so i went to start my car last weekend and it wouldn't start. found out the battery was bad and got a new one. took it to a auto shop and they tested my electrical. turns out the alternator is bad. no problem, i'm gonna replace it, but i have a couple questions. could bad electrical connections have made the alternator go bad? if so, i am posting pics of how my wires are connected. if someone sees an issue can you tell me what it is? i put in a new wiring harness and followed the wiring diagrams i was able to find. i just don't want to replace the alternator and have it go bad and then have the battery go bad and have to replace them both because of a faulty conection(s). thanks.

Image 1: this is how the wires are connected on the back of the alternator (2 wire). the black/red wire is the ground (terminal says "GRND" next to it) and runs to the block where the negative cable from the battery is connected. the yellow/black wire with the brown cap is connected to a terminal on the alternator that has "BAT" written underneath it. i assume this means battery. not sure what the white wire with white cap's terminal says underneath it, but i assume it connects to the regulator. heres the pic:



Image 2: this image just shows where the black/red wire is grounded to block with the negative cable that goes to the battery. heres the pic:



Image 3: just in case i am also posting this pic of how things are hooked up on the solenoid. heres the pic:

 

well your wires are in excellent condition it looks like

 

Wiring looks correct from what I see in the pictures. The white wire goes to the regulator and is your "field" wire.

When replacing the alternator it is a good idea to at a minimum check the regulator. If you have the old point style regulator, and you are not staying concours correct, I'd suggest replacing it with an electronic version.

As for what makes an alternator go "bad". Lot's of things. Old battery with high resistance (or very low resistance), Poor grounds, voltage drops, old age, excesive heat, disconecting the alternator with the engine running, Intermittent opens in the B+ wire, etc.

Did they explain what "bad" meant, when they tested it? That would help in determining if outside influences had any affect.
open diodes is usually a result of intermittent opens in either the ground or positive circuit, or a load that stressed the alternators output for a good length of time. Stator issues are most commonly associated with high temperature, or again an excessive load that caused the alternator to run hot, or an alternator fan that is installed backwards. Brush issues could be extended use, loose stator rings or worn bearings.

There's just all kinds of things that can happen. I personally dislike the use of the word "bad" when describing a failed component. My first question is always..."OK, so what is bad about it?".

You have a very clean looking engine bay. I'd look to make sure the negative cable lug is attached to clean bare metal on the engine block. Then make sure that the ground strap between the engine block and body is clean and attached to bare metal. Also the same for the grounds at the upper right side of the radiator support, and the ground at the voltage regulator. I always sand these areas to bare metal, and I also sand the eyelet lightly as well. This helps insure there is no voltage drop or intermittent, voltage drop.

BTW: who ever it was that kept breaking their alt belt needs to look at your belt. That is the correct width belt. Hope he sees this post with your excellent pictures.

Good luck,

 

so i pulled the alternator out and was wondering if i have the wires connected correctly. i had the black/yellow wire connected to the terminal marked "BAT" for battery I assume, the white wire connected to the terminal marked "FLD", which from the previous post i think means Field, and the black/red wire to the terminal marked "GRD" which means ground. their is also a terminal marked "STA" which im not sure what it means and had nothing connected to it. also, their is a terminal with no marking that had nothing connected to it. see pic below:



is everything connected up correctly?

i am taking the alternator to get tested and ill post my findings with probably more questions. thanks.

 

Do you have it hooked up like this?
http://www.cjponyparts.com/TechAltWiring.asp

 

yes. that diagram is exactly what i was looking for. thanks. i went and bought a new alternator after having the old one tested. it failed at the ripple voltage test with numbers like this:

2.31 High Limit 2.

Bt Voltage:
Low - 13.7
Actual - 14.59
High - 15.70

i was told it was probably the diodes that went bad from wear and tear.

what these numbers mean i have no idea. maybe someone else does. im gonna put in the new alternator. should i replace the regulator even though i just replaced it about 8 months ago? i read somewhere that if the voltage regulator is connected while the battery is connected or is not affixed to the body of the car it can burn out. i'm gonna check all the grounds. do i need a ground running from the starter? i didn't have one when i replaced it and can't find where to connect one on the current starter.

 

Glen, that is an excellent link!
Great find!

Caballo66, take your regulator with you, and when they test both parts, ask them to explain if there are any deficiencies.

Scott

 

well i think i found the problem. while i was checking all the electrical connections i notice the connector to the voltage regulator wasn't even connected (actually, only the bottom terminal was connected as the whole thing was at an angle, the other 2 weren't even touching). i think it got pulled loose when i pulled on the other end of the wiring harness by the solenoid to pin the harness to the wall of the engine compartment to get it out of the way and clean up the engine compartment. so...could the voltage regulator have gone bad not being completely connected? i forgot to take it with me when i got the alternator tested so ill probably go back and get it tested, or just buy a new one and not take any chances.

another thing i was wondering is on the voltage regulator their is a terminal at the very top of the row of terminals that is marked "I". the connector just has an empty space and does not make a connection to that terminal. is this correct? the other 3 are marked A, S, and F.

also, from the "A" terminal there are 2 wires. one goes to a plug that has a tag that reads something like "only connect for radio supression". to that plug i have this cylindrical part connected via a wire. is this correct?

thanks for all the help.

 

Your starter grounds by being bolted to the engine, so you will not have a separate grounding wire to the starter. I was told many years ago by some pretty smart mechanics that you automatically replace the VR when you replace the Alternator. And, that little round cylindrical thing that hooks onto your VR is the supressor for the radio. The old AM radios crackled and had interference noises unless you had that thing hooked up. But, if you have a modern radio in your car, you won't need that.
On Edit: The VR only plugs in one way, so there is no need to worry about plugging it in wrong.

 

Just to add to Soarings good follow up post. The "I" on your regulator stands for "ignition" This is not used on our year vehicles. So it stays empty.

Great find! I seriously doubt you hurt the regulator by it being partially unplugged. However, if you still have charging issues definitely have it tested. And as Soaring said, it's always a good idea to replace the alternator and regulator as a pair. So if you replaced your alternator this would be a good time to change the regulator, and go electronic (if it all ready isn't).

Good job!