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Not sure but here's one thing I'd like to point out, nobody that has gone the used alternator route has reported any issues (actually I think maybe one person). Many (most) that used a new one, truck or f body, have had problems. So all I can tell everyone is don't start looking at the car and everything on it until you have a known good alternator and the most dependable replacements so far are used truck alternators.
Sucks to hear that. Hope that kg3 comes in soon and takes care of all the trouble. I still remember how aggravating it all was.
The kg3 showed up. It's pretty sweaty looking. lol. Going to rattle can it first. I'm also going to take excitation duties away from the pcm. I'm going to go the other route and pull a dedicated 12v ignition source and run it through a 470 ohm 1/2 watt resistor and install a new weather pac connector. I'll update when I have results.
The kg3 showed up. It's pretty sweaty looking. lol. Going to rattle can it first. I'm also going to take excitation duties away from the pcm. I'm going to go the other route and pull a dedicated 12v ignition source and run it through a 470 ohm 1/2 watt resistor and install a new weather pac connector. I'll update when I have results.
I cleaned mine with a wire brush attachment and painted the pulley and gave it a white wall.
I cleaned mine with a wire brush attachment and painted the pulley and gave it a white wall.
HaH! Lighting McQueen would approve.
I'm beginning to wonder if these alternators fry due to the pcm not "properly" calling for charge. If the signal they send out is weak, perhaps the alternator keeps pumping charge and burns up? That could explain why truck alts survive and f body doesnt. I could be way off here, just a thought.
I'm beginning to wonder if these alternators fry due to the pcm not "properly" calling for charge. If the signal they send out is weak, perhaps the alternator keeps pumping charge and burns up? That could explain why truck alts survive and f body doesnt. I could be way off here, just a thought.
LOL Lightning McQueen sure would.
I understand your thought about the exciter and why you say that, but following the logical path in that... if the alternator was cranking out a high amount they would at some point have an over charge/over voltage situation. Which I have yet to see, it's always under. With that and the fact that just an alternator swap corrected the problem for myself and so many others, shows that it's just the alternator itself.
And also, if there is a bad/no connection situation with the exciter connector, it will set a code and a check engine light. Happened on my car.
I went through every scenario with mine. I'm a full time mechanic and have a lot of diagnostic equipment. I checked my car every time and except the time I had the goofy connection at the exciter wire, the only problem found was the alternator. The connector was an issue on the first alternator if I remember correctly, and I put a brand new one on it. Every single one after that failed with everything else being perfect.
And keep in mind, I had roughly 8 alternators fail in a row with no changes made, not a single one, but the alternator. The last alternator that car had was a used alternator and it outlasted the car, literally. Being that I changed nothing but the alternator, and checked everything else multiple times, proves it was just the alternator itself.
Like you and several others in this thread I started thinking something was causing the failure, and I checked and diagnosed, and ohmed wiring, and checked loads and draws etc etc etc. Nothing ever showed to be an issue, just the alternator.
I was thinking more along the lines of a momentary exciter wire voltage spike. I've read a few threads where guys not running a pcm, have delivered straight ignition 12v to the exciter resulting in an instantaneous failure.
Is there an internal resistor or something along those lines within the pcm that delivers a lesser voltage to the exciter circuit? If so could it intermittently fail?
I wonder if guys running resistors on an ignition 12v exciter circuit have the same failure/success rate as guys running pcm excited alternators?
These are things that had me wondering if the truck alternator was surviving just because it was able to take the punch of a momentary exciter wire malfunction.
I'm not doubting your findings at all, I'm just trying to wrap my mind around the situation more completely than it is now.
installed the kg3. Pulled a dedicated ign 12v circuit for the exciter plug. Installed a 470 ohm 1/2 watt resistor on said circuit. Installed a new weatherpac connector at the alternator.
On first start up, it whent straight to 14v and stayed there for as long as I let the car warm up, which is until coolant temp reaches 160 ish. Drove a few miles to the gas station and noticed the Volt gauge eased it's way down to 13.5 ish. Same on the return trip home. Later in the evening I attended a family function which entails a 20 mile jaunt up the highway. Voltage was steady above 13 the entire way, except when I hit a red light at the off ramp. My gauge was showing 13 even as I idled there for a solid 90 seconds. Back up to 13.5 ish once I got rolling again.
similar story for the ride home. I did a 65mph-110 mph hit which didn't affect the readings on the V gauge. Not 100% sure my problem is fixed although 13v-13.5 won't leave me stranded. If it stays like this it will be satisfactory. A spare alternator will be in tow from now on however. I'll update any changes.
Wow do I feel like a goon. Nice Sunday morning cruise yielded my volt gauge showing this after a good 50 mile jaunt in varying driving conditions.
This time however it was still showing this when I got home. So I got the multi meter on it and found this.
This was with high beams on, high speed fans active, trans cooler fan on, hvac fan on. I'm beginning to think my gremlins are nothing more than a failing voltage gauge.
oh man! Now all I have to do is verify it's not a bad connection, but I have a feeling it's the gauge. I had faint, odd noises coming from that area a few weeks ago. I thought it was the tach. Anyhow, the first two alternators were definite failures. Alternators 3 and 4 I think may have just been my gauge playing tricks. Now if I can just find a matching gauge I think this fiasco will be behind me.
I think.
Maybe.
Hopefully.
Yeah, either that or figure out a "correction factor" to use.
The thought crossed my mine as well , but today the gauge failed showing 12v. I'm not sure how I would differentiate between gauge failure and alt failure while cruising down the road if it continues to fail displaying 12v.
Do not judge alternator and charging health based off of a secondary voltage reading from the interior harness. Most of the time they read at least a half a volt low compared to a direct reading at the battery.
The used alternator and a new used plug from another harness cured my check gauges light that would occasionally come on.
So when in doubt use a volt meter to check voltage at the battery
Last edited by chrysler kid; 08-21-2017 at 06:49 PM.
It's just running off of a secondary interior harness voltage wire it can read .5 bolts low compared to the dash gauge and the volt readings on a radar detector.
The used alternator and a new used plug from another harness cured my check gauges light that would occasionally come on.
So when in doubt use a volt meter to check voltage at the battery
Correct, for the best reading tap in at the alternator or battery. But you'll need a switch on it or it'll constantly be on.
And never trust your gauge, always use a volt meter to verify.
Glad things are getting better for both of you
Last edited by 00pooterSS; 08-22-2017 at 05:25 PM.
All good points for sure. What tripped me up in this ordeal is that my first two alternators actually DID fail. And the gauge has always been dead nuts accurate for the 20 years that I've owned it. Unfortunately for me, it failed when I was having charging issues and I made a rookie mistake by overlooking it.
All good points for sure. What tripped me up in this ordeal is that my first two alternators actually DID fail. And the gauge has always been dead nuts accurate for the 20 years that I've owned it. Unfortunately for me, it failed when I was having charging issues and I made a rookie mistake by overlooking it.
You won't be the first or last to get tangled up in that man. I bet you will break out the meter out of habit going forward, it's how we all learned lol. I've been bitten by the same kind of **** many times, and it's currently why I'm looking for a digital volt gauge for my boat. I already moved the feed wire for the gauge from the instrument cluster wiring to the main feed wire from the battery. They had the volt gauge connected to the power wire that fed all gauges and light so every time you turned something on the voltage read lower. Dumb way to wire it.
Moving the wire improved my readings, but it still gets funky and the gauge is 26 years old.. When the gauge shows 12, I show over 13 at the battery with a meter. Regardless, it never stops making me worry while out on the water.
If only things were built well and worked properly.. Sad we can't just have that. I irritates the **** out of me that pretty much everything is junk these days.
They had the volt gauge connected to the power wire that fed all gauges and light so every time you turned something on the voltage read lower. Dumb way to wire it.
Moving the wire improved my readings, but it still gets funky and the gauge is 26 years old.. When the gauge shows 12, I show over 13 at the battery with a meter. Regardless, it never stops making me worry while out on the water.
I'm going to use the dedicated ign 12v I used to power the resistered alternator exciter circuit for the V gauge and the V gauge only. Going to plug the pcm back in for excitation duties. I'm not 100% my V gauge is bad, it could be getting dirty signal. It's one or the other though.
I'm going to use the dedicated ign 12v I used to power the resistered alternator exciter circuit for the V gauge and the V gauge only. Going to plug the pcm back in for excitation duties. I'm not 100% my V gauge is bad, it could be getting dirty signal. It's one or the other though.
I like that plan better, a pcm controlled alt will have less 100% fielding time than if it's wired to be 100% all the time (straight 12v to alt). So that alone should help the life of the alt.
And yep sounds like you're on the right path with the gauge too.
08-15-2017, 10:45 PM
, but today the gauge failed showing 12v. I'm not sure how I would differentiate between gauge failure and alt failure while cruising down the road if it continues to fail displaying 12v. 
