For the past few years I've noticed that the headlights flicker when I'm idling or at a stoplight. Also when I turn the dome/map lights on, they flicker as well.

there has been no other issues with the car. No dead battery or anything.

the alternator was changed in late 2014 and the battery was replaced in early 2015.

like I said, no issues with the car, or anything. What could be causing this?

Jazzman442

If the lights are blinking it is either a bad ground ( not likely by the description ) or the Alternator is bad It is send some ac out. The battery is like a buffer for this. Is there any noise in the am radio? Does it stop when you rev is up? Did you check the out put of the alternator?

kryptonTJM

no there is no noise in the radio. The battery meter on the gauge cluster hasn't moved either. From what I've noticed, it doesn't stop when I rev up. Like I said, it's been do I g this since 2014 with no issues in performance. AutoZone even tested the alternator and everything was good. A friend of mine said it could be a ground or loose connections due to vibration.

Jazzman442

If a volt meter is not fluctuating on the battery when the lights are flickering Well than you have a ghost. So it is just the lights. Do the lights in the radio blink??

Cavero

If I remember right, the battery meter is an idiot gauge, it just tells you "good" or varying degrees of "bad", it's not a live gauge that'd show you all the little variations. It'd be better to datalog or test it with a real voltmeter.

Since 2014...before or after the new alternator went in? Its possible you have a bad diode in the rectifier, or a bad ground like Jazzman said. The autozone tests aren't good at detecting a bad diode.

kryptonTJM

No, the radio lights do not blink. Neither do the dash lights.

kryptonTJM

I just got back from the dealer. They said It was the alternator. How could it be bad already? It was replaced in 2014 and it's from autozone

SpectreH

The Autozone alternator might have been a cheap Chinese knockoff.

kryptonTJM

the ford dealership is putting a new one in tomorrow. It's going to cost 325. I don't see how it lasted 3 years without going out completely.

I love my car, but sometimes I wish it had a face so that I could punch it

Cavero

When my alternator died last year I read a lot of threads about the AutoZone ones being crap. Since you're paying for Motorcraft parts, see if the dealer can put in an alternator from a 2010. The 3-phase alternators are supposed to be a lot more reliable than the single phase that the 2005 - 2009 had

Cavero

You can skip to post #9
https://themustangsource.com/forums/f637/p0622-code-charging-system-datalog-539499/

07 Boss

I had ford put a new alternator in a few times but once they put one in and it died the next day.

Here is the real issue. It is hard to find actual new alternators because nobody wants to make these POS single phase alternators. You might be able to find some from Ford but I can almost guarantee that any from the chain parts stores are going to be rebuilt/re-manufactured units. After going through a number of these I switched to a new 2010 alternator.

Jazzman442

Most if not all rebuilds or new Cheap alternators have Chinese Diodes. They make a ton of noise and blow out quick. One thing to never buy aftermarket especially from AutoZone is an Alternator. I just cant stand the noise of them.

Clapper

Just got a 2007 V6 and the alternator looked new but was only putting out 12.7 V so I swapped it for a Reman Ultima 135 Amp Alternator from O'Reilly. After install alternator was putting out steady 13.7 V. Battery tested good. Alternator died (today) after three days while driving and barely got home on battery. Headlights have flickered since I got the car and that seems related.

I don't think that the headlight switch is bad because new led driving lights also flicker same and they are wired to an accessory fuse with no switch. The flicker may be a little affected by RPMs but flicker is pretty steady at idle or speed. I have checked and tightened engine to chassis, chassi to battery grounds. I replaced the three wire pigtail on the alternator and put in another warrantied Ultima 135 Amp Alternator from O'Reilly. For all I know they all come with bad diodes, but who knows. Added a 4g ground from alternator to battery just to be safe this time. Detected a very small voltage there before grounding. Checked resistance between all points (alternator, block, battery) and no resistance found. Engine to chassis ground is tight and good. Headlights still flicker.

I am thinking next step is plugs and plug wires, but I am going to wait a week to see if the new alternator gets killed first.

I have read this and all the other threads out there on Mustang flickering headlights and alternator problems and there are a lot of guesses and lectures about Chinese parts etc. and that is not much help. Also the "Well I have no idea but try . . ." sort of responses are no help. I am already in spend mode getting nowhere fast trying to troubleshoot logically.

What I really want to know is (1) whether anyone has actual knowledge of anyone ever actually solving the flickering headlight issue? or (2) solving the car killing the alternators issue?

From what I have read over the past three days, not one person has nailed this at a dealership or otherwise despite the problem being very common with these cars. God, I hate electrical problems.

07 Boss

Sorry, can't help you with the lights, I've had HIDs on my car for a decade.

Now I don;t know about the v6 models but the GT's came with an archaic single phase alternator. Nobody uses those anymore. If you get a replacement it will be rebuilt or remanufactured. There are a few new ones still floating around and I got one sitting on my shelf that I snatched up when I saw it. Anyways, GT owners have solved the issue by getting the 2010 alternator and putting it in our earlier models. I am on my 5th alternator but this last one was the 2010 3-phase unit and it has been going strong for a few years now. The first 3 were factory single phase units replaced under warranty. The 4th was rebuilt Autozone unit (single phase).

Clapper

So the shop just called and said they found the problem. The positive battery cable was partially melted due to a bad connection and was failing, causing the alternators to wear out and the headlight flicker. I am still not sure how /why, but they swapped it out and the headlight flicker is GONE! Alternator and battery are fine. So I will get the car back and drive it for a while holding my breath. If the problems don't come right back, I will happily return to confirm this victory over the electrical gremlins. If not, I will come back to confirm that they were wrong and we still have a mystery. Thanks!