Alternator overcharging

[Yarb]

Order one with the pulley.

[SteveJ]

36 minutes ago, chaseincats said:

From the pic on the rockauto part page it looks like I'd need to yank the fan off of my current alternator and transfer it to the new one somehow, no?

The SKP alternator for the 4 cylinder Frontier has the correct pulley. All of those that I have installed worked just fine.

[chaseincats]

Thanks all, good to know.  Before I jump ship on this alternator though, I do want to find the possible issue with my wiring harness

[Zed Head]

4 hours ago, SteveJ said:

Just to be clear, you have to alter the wiring so that you have this

 

4 hours ago, chaseincats said:

Since this car is a '78 it is the only 1st gen year that doesn't have an external regulator and uses what became the ZX alternator

Seems like the basic questions is - do you have the proper voltage at the S pin, and is the S supply consistent during operation?  The problem is overcharging.  You can run a completely separate jumper wire from the battery positive to the S pin and see what happens.  If things start working correctly then you can get in to the harness.  If they don't then the alternator has a problem.

[chaseincats]

2 minutes ago, Zed Head said:

 

Seems like the basic questions is - do you have the proper voltage at the S pin, and is the S supply consistent during operation?  The problem is overcharging.  You can run a completely separate jumper wire from the battery positive to the S pin and see what happens.  If things start working correctly then you can get in to the harness.  If they don't then the alternator has a problem.

Gotcha, it's just odd that it fixes itself everytime I change the alternator out.  But I'll give that a look today.

[Zed Head]

There was a statement earlier about affecting something when you changed the alternator.  So, next time, if you try again, you can do some testing before swapping.  It might even be enough to just wiggle some wires.

[Captain Obvious]

21 hours ago, chaseincats said:

E: Black wire
B: White with red stripe wires (condenser's WR has been connected to the terminal via a ring terminal instead of the original bullet connector)
S: White with red stripe
L: Blue with white stripe that becomes blue with black stripe after the electrical tape I think (the wires are dirty so it's hard to see) 

Good. Those colors match the 78 wiring diagram I'm working from. That page EE-15 from the 78 manual is all kinds of messed up.

Bottom line is you should have the same voltage on both the W/R wires at all times. So if you're taking voltage readings, it would be good to get one with the car off, and another one when the problem is occurring. One lead to the alternator body, and other lead to the W/R wires.

And the idea that Zedhead suggested would be a good test... When the problem is occurring, if you jumper between the two W/R wires, does the problem go away? You don't have to run a fresh wire all the way from the battery to run the test, just run a wire between the two W/R right on the back of the alternator and see what happens.

[Captain Obvious]

21 hours ago, chaseincats said:

Oh, and it looks like your PO was into the harness. Always suspect when that happens.

The W/R that goes into the twp position connector... What direction does that wire head? Does it turn the curve and head into the harness? Can't tell on the pic because the tape flap is in the way.

[chaseincats]

1 hour ago, Captain Obvious said:

Good. Those colors match the 78 wiring diagram I'm working from. That page EE-15 from the 78 manual is all kinds of messed up.

Bottom line is you should have the same voltage on both the W/R wires at all times. So if you're taking voltage readings, it would be good to get one with the car off, and another one when the problem is occurring. One lead to the alternator body, and other lead to the W/R wires.

And the idea that Zedhead suggested would be a good test... When the problem is occurring, if you jumper between the two W/R wires, does the problem go away? You don't have to run a fresh wire all the way from the battery to run the test, just run a wire between the two W/R right on the back of the alternator and see what happens.

The W/R wire that goes to the alternator’s T-connector isn’t included in this check, right?

Good catch on the tape flap, I grabbed another shot after giving it a haircut.  It does go back into the harness:

 

[Yarb]

Are you familiar with using a volt/ohm meter. I may have missed it but In don’t see any measurements being made.

[Captain Obvious]

Thanks for the post haircut pic. Much better.

So as for the test... Yes, the "T" connector is involved.

When the problem is occurring and the alternator voltage is too high, try sticking a wire in the back of the "T" connector at the W/R wire and connect the other end of that wire to the other W/R at the BATT connection. Here's a pic of the back of my alternator. Jumepr the two W/R red wires together like this:

[chaseincats]

55 minutes ago, Yarb said:

Are you familiar with using a volt/ohm meter. I may have missed it but In don’t see any measurements being made.

All my measurements are on post #23