Replaced Alternator, No Charge, Dash Lights On

[monteburns]

Hi All,
Just went through my first time changing my alternator on my 100. Here's the story:

Alternator has been whining/groaning for over a year now, so I figured the time was coming to replace it. The other night, started the Cruiser and the battery light came on. Lights seemed kinda dim, so it seemed my time had come. Voltmeter on the battery while running was at 11 volts, leading me to conclude it was time to swap the alternator.

Went ahead and purchased a remanned Denso from Amazon (https://www.amazon.com/gp/product/B000C5WBRS/ref=oh_aui_detailpage_o06_s01?ie=UTF8&psc=1)
The body seemed just a bit smaller but otherwise it was a normal fit.
After getting it all installed and taking it for a test run, within a half mile all the dash lights lit up and the lights started to dim. Barely got it turned around and back home before it started to stall out. Now it's all worse than before! Voltage at battery while idling dropped to 7 (super low).

The only thing of note is that it was a PAIN to get the wire plug out. It was stuck in there and took some prying to get out. It seemed the wires were short enough that they were stressed a lot, but none seemed to be to broken from the terminal.

Also, one, the one harness that is anchored to the passenger side I did not re-attached because there wan't a location on the new alternator to do so.

I'm now not sure where to begin diagnosing. Any help would be appreciated greatly.

 

[CloudCity]

Wiring harnesses are pretty rugged by design but anything is possible on an old rig, there could be an internal separation between the wire and it's pin inside the connector.
I assume you're going to pull it back out to diagnose so test it or take it to Autozone or your favorite garage and have them test it for you to be sure it's not a faulty unit. Remanufactured can have issues sometimes. If it checks out that might point to the harness as said above.
I'm not sure what fuse could be involved, if any, but always a good idea to make sure you didn't pop something on accident.

 

[monteburns]

Follow up: I went back and started it up about an hour later. Started without issue, maybe slightly sluggish but not bad, idled great, NO dash lights at all. So I threw a volt meter on the battery while idling and it’s starting reading was 11.8 volts, still low but higher than when I left it. As the engine continued to run, the voltage dropped and dropped. It was like watching a countdown clock. As I increased the RPMs the voltage would drop faster, until it reached around 8 volts and would start to stutter. However, no dash lights ever came back on.

 

[monteburns]

I should have noted:
2000 w 133k miles

 

[Eicca]

I bet the voltage drop was just because the battery was the only thing powering the engine.

Sitting for long enough while you swapped alternators probably gave it time to recoup a little bit of voltage. Batteries do that.

 

[whitey45]

Junk rebuild is my guess, throw a good alternator on and make sure the battery is fully charged.

 

[kruisinkid]

There is a 140A fuse for the alternator in that little box attached to the positive terminal of battery. Make sure it looks clean and not corroded in any way. There is also a small 7.5 amp fuse labeled alt-s in the fusible link box. Check both

 

[shevy77]

Also, one, the one harness that is anchored to the passenger side I did not re-attached because there wan't a location on the new alternator to do so.

I think this statement means that you didn't use an anchor point, but you were able to connect the connector, correct? If it means the connector was not connected, that would be a problem.

 

[monteburns]

I think this statement means that you didn't use an anchor point, but you were able to connect the connector, correct? If it means the connector was not connected, that would be a problem.

Correct, it was not an unplugged harness, simply that wire bundle that passes by the alternator. Checked it again today, same issue. No dash lights at all (again) but zero charge to battery.

 

[chukstel]

I got same issues some years back, replaced 3 remanufactured/repair alternators and it did not work.

The solution was buying a brand new alternator and problem solved. Still using it more than four years now.

 

[chukstel]

Like kruinkid said, make sure those fuses are OK first.

 

[hoser]

New Toyota/Denso alternators are near unibtanium nowadays.

 

[Eicca]

I got same issues some years back, replaced 3 remanufactured/repair alternators and it did not work.

The solution was buying a brand new alternator and problem solved. Still using it more than four years now.

That's what it ended up being. I was helping @monteburns investigate and then I remembered I had an old but working alternator in my trunk for backup. Popped that in and it was back to normal, so I believe he sent the reman crap back and somehow found a Toyota unit.