Protege alternator problems
 

Hey guys

My wife's 2001 protege 2.0l is experiencing some problems. The original alternator seized up and shredded the belt. I bought a remanufactured alt and replaced the belt. After install, the battery light turned on. I checked the voltage at the battery and it was 16.99v on a fully charged battery. I took it back and had it tested and it was bad. I swapped out for another and installed it and the same thing happened with the battery light and high voltage. This round the alt was checked prior to bringing it home.

I only ran the engine for 45 seconds or so on the second alt. The alt got so hot, you couldn't keep your hand on it. I took it back off and had it tested again. It tested fine again.

There are no previous signs of overcharging at the battery. I had a theory that the original alt failed due to this heat I am seeing on the new one. Any thoughts?

Sounds like a faulty voltage regulator. The Alternator is probably full fielding aka working at its hardest.

Most of the time, the voltage regulator is built into the alternator, so you may need to try another alternator again and maybe consider a different brand or a new one.

Edit: reading the end, the alternator is going to get hot. Thats normal. If you have a multimeter, check the voltage while the car is running. It should read 13.2 - 14.2 volts. If thats the case, everything sounds normal to me

The second replacement alternator was giving me a reading of 18v at the battery. When run on their alternator tester, it read 15.2 tops.

Both of those voltages are considerably higher than what they should be. I would see if the alternator you bought has a warranty (most reman's do) and get a another. Even when your alternator is working at its hardest, it shouldnt be near 15v, as far as I am concerned. And 18v at the battery is dangerous. A fully charged battery is 12.6v. Someone def isnt right with your setup.

What I am having a hard time understanding is why two different readings. From what I am reading, the PCM controls the alternator. It is believeable that if something went wrong with the PCM and it sends a signal to the alt to max out, I would get the current condition. Why would it suddenly do this at the exact same time the original fails? Could it be that is the reason the original failed? I see no evidence of an overcharging condition at the battery.

From what I remember from my schooling, the pcm dictates the how hard the alternator works based on the needs of supporting the electrical load in the vehicle. For example, if you have your stereo, a/c, lights, blower motor, ect. All working at the same time, the pcm will tell the alternator, "hey work harder, we need it." but when there isnt a need for heavy loads as such, the alternator shouldnt be working nutso trying provide the electrical energy it needs.

This is all processed through the voltage regulator in the alternator too. Once the voltage ragulator gets the message from the pcm that it needs to provide more or less enegry, it does so. But if the regulator has gone haywire, which is common, it will often times, do the opposite of what the vehicles needs, ie. Provide way more enegry, or not enough.

If you are getting over 15v from the alternator, to me, it sounds like the regulator has gone haywire, but there is a way to test this, called full fielding. Its model specific but idk if ours cars has it. May be worth reserching. In the mean time, have you checked this video out? May help you if your diagnosis.

#/watch?v=FTGz0PKIl84

Awesome vid. So the 15.2 that was read at the parts store falls within the his range of good. I was thinking it sounded high also. It was suggested to me on another forum to take a real good look at the battery. I am going to test it under load and see what happens. It makes sense, battery tests good with no load and fails under load resulting in the alternator working overtime to keep up.

No go on the battery. Replaced with a new one and same outcome. Also checked grounds and all the pulleys for bind. Anything else?

Replaced with a different brand alternator and all is good. Must be a bad run from that manufacturer.

Good to hear man. Ya sometimes you just get that dud. At least its working now :)

remanufactered alternators are hit and miss. you must keep replacing them until you get one with a working regulator--which are often not replaced during rebuilding.

Thanks guys. That is a frustrating procedure. At least now, I am pretty quick with alternator removal/installation on that car.

Next time i'd suggest just taking it to a local alternator rebuilding place (they do exist). I've had a hell of a time getting working alternators for my daily driver, and i'm seeing increasingly frequent reports of people having to swap out 3 or even 4 alternators before getting a working one.