New Alternator Problems

[RonD]

No computer involvement prior to early 2000's for most charging systems.

They are self contained from 2G models and up, 1G had external voltage regulator, 2G has internal regulator.

In your case, when voltage drops with engine running I would test voltage at B+ on back of the alternator, use alternators case as the Ground and then test voltage at the battery terminals.

If B+ shows 12volts then issue is the alternator, it is OFF, for sure
If B+ shows 14volts and battery 12volts then alternators B+ wire is disconnected from truck wiring

Why an alternator turns off can be a few things, all related to the 3 wire connector for the voltage regulator
The Yellow wire is the feedback voltage for the regulator, it tells the regulator the AMP draw of the vehicle, 0 volts here turns off alternator.
White jumper wire connects regulator to stator(field coils), if it is disconnected alternator is OFF.
Green wire is the Battery Light wire, it comes from the dash, it is also the ON/OFF switch for the alternator
When you turn on the key the Battery Light should come on, after you start the engine the Battery Light should go off....IF...............alternators B+ voltage is the same as cab fuse panel voltage, 0 volts here(key on) will turn off alternator

 

[Denisefwd93]

Ron this is all good trying to help, but the OP just takes it to others.

 

[RonD]

Ron this is all good trying to help, but the OP just takes it to others.

Yes, and hopefully he will print it and take it to the "newbies" working on it

From 3rd post in this thread:
"Told guy about what you said and he said his computer would tell him."

??? computer would tell him........................

Everyone has to learn, I don't hold that against newbie mechanics, I still am one after 50+ years, lol.
But you do NEED TO LEARN, and it takes a few years to learn the one thing that will serve you the best............you are not smart and you don't know everything, then the learning begins

 

[PonyUp]

Thanks to all who are patient and generous with sharing. OP<<<Me had major shifting issues and had car towed to tranny shop. Then tranny guy had a resident mechanic put another alternator on. Car was 50 miles from me and since I have a job taking care of elders in their homes, I had to go to work and let someone else take care of car. The car then went 6 miles down the road to the current shop. I am listening and I did email your first suggestion Ron. Thanks. Will email the last one as well. BTW....don't know how it works in your part of the country but around this part of Texas, it is challenging to give 3rd party suggestions to mechanics. Being a female adds to that. My reg mechanic is 65 miles away and does not work on granny's or I would have towed it to h I'm the first place. Oh and PS>>>>The drop happens with engine on, in park and just turning lights on. Nothing at all turned on except engine running, as soon as it is put in drive, it drops. Thanks again for those who have made time to share numerous possible routes.

 

[JerryC]

The drop happens with engine on, in park and just turning lights on. Nothing at all turned on except engine running, as soon as it is put in drive, it drops. Thanks again for those who have made time to share numerous possible routes.

Ok, this makes me wonder... did they fully charge your battery before replacing the alternator? It could also be a parasitic drain on the battery, explains why they thought it was fixed but you shop later and it isn't.

Here's why I think this is a possibility, the engine speed drops in gear and so does the alt output. it might not be spinning fast enough to handle the load of an undercharged battery and drive the vehicle electrical load.

A simple test is to rev the engine and measure the voltage. Turn on the headlights and rev the engine up to about 2500 rpm and see what voltage you have. Or look at the headlights and see if they brighten up. If the wiring or regulator is the cause the voltage won't rise with rpm.

 

[JerryC]

When you say the idle drops, how low in rpm is it going?

 

[RonD]

".........it is challenging to give 3rd party suggestions to mechanics"

Yes, many younger ones, and even some older ones, haven't learned the main lesson in life yet, and it applies to all fields of endeavor, not just mechanics

"You are not smart and you don't know everything", prior to learning that you are just passing thru life, not learning anything new
Like talking to a teenager, lol, they know everything and "we" just don't understand

Doctors are the worst for this, even more than mechanics, lol.
Only thing you can do is find another Doctor, or Mechanic, who is smart enough to know he(or she) is not smart and doesn't know everything
There is nothing wrong with being confident in what you think you know, like a teenager, but you still have to be open to a new or another approach to a problem or idea, unlike a teenager

 

[PonyUp]

Jerry, idle drops to below 1/2 when usually goes no lower than right below the first line on gauge. Yeah Ron, I have banished all mechanics in my small city/town now. Usually just take it to the guy 65 miles away but car was not going to make it and was thinking how hard are alternators to change? Lol. Changed one on my 3/4 ton Chevy truck years ago and as a non mechanic it only took me 1 hour of actual labor. I am kind of wondering about something...after the first alter at or was installed and I knew something was off, I went home and was going to take the alternator off a 89 which was totaled 6 years ago a d I bought back for parts. Already pulled the new tires off, fan, starter and rotors. When I looked at the wrecked 89 alternator and then my current 89, they are different alternators. The connections are different too. Looking at the one just replaced, I saw some wires had been crimped together and they looked brand new. No dust or road dirt. Brother said current 89 could have been a later 89 model hence the difference? I looked up VIn # and it is coming back as a 89 like the title says. But Ins company said it was coming back as 90 when I first put it on policy. Made them cha he it to the titled year. Wonder if first shop put on wrong type of alternator and just spliced in the wires or are the brackets different as well. Weird 2 1989's and different style alternator s.

 

[Ozwynn]

best upgrade I made to my 1990 F150 was a 3g alternator. just sayin

 

[JerryC]

Idle in gear at ~500rpm? yeah, that's not good. I think that alone could drop your voltage considerably. As a wild guess, look at the spark plug wires on that side. Might be the first guy knocked one loose replacing the alternator or worse, he damaged one. Just in case, I'd also check the firing order to be sure the wires are in the correct spots.

If the airbox on your 90 is like my 88, there is a vacuum line to the airbox to control the flapper valve for hot air off the exhaust that runs in that area. See if that got knocked loose or damaged.

 

[PonyUp]

A simple test is to rev the engine and measure the voltage. Turn on the headlights and rev the engine up to about 2500 rpm and see what voltage you have. Or look at the headlights and see if they brighten up. If the wiring or regulator is the cause the voltage won't rise with rpm.

They did not do that while I was there. Putting car in drive with nothing turned on, drops idle and gauge needle to 1/4 mark until I get it up to 2000 RPM. Needle goes back up to just below 1/2 mark at 2000. But driving it at 2000 RPM and turn AC on needle drops to 1/4 mark and AC blows dang cold air. Let off gas to slow down and gauge needle drops to 1/4 on gauge without AC on. Slow down with AC on and it drops down just to the right of red area. Engine in drive and AC on while driving under 2000 RPM, gauge it almost to red area.

Before I took car to get 3rd alternator, I did check vacuum lines and for any loose anything. Except the spark plug wires. But car starts up just fine and engine doesn't really "miss", just a low idle.

Now that you mention it though, I did notice there are 2 lines coming off the left top side of engine block, near the front One goes to box where the air filter is and the other goes into the "wall" of backside engine compartment. I have 2 1989s and a donor 1990. Those hose/lines are not matching up the same. Kind of like the alternator on both 89s are not the same. My manuals are in car at the shop and will get them tomorrow to see if I can find where those lines are supposed to go. Thanks Jerry.

 

[PonyUp]

Charging system is not all that complicated, surprised about this ongoing issue

Battery voltage, engine off, I assume is 12.6v
With engine running, alternator takes over and system voltage will be above 13.5v
If at anytime when engine is running, and the system voltage drops to 12.6v then alternator is OFF or is disconnected from the vehicles electrical system.

This can be B+ terminal on alternator, or wire from B+ to Power distribution post(starter relay).
OR
Voltage regulator has cut voltage to alternators rotor, turning alternator OFF

Unlikely but possible is that the Alternators bracket is not a good Ground, or Battery's Negative cable to Engine is not a good Ground
Some do run a ground strap or cable from alternator bracket to Batteries ground cable on the engine or to other known good ground point
Bad ground for alternator and/or voltage regulator turn alternator OFF

Thanks again Ron. He read your info I sent him. He said the wiring you described is different than the wiring he was seeing on those connectors. This 89 and the donor 89 have different style alternators/connectors. Are the alternators "bracket specific"? Why would same year have different types? When I was looking for loose wires connections, I noticed the three wires coming from the side connector on alternator, had all been crimped inside clear colored plastic connectors. Last alternator guy redid them and wrapped them after he tested them and said wiring was good.

Sooo...current shop is getting another alternator and new wiring. Said they are not charging me. But he said it was showing a 65 amp as being OE for a 1989.

Do you think the current electrical issues has anything to do with my tranny issue?

Don't know that I can ever Thank all of you enough. Thanks.

 

[PonyUp]

Does this actually mean what it says??????

"The engine block is clean. (Brother took it out and replaced seals/gaskets and painted it silver so I would notice any leaks.)". ???

This may be when your electrical problems started, maybe not right away but not long after...

Brother was a working mechanic for years and though he will be the first one to admit he doesn't know everything, he will figure it out and he knows how/what kind of paint to use. He worked on a few "show" cars, as well as owning, rebuilding a few vintage classics of his own.

The current issues, I eased off picking his brain due to some medical issues he is going thru with his wife. That and car was not able to be driven to Kansas or I would have ToTo.

 

[RonD]

1989 Ford Bronco II Eddie Bauer 6 Cyl 2.9L was 80amp??

He should use an 80amp alternator if available, that will output 45-50amps at idle, 750-800rpms
If you have power windows that would be correct amp rating, and I thought all Eddie Bauer models had the "power group", windows and door locks?

65amp would only have about 35amps at idle
This wouldn't cause the voltage drop you are seeing/describing, the sudden drop means alternator is shutting off completely, or disconnected from vehicle's electrical system

2G and up alternators all work the same wiring wise, only change was 2 or 3 wires at voltage regulator, white jumper wire was internal on the 2 wire.

You can give mechanic this link: http://www.fuelinjectedford.com/page63.html
It shows wiring diagrams from 1G to 6G

There are "one wire" alternators, literally only 1 wire from the B+ terminal to Battery Positive via a Mega Fuse
They use an internal RPM switch that closes when rotor spins at a high enough speed, usually at about 600RPM at the engine
That switch replaces the Green ON/OFF wire
The internal voltage regulator monitors voltage(yellow wire) via B+ connection
The stator wire(white jumper) is internal
So just one wire is needed

Why don't car makers use them?
The RPM switches are not that reliable long term, and you lose Battery Light "no charge" indicator, although Voltage Gauge would still work and show a drop in voltage if alternator quit working


A4LD automatic only had 2 electrical components, Torque converter lockup solenoid(TCC) and the Overdrive solenoid(3/4 shift)
These 12v solenoids have an operating range from 5 to 20volts, so wouldn't be an issue running at 9-12 volts
The Engine Computer(PCM) that runs the solenoids is more susceptible to "brown outs", but 12v is normal startup voltage for computer, and when starter motor is active system voltage can drop below 10volts so your voltage drop wouldn't effect computer, or solenoids.
So lower voltage shouldn't effect automatic transmission
BUT............alternators do generate AC Voltage, which is converted to DC Voltage by Diodes, and these can fail in a way that lets AC Voltage run thru to the vehicle's electric system, AC volts can cause very odd problems in DC systems

 

[PonyUp]

Thanks again Ron.

Car is back with tranny guy. So called "electrical shop", put a new alternator on and a new plug going to bottom of alternator. I drove before payment and the chrge gauge is staying pretty much in the middle. Idle is better. But I am leary. The alternator they put on came with a pulley for a serpentine and they could not use that. They used the single pulley off the last put on. I did not realize that until I saw the one I paid them a core fee on in order to return to last guy for a possible refund. I looked in box and there was no pulley or nut at all. I called the and they told me the "situation" and forgot to put serpentine pulley in box. They told me the guy should refund even if it is not the pulley it is supposed to be. Yeah, I will find out today.

My concern is if it came with a serpentine pulley and my car uses the single, could it be the wrong alternator?

I also found out when they put the last alternator on, they has messed with the screw next to the throttle body (?). I had marked that screw and my understanding it is not used to adjust a low idle. Especially since the car had no idle issues before the first alternator was put on. Maybe because they put a new IAC on?

Thanks again to all for your help and education. You also helped me re think hiring someone to beat these money grabbing fools up.