kevdog442

I'm switching the alternator in my 68 Cutlass to a internal type. I bought the conversion kit (adapter plug, and block plug of the regulator) works but I'm getting 16-17 volts. Checked at the battery and with a guage. Took the alternator and had it tested at autozone, and they say it's putting out 14 v and it's fine. Could it be a wiring or ground problem?

kevdog442

Internal regulator type

joe_padavano

If the alternator is putting out 14V, there's no way for the voltage to be higher without a transformer. What's the voltage across the batter terminals with the engine off?

garys 68&72

Lots of possibilities here. Is the alternator a 1 wire or 3 wire?

garys 68&72

Actually it can put out much more than 14V. A failed diode will cause this or if a 3 wire alternator, a voltage drop in the sensor wire.

kevdog442

13.5v with engine off. This is a 3 wire. 14v with engine on. When the rpms go up voltage goes up.

kevdog442

Also ( not that it matters) but the alt. is new.

garys 68&72

Measure voltage at the alt sensor wire. Most likely someone tapped into it causing a voltage drop in the sensor wire to the alternator.
If voltage at distribution point is high and sensor wire reads normal, that's your issue.

kevdog442

Ok not really sure what the sensor wire is but here's what I found.
Engine off 12.8v, engine at idle 15v, 2 wire plug that goes into alt 12.7v, terminals on alt were 2.2mV and ~125mV.

BUT today it stayed at 14.5 v. No change with rpms. Seems normal. May be ok now.
I may never know what the deal was yesterday.

billmerbach

Just throwing this out there could your belt be too tight?

kevdog442

We'll I did have it off to have it checked. Hmmmm

kevdog442

Driving around town yesterday the voltage sometimes got up to 15.5 is that too much? Seems to fluctuate between 14.5-15.5v

billmerbach

That sounds like a belt issue

garys 68&72

OK, check this.
3 wire alternator has the big output wire, a sensor wire (hot all the time) and excitation wire (hot only with key on).
Check the voltage of the output wire when it's high, ie 15 volts. Then check the sensor wire. If the sensor wire is 15 volts too, you have an intermittent diode in the regulator failing.
If it reads normal, ie 13 Volts, you have a wiring issue in the car.
One other note, with the failing diode, the voltage will vary more with engine rpm.

MDchanic

And it's not the belt.

Just because a slipping belt can give you low output does NOT mean that a tight belt can give you high output.

- Eric

billmerbach

The old man lied to me and hell denied it but he told me that

MDchanic

"Believe none of what you hear, and half of what you see."

billmerbach

But I trusted my dad

garys 68&72

I thought he was joking.....still kinda do....

billmerbach

Not joking dad told me not to tighten the belt cause it'll overcharge the battery

billmerbach

Over tighten

MDchanic

If you overtighten the belt, it can damage the belt or the bearings.

- Eric

billmerbach

Maybe that's what he meant he just said otherwise lol he's getting old

garys 68&72

Well...dad was wrong...
And he really didn't walk uphill to school both ways....
Never drove the car into a bridge abutment because you were misbehaving in the back seat...
You couldn't "walk off" every injury...
And you really were not holding the flashlight wrong when he was fixing something...
Wow, I hope you're not completely disillusioned now.

billmerbach

I don't how to respond...

garys 68&72

Your mom was right about things that could poke your eye out....
But she really never knew anyone that lost their arm hanging it out the car window.

kevdog442

Ok so I have a big wire, it reads 15+v. The plug has 2 wires, both have very small voltage. There doesn't seem to be two wires that have at least 12v with engine running.
Can't find any evidence of anything tapped into the wires they all look stock ( just old)
I went and bought another alternator to try and it was above 15v too. So I returned it.
My old alternator with an external reg. never put out more than 13.5v.
So I'm thinking the wires are fine. But I don't know,

oldcutlass

When an alternator is putting out a charging voltage it's usually around 14.2-14.5ish volts. Are you sure the meter your using is accurate?

stellar

Take volt readings with key off at battery, at alt post, at alt plug (plug disconnected from alt) on each plug connection. This is 4 volt readings. Make a note of each Test again with key on to run position, engine not running.. Post volt readings. I suspect you may have the 2 alt plug in wires reversed, or sense wire is bad.

garys 68&72

What is "very small voltage"?
One wire should have full 12 V when the key is on. It's the excitation wire, it tells the alternator to charge.
The other wire is the sensing wire. It taps off the distribution point (fuse panel/horn relay). It tells the alternator if the voltage is low at the distribution point. If that is reading low, the alternator will try to put out enough voltage to bring it up to about 13 V. That's your issue, your wiring is messed up.

kevdog442

My meter and the voltage guage in the car read the same. So I'm pretty sure it's accurate.

kevdog442

I'll do some more checking but here's what I found earlier.

Engine off 12.8v, engine at idle 15v, 2 wire plug that goes into alt 12.7v, terminals on alt were 2.2mV and ~125mV.

garys 68&72

I hate to ask this, but did you remove the old regulator and hook the excitation/sensor that were connected to the old regulator directly to the new alternator?

starfire

How about their head?

http://www.wsbt.com/news/local/coron...crash/26499388

garys 68&72

Vomiting out the window of a minivan at 2:00AM.....not the way I want to be remembered or check out.
If I have a choice it will be "blasting across the alkali flats in a jet-powered, monkey-navigated".....nevermind.

kevdog442

No I bought one of those conversion kits that has a block that you plug in to the regulator, and a two ended plug that changes the plug type.
Should have been a straight, easy swap that's what has be baffled. I had no problems with my old external reg. setup.

MDchanic

Wait a minute. Over the past ten days, I lost track of the fact that this was a conversion.

Just connect the alternator the way it's supposed to be connected, without the adapter wiring.

• Big red wire to the big post on the horn relay.
• #2 terminal (most clockwise when looking from the back) also to the big post on the horn relay
  (Use ¼" spade female terminals to connect to the two flat alternator terminals).
• #1 terminal to the brown wire that used to go to the #4 terminal on the regulator
  (Use a ¼" spade male to plug into the flat regulator harness).

Tell us how that works.

- Eric

kevdog442

Would it make any difference that the kit was for a Chevelle? I ask this because I was looking at how it said to do it in the FAQ (442.com), the terminals that were jumped together on the regulator appear to be different than what was in the kit.

MDchanic

No, they should be exactly the same.

However, if the instructions were different, that's a different question.

What did the instructions say?
Can you post them?
Can you post a photo of the parts in question, like of the adapter wire laid out flat on a white surface?

- Eric

kevdog442

FAQ site: