[ab0wl0fc3r3al]

Hey brothers/sisters, I just replaced the alternator in my 2005 Mustang GT and since then my battery light has come on and it keeps telling me to check my charging system. I went and had it tested at autozone and they said the charging system, alternator, starter, and battery were all working fine. I also bought a brand new battery before I put in the new alternator and drove it over to my friend's house with the old one in there to put the new alternator in (the old one wasn't working so I was running off just the battery). I safely assumed that the battery got drained on the way over there and I let the new alternator give it some juice which seemed like it worked fine. But when I drove off and pressed in the clutch after switching gears, my battery light came on and it told me to check my charging system. I also noticed that when I press the clutch in after revving my engine, it goes all the way down to 500 rpms, sometimes lower, and then jumps all the way up to 1500 before idling steady at around 750 rpms. It has actually gone down low enough to shut off and it has become troublesome. I checked the belt and everything and everything is connected correctly. Idk what I did wrong or what's wrong with it. This is the alternator I bought: http://www.amazon.com/gp/product/B00CF5KTWW/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
It's 135amp
Has anyone else encountered this problem after changing the alternator? And if so, how do I fix it?
Here is a video of me revving the engine, like I said above, it usually goes all the way down to 500rpms and then goes up to 1500rpms before going steady at around 750rpms. https://www.youtube.com/watch?v=DyLk7QVxEIk&feature=youtu.be
Thanks in advance everyone!

 

[Tbones80]

Bad alternator is my bet. Theyre known for being bad, even when they test good. Brand new ones too. 05-09 mustangs use a 2 phase alternator. Junk. Ford trying to save money. Buy an alternator for a 2010. Its a 3 phase, much better quality and bolts right up.

 

[ab0wl0fc3r3al]

Bad alternator is my bet. Theyre known for being bad, even when they test good. Brand new ones too. 05-09 mustangs use a 2 phase alternator. Junk. Ford trying to save money. Buy an alternator for a 2010. Its a 3 phase, much better quality and bolts right up.

Okay, thank you! Do you have any recommendations on which one to buy?

 

[Tbones80]

Okay, thank you! Do you have any recommendations on which one to buy?

A Ford OEM for a 2010. Its hit and miss with other brands such as PA. Try and buy it from a store with lifetime warranty. Covered both ways then.

 

[ab0wl0fc3r3al]

Hey brothers/sisters, I just replaced the alternator in my 2005 Mustang GT and since then my battery light has come on and it keeps telling me to check my charging system. I went and had it tested at autozone and they said the charging system, alternator, starter, and battery were all working fine. I also bought a brand new battery before I put in the new alternator and drove it over to my friend's house with the old one in there to put the new alternator in (the old one wasn't working so I was running off just the battery). I safely assumed that the battery got drained on the way over there and I let the new alternator give it some juice which seemed like it worked fine. But when I drove off and pressed in the clutch after switching gears, my battery light came on and it told me to check my charging system. I also noticed that when I press the clutch in after revving my engine, it goes all the way down to 500 rpms, sometimes lower, and then jumps all the way up to 1500 before idling steady at around 750 rpms. It has actually gone down low enough to shut off and it has become troublesome. I checked the belt and everything and everything is connected correctly. Idk what I did wrong or what's wrong with it. This is the alternator I bought: http://www.amazon.com/gp/product/B00CF5KTWW/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
It's 135amp
Has anyone else encountered this problem after changing the alternator? And if so, how do I fix it?
Here is a video of me revving the engine, like I said above, it usually goes all the way down to 500rpms and then goes up to 1500rpms before going steady at around 750rpms. https://www.youtube.com/watch?v=DyLk7QVxEIk&feature=youtu.be
Thanks in advance everyone!

I also forgot to mention that my check engine light came on and I have multiple random misfires even after changing the spark plugs so I'm thinking it's the coil packs.

 

[ab0wl0fc3r3al]

A Ford OEM for a 2010. Its hit and miss with other brands such as PA. Try and buy it from a store with lifetime warranty. Covered both ways then.

Alright, I'll try that. Thanks again!

 

[Bullitt95]

I also forgot to mention that my check engine light came on and I have multiple random misfires even after changing the spark plugs so I'm thinking it's the coil packs.

No. It's probably the bad alternator that's causing the misfires 'cause there isn't a high enough voltage reaching the coil packs.
The voltmeter in your gauge cluster is all the way to the left so that confirms you have a bad alternator. The 2010 OEM 3-phase alternator is a definite improvement over the 05-09 single-phase 6G unit.

 

[sqidd]

Check your PM's

 

[ab0wl0fc3r3al]

Okay guys, got the new alternator and when I went to switch it out, I found the culprit that was causing all the trouble. One of the wires on the wiring harness that connects to the alternator came loose and popped out. It looks like the guy before me just tried to shove it back in without replacing the broken harness. You guys know if I have to order a new harness from ford or does a regular auto parts store sell them?

Thanks!