1965 Ford Mustang alternator & harness-diagnostics & replacement.

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We want your thoughts and comments below. What kind of project are you working on? What Mustang are you daily driving?
Today at Alf's Mustang Garage we have a 1965 Ford Mustang with a charging stystem problem. In this video we show you a few tricks on how to diagnose the charging system and we show you how to remove the alternator, harness and reassemble.
Alf's Mustang Garage is not responsible for any mechanical or technical error that you may encounter when working on your own car. You are responsible for your own quality control and your own proper repairs.

[@AlfsMustangGarage]

We are here to keep your classic Mustang on the road and out of your garage. Subscribe to the channel and click on the notification bell. kzbin.info/door/Zi2JnDfxDHwqJoxJzFnIlA

[@jodihouts9560]

Do you work on mustangs. I am in Omaha be. Where you at?

[@jodihouts9560]

Ours is called honey gold

[@CodHumors]

The best video for diagnosing a charging issue I have found. Super important information here, thank you for sharing

[@AlfsMustangGarage]

Thank you! Glad to hear you found it helpful!

[@donchapman3809]

Thanks Alf. Just what I needed to see

[@AlfsMustangGarage]

You're very welcome

[@yakmalxc]

Thank you! Followed you step by step!

[@AlfsMustangGarage]

You're very welcome

[@chriscushing6329]

Thank you thank you so much for sharing the alternator wiring. I want to do it right so I don’t mess it up.

[@AlfsMustangGarage]

You're very welcome

[@rafaelguerrero1398]

Great explanation on the wiring on how to troubleshoot.

[@AlfsMustangGarage]

Thank you!

[@RandyB509]

Gawd I've been dealing with this issue for days now I have a 82 ford f250 with the 351 cleveland I replaced the alternator and it's still not charging up watching your vid gave me sooooooo much help ty ty my question where did you get the new harness on the alternator side? And part# ???? Ty so much for your knowledge

[@AlfsMustangGarage]

Oh thanks! Glad it helped. I buy the Mustang stuff from National Parts Depot. I think they sell for the pickups as well.

[@BrandonMinjaresCodes]

Great video! Will give it a go this weekend.

[@AlfsMustangGarage]

Thank you! Good luck and happy new year!

[@leonardgus]

Thanks you saved me again 😁

[@AlfsMustangGarage]

No problem 👍

[@robertclymer6948]

Hey Brother Alf! Nice video. I took my alt off and had it tested. Very low output. I decided to replace it to a new one wire 110 amp upgrade. Old Alt was 75 amp I think it was the original off my 67 mustang big block. Love the one wire install. I took the old Alt apart and found the brushes were bad. Don't know where to find old Ford Alt brushes but will save it for a back up or sell it at the car show. Now I know what the 1 female two male plug/pigtail at the solenoid was used for, lol IMO, the 1 wire is the way to go and upgrading to higher amps for fog lights, and two 10" pusher fans. Thanks for sharing, Cheers and blessings from Motown/Dearborn.

[@AlfsMustangGarage]

Oh ya for sure, very nice upgrade. Those originals are nice to keep around for someone who make be trying to keep things concourse correct. Good job and thanks again for being here!

[@robertclymer6948]

@@AlfsMustangGarage I just love running into your older videos. Always great info! Hope you have settled into your new shop and enjoy it.

[@AlfsMustangGarage]

Thanks! We are fairly settled. I already wish I had a bigger shop 🤣

[@robertclymer6948]

@@AlfsMustangGarage Ahhhhh, the price of success!

[@AlfsMustangGarage]

Lol yup, now it becomes a balancing act to try to work through everyone and still have time for KZbin 👍

[@grivolas2144]

Do not disconnect your battery to test your alternator on modern cars. This only can only be safely done on classic cars.

[@AlfsMustangGarage]

This is true 👍

[@MrVincenzogallizzi]

Yes lots of play but I never adjusted it. Have you got a video that shows the process?

[@AlfsMustangGarage]

I'm afraid I don't have a specific video on that process yet. kzbin.info/www/bejne/aHKxe4RsraerbaM The Doc has a pretty good video on steering play and how to approach finding out where the play is.

[@jackbeanstock7710]

good video ,good info

[@AlfsMustangGarage]

Thank you!

[@cccopado]

Hi Alf, I have a 65 Coupe. I lose all electric when trying to start. The battery is good and the regulator is fairly new. Can you give some advice on what to try? Thanks.

[@AlfsMustangGarage]

I would check connections at the battery and the battery ground. I would also be checking the main electrical plug that goes through the firewall on the engine bay.

[@Mustang-Mike]

Do you have a video on pro’s and con’s and installation for a (Ford Gen 3 ) one wire alternator.

[@AlfsMustangGarage]

I'm afraid I don't

[@jamesrankin9833]

Good stuff!

[@AlfsMustangGarage]

Thank you!

[@Sunbear415]

Great video, thank you. So the problem was the harness?

[@AlfsMustangGarage]

Thank you! On this particular car it was. The car had just been completed on a complete rotisserie restoration. Looks like the wrong alternator harness was installed. Easy to have small mistakes like that when the entire car is being rebuilt.

[@Sunbear415]

@@AlfsMustangGarage I see, thank you very much

[@AlfsMustangGarage]

You're welcome!

[@westkyvideo]

So was this problem the actual alternator harness? I am having a similar problem. Engine starts with Solenoid but not with key.

[@AlfsMustangGarage]

So the problem with this was it had the wrong alternator harness. If you're having problems with it starting, you need to be looking into your starting system and not the charging system. For example, just based off what you told me, you probably have a problem with your starter solenoid. You need to test if it's getting power on key start and that it's transferring the battery power from battery side to starter side.

[@ernestlamoree1503]

Thank you

[@AlfsMustangGarage]

You're very welcome.

[@ronjackson6023]

Good info. Thanks

[@AlfsMustangGarage]

You're welcome

[@MrVincenzogallizzi]

The v. Regulator was unplugged for some reason. All good now Can you advise about the best steering box for 1965 coupè pls? Atm the steering is vague and despite a new power steering is fitted

[@AlfsMustangGarage]

Well that was an easy one lol. So do you have manual steering and looking to upgrade to ps?

[@MrVincenzogallizzi]

I have installed Ps already but still not a good result. Not sure if the steering box is working properly

[@AlfsMustangGarage]

What kind of ps did you install? All factory stuff or an aftermarket?

[@MrVincenzogallizzi]

@@AlfsMustangGarage Not sure , I bought a kit from NPD Depot

[@AlfsMustangGarage]

You probably got the Borgenson kit?

[@jameslangford4748]

I have a 66, 289 and no harness, just loose wires between the regulator and the alternator. I can't figure out where the wires should go. ISF and I forget the last one on the regulator. I Think S goes to the alt stater, F goes to the alt field, G goes to the alt ground, I goes ... where ? Somewhere a small light goes to indicate the exciter wire is working I think. Not sure about ANY of the ISF positions actually. Please advise. Frustrated.

[@marcmaloney3152]

I’m getting up to 16v on my system, and I just replaced the voltage regulator, would it likely be the wiring to the regular? Alternator looks good

[@AlfsMustangGarage]

Well essentially on these setups, the alternator is usually doing what it's told to do. So I would be checking wiring to the regulator or the regulator itself is bad.

[@MrVincenzogallizzi]

Hi, can you advise how test the alternator? I have the same problem basically. thanks

[@AlfsMustangGarage]

Have you tried jumping the "A" and "F" terminals on the voltage regulator while observing the battery voltage with a volt meter?

[@MrVincenzogallizzi]

Not yet, will try tomorrow

[@AlfsMustangGarage]

👍 most cases when I jump the regulator and the voltage spikes, that means the alternator is working properly but isn't being regulated properly. So at that point, a new regulator is likely what it needs. Now on the flip side, if the battery voltage doesn't change, the alternator or wiring would be suspicious.

[@MrVincenzogallizzi]

I’ll keep posted many thanks

[@AlfsMustangGarage]

👍

[@russellcollocott3867]

Hi Alf I have a 65 Mustang Coupe and lost all electric after trying to start the starter engaged for a slit second and then I lost all power. Battery is good and alternator is new, would this be a bad ground problem?

[@AlfsMustangGarage]

That is possible. Always check your basic things first 👍

[@BigKuda1776]

If I upgrade to a one wire alternator do I still need the voltage regulator?

[@AlfsMustangGarage]

No. A one wire alternator will have a built in regulator.

[@BigKuda1776]

@@AlfsMustangGarage but with it built in then I can ditch the voltage regulator box? Sorry I’m a newbie

[@AlfsMustangGarage]

No worries. I don't know if I would ditch it. I would probably leave it there and tape up the old wires in case you or someone wants to put it back to original.

[@eddievantailn2882]

Hello Alf - I have a battery charging issue. My question is regarding the starting relay. Once the car is running I believe that the post that goes to the starter should read 0 volts. This post connected to the starter should read 12 volts only when the car is being started (on crank) is this correct? Right now I see 12volts on the post to the starter even when the car is in the off position. I believe this is incorrect as well. Please confirm

[@AlfsMustangGarage]

You would be correct. You should only see 12 volts going to the starter only when the key is turned in the "start" position.

[@eddievantailn2882]

@@AlfsMustangGarage Could this be a voltage regulator issue?

[@AlfsMustangGarage]

@eddievantailn2882 no. I would remove all wires from the starter solenoid and perform a continuity test across the battery and starter post. If there is continuity there, the solenoid is bad. Could have burnt up your starter too. Usually if there is power going to the starter, the engine cranks over.

[@eddievantailn2882]

@@AlfsMustangGarage I agree and understand totally. If the alternator is bad does it still make that sound like it's attempting to start? If the starter relay and the alternator are good the car should start, right? I should of mentioned this is a new motor.

[@AlfsMustangGarage]

@eddievantailn2882 I'm not sure what noise the alternator is making when you attempt to start but I'll tell you this, when it comes to the starting sequence, the alternator has nothing to do with it.

[@hughphillips67Mustang]

Is there a way to flip the top and bottom alternator brackets so the tension adjustment bracket is on top?

[@AlfsMustangGarage]

Yup, maybe fabricate your own?

[@MCFABRICATION]

Hey Alf I’m having and issue with charging, wiring seems to be correct, when I went to jump the A and F on the plug for the voltage regulator it sparked with the ignition off, then the wire warmed up and I unplugged it quick, Any guess as to why it would be doing that?

[@limburgercheese1234]

I do this test with car running and jumper wire on a pair of vise grips. Just leave on long enough to get a voltage reading. The jumper wire does get hot.

[@rosemcbirney5123]

Which is the wire that turns the dash light out

[@jackinthebox6143]

Is this the one with charging light? I got an amp gauge in mine the black/yellow thick wire runs past it in a loop but seems wired differently to this one. Cant seem to get mine right. Charging backwards!

[@AlfsMustangGarage]

Yes this is for a car with a light and yes they are wired different for one with a gauge.

[@jackinthebox6143]

@@AlfsMustangGarage Thanks, it's also worth mentioning for those who have a car with voltmeter gauge that there's nothing to put on 'Stator' terminal. And the black/yellow battery wire goes right around the car through the dash and back out the firewall to the hot relay terminal. And if your gauge is going the wrong way like mine it could be threaded through the meter loop the wrong way. it's dummy easy to get wrong if you're under the dash everything is back to front. Thanks for this video Alf it's sorted out something which is hard to find on the internet there are so many ideas and conflicting opinions how to do this. Well worth replacing these old wires I just bent the red/black wire a little and it snapped in my hand with no pressure! The old wires are so stiff and brittle.

[@AlfsMustangGarage]

You're welcome. You're right there is lots of information out there and it's different on a gauge vs a light and what not. Glad I was able to help a little.

[@kishandonmathias4620]

I have the mustang 1964 same problem.In regulator what is A and F terminals stand for ? Whats the colour of those wires ?

[@AlfsMustangGarage]

So if you have an early 65 (64.5), you probably have a generator? If so your regulator will be different than an alternator car. On an alternator car, I is for ignition green wire. A is for alternator battery terminal, yellow wire. S is for Stator, white with black stripe. F is for Field, white wire. Foe the generator cars, A is yellow and black (not 100% on what it stands for on generators). F is field white wire and B is red wire goes to the battery side of the starter relay solenoid.

[@kishandonmathias4620]

@@AlfsMustangGarage thank you so much for your reply .Your videos are informative. Please keep uploading.

[@AlfsMustangGarage]

You're welcome! Thanks for subscribing!

[@trentdawg2832]

I have a ‘67 c code car that im getting ready to add EFI too…upon inspection i noticed when the car is running and i have a meter at the battery it is charging and getting its 14v but i noticed that it fluctuates and jumps all around from 5v 8v 12v 14v……but it seems to run fine….i just replaced the voltage regulator and noticed when i unplug the regulator it makes no diffrence

[@AlfsMustangGarage]

Have you tried checking your system with multiple meters? Seems weird.

[@cemalgurel7704]

There was a charging problem, low charge around 12,1 Volts. After the re-build up, it raised to 14.45 Volts. So which part is replaced? The cable?

[@AlfsMustangGarage]

I'm not sure what you're asking.

[@RichW240]

Wrong alternator harness was installed.

[@g.austins5508]

Where does the negative wire from the alternator hook up to the block?

[@AlfsMustangGarage]

Typically goes to the same ground as the battery ground.

[@g.austins5508]

@@AlfsMustangGarage I gotta check out my set up I hace a three wire new alternator and it isn’t charging . I can’t find a place on my block to hook it up or screw on .

[@jodihouts9560]

Where can you get a new harness like that. I have a 65 mustang. Before we put new battery and alternator on and voltage regulator. My dash battery/alt light worked after install lights would not come on.2weeks later battery was dead and read bad. Got a new battery but do not want to put in until I know what’s going on.

[@AlfsMustangGarage]

We got that one from National Parts Depot. There are a few options so just make sure you get the right one for your car 👍

[@jodihouts9560]

I need a good Ford Mustang mechanic in Omaha Nebraska area. I am stumped

[@jodihouts9560]

@@AlfsMustangGarage thanks. I have a 65 mustang 289 v8 auto. No power steering or ac. I believe it only has red lights for battery/ altenator. I found the sight, but trying to find right one.? Our car is automatic. If you mix up 2 white wire will that mess anything up.

[@jodihouts9560]

You have been a big help last few minutes while I am on break and hope I can get it back up running in a week.

[@AlfsMustangGarage]

Whenever I'm trying to figure out the right one of anything, I usually just call and talk to them. But for those alternator harnesses its usually just which engine and if you have an alternator light or a gauge. And you said you have the light. That's usually the difference is there will be a 289 for a gauge and a 289 for a light.

[@christiang3576]

I cannot for the life of me find what the wire is called that connects to the alternator wiring harness, it’s the first two wires you disconnected after disconnecting the battery, would appreciate if you can tell me the name of the wire the alternator wire harness goes into

[@AlfsMustangGarage]

Are you asking about the harness on the car that plugs into the alternator?

[@christiang3576]

@@AlfsMustangGarage yes sir

[@christiang3576]

@@AlfsMustangGarage yes sir

[@AlfsMustangGarage]

Is that the engine gauge feed wire harness?

[@christiang3576]

@@AlfsMustangGarage hmm not sure I’m just trying to figure out what the female plug is called for the alternator wiring harness

[@eddievantailn2882]

You did not show us how the Mustang was incorrectly wired, that would have been helpful.

[@AlfsMustangGarage]

At 6:50 I explain that the harness on the car was the incorrect harness. At 3:10 I explain there isn't a charge back wire from the alternator to the battery.

[@bigdaddy934]

Nice video, but lose the gloves girly man.

[@AlfsMustangGarage]

When you work on a $100K restoration and you get in and out of the car, you wear gloves to protect and respect your client's investment.

[@bigdaddy934]

@@AlfsMustangGarage OK, I stand corrected.

[@AlfsMustangGarage]

But to be honest, I wear gloves on everything I work on. I find it very easy to have clean hands when I get in the car or get into anything I don't want dirty. Gloves come off and bam, clean hands 👍

[@blbenson8548]

I like the girly gloves! 🤓

[@AlfsMustangGarage]

These girly gloves might just be my signature. Now I'm going to have to reference them in every video.