My reman Alternator went ouplaced with another reman. 14.5 volts read. Great
Drove 600 miles, alt. went out.
Replaced with Auto Zone reman. Reads 11.5 V
Have I actually been through 3 alts. in 3 days, or did I get a bad one from auto zone?
Am not happy at all, it is 37 degrees outside under my shade tree.
Any ideas are appreciated.

I have not read this whole thread, but I had a similar issue with a different car. After 3 alternators that my son had a shop install. I noticed the negative battery cable could not be properly tightened. I fixed that with a hack saw but making the gap bigger, and has been fine since. For what it is worth the shop had the car at the time and was adamant the alternator and battery had to be replaced. I jumped it the parking lot and took it home and fixed it. No more alternator problems.
Short version, check your grounds.
--
1991 240 Sedan auto

It is often impossible to distinguish between malice and stupidity.

i would think there are multiple grounds&theyre rusted up
should be cleaned well
'

Makes sense to me. I need to re do every ground.

This is the theory of "lifetime warranty." If they had to pay for your trouble along with the exchange, this method of quality control would never stand.
--
Art Benstein near Baltimore

How come nothing rhymes with orange?
What? Nothing doesn’t rhyme with orange?

Because of having 3 bad alternators on a car in 3 days, and not replacing an alternator on a 240 in 15 years, I have a fear that I have done something wrong.
That is in opposition to the fact that I have replaced 3 bad, though relatively new in tank pumps on 240s.
Changing an alternator though, seems to be one of the simplest jobs on the car; Ground wire, wire to batt. and wire from charge indicator. Friendly young guy at AZone was proud of the fact that his rebuilt alt. uses only the body of the old alt., replacing all the internals before reselling as rebuilt.
Faith, even when in error, is probably a good thing.
Is the usual suspect on a bad alt. the voltage reg./ brush assembly?
I am out of town, but have new brushes, as well as a new bosch voltage regulator at home. (850 miles away.)

Troubleshooting by "usual suspects" is a valid approach, especially when the trouble is intermittent. I'd say the brushes would fall into that high probability range if you were talking about an alternator that has been in your car a while, but one out of a box from Azone would be different. Chances are that simple to rebuild part has been done.

Be sure your harmonic balancer is still in one tightly-held assembly. It may look like the alternator is turning, but if the belts are not tight, oily, or the balancer is slipping, the revolutions will be limited just as the alt's output begins to get serious.

If your battery light works with key on engine stalled, the small D+ wire is very likely OK. Since you replace the unit yourself, you likely know the ground wire is OK. Pretty hard to mess up the B+ wire, like you say, replacing an alternator in a 240 is not specially hard to get right.

Getting home 850 miles without an alternator? Now that's a real challenge day or night.
--
Art Benstein near Baltimore

Why do dogs love humans?
They don’t, they just like biscuits.

Wellll.....
Got out there to remove the alt. this morning, and thought I would start the car and check it out again. Low and behold, when I turn the key to the #2 position, there are no cluster warning lights on except the overdrive lockout light! All inside fuses are good. I am now looking at the wiring diagram to try to see what is amiss.

On a '93 that's a unique circuit. With the previous years that wire ran through an 8-place firewall connector where you could check its continuity to the alt.

What you need to do first is separate the alt from the D+ wire in the suspect list. Do that by grounding the D+ wire (not to the alt case!!) and then testing to see if the warning lights work again with key on.
--
Art Benstein near Baltimore

"If you associate enough with older people who enjoy their lives, you will gain the possibility for a full life." -Margaret Mead

Ground the D+ wire while it IS or is not connected to the alternator?

not connected...
--
'91 244 205k auto

It doesn't really matter, but probably more convenient to ground it with it disconnected. However, disconnecting it may "fix" an issue where the tab connector is oxidized. You are doing this without starting the engine.
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Art Benstein near Baltimore

Why are cemeteries surrounded by gates?
Because there are so many people dying to get in.

Tested by grounding with D+ connected, then with D+ wire disconnected, still no warning lights at #2 key position.

OK, so the trouble is in your wiring, not the alternator. As Derek hints at, the small wire can be broken right under the crank inside the harness. However, there are plenty of other spots for this connection to be missing all the way up to the ignition switch itself.

The next most accessible part of this circuit is at the back of the instrument cluster where that red wire connects to pin 11 of the big round plug.

Here's a diagram showing the D+ wiring from battery to alt through the ign switch, but being away from home, maybe you want to make the trip connecting a temporary jumper between D+ and B+. Doing something like repairing the harness under the front of the engine isn't easy on the road. The only problem with using a jumper is you'll need to disconnect it if you park the car overnight, or the small current used by the alternator will discharge the battery. Worth trying to test, though, to see if you get charging again.


--
Art Benstein near Baltimore

Did you hear about the kidnapping at school?
It’s fine, he woke up.

Well, I am back in Old Kentuck, beautiful weather, and my ailing classic wagon. I removed the wiring from the alt, and checked it back to the driver side of the engine, and all looked good. I then removed the cluster and tapped into the red wire-pin 11. There is continuity from the cluster to the alt connection. Am I now to assume it is the ignition switch? I have a switch, but my old arthritic fingers do not look forward to swapping out that little bugger.

Easy test. Pull the small red (D+) wire from the alternator and fashion a jumper clip to ground the end of that wire on something reliable (not the case of the alt). Get back in the car and turn the ignition switch to KP-II. If you see the usual warning lights on, but only sometimes when you wiggle the key, then you can bet the 28-year old switch has given up its life. If the lights come on solid, the alt has what it needs from this wire. If they don't come on, the trouble could be in the cluster or, very rarely, the key switch failed completely, in which case you probably can't make the motor run after a jump.
--
Art Benstein near Baltimore

What makes a good leader?
Someone who does what they’re told.

Well heck. I performed your test. All lights burned solid, and no jiggling of the switch would affect lights. I re-attached the wire to the alt, and started the engine. 14V output of alt.!! During this job, I peeled back the protective original protective cover past the driver side of engine, installed a new protective loom, and lengthened the batt wire for ease of installation. The car works fine now, but I am uneasy because I found no issue to point to that caused the malfunction.
I fear it is an intermittent problem that will visit me again.
But thanks for the tips. I have a better understanding of the system function now.

This is why I love Brickboard :-)

(Art's wiring diagram.)

(What I don't exactly love is the previous century BBS technology. Oh well.)

Thank you for the nice wiring diagram. I will file it, and use it.
Sounds like you have diagnosed the problem. Its pretty cold outside, and me being a 68 year old Texan and a "cold wimp", I am going to cry uncle.
I am fortunate to be able to leave it parked at my house in Louisville, and will have to return home in the ugly but reliable 90 model 240.
I may, when the weather warms up, take the wiring apart under the front of the engine and see if I can locate the short, or open connection. Might just replace that old stiff high current wire also.

I did some measuring; Key off; Between D+ and grd. 0Volts 15 ohms
Key at #2; " " 1Volt
May get brave this afternoon and try to jump from cluster to alt.
Thank you for the diagram and the suggestions.

Ignition switch is worn.

During troubleshooting I will not be surprised if I end up there.
After 28 years of use, it should be replaced on principle.
Thank you.

Is this one of the cars where the harness runs under the front pulley? Can cause a break in the wiring?

Yes it is.
I will check.
Thank you

37 degrees? That sounds balmy compared to the 11 degrees outside my door. No matter what the weather, 3 alternators is a bummer--and possible. I've learned to only trust a Bosch brand "remanufactured" alternator. That is-remanufactured rather than what is called rebuilt. In your situation I think I'd try the new brushes first. Sorry for your troubles. - Dave