car: '99 Mazda Protege ES, 50,000 miles
Symptoms:
I could feel loss of power wihtout any rhyme or reason.
The idle would also drop and bounce back when I shift into reverse. On a hunch, I decided to check the electricals.
I used the Radioshack Battery&Alternator tester for this purpose.
What I found:
Somedays day the alternator is weak. Noticeable loss of power.
Other days it is fine. I feel no loss of power.
it is zoom zoom time.
How can I even take it to the Dealer.
Chances are it is going to show up fine on his meter. Then what?
Any ideas what is really wrong with the alternator?

Hank(BigH) indicated a Loose belt.

Anyone know how to check / tighten the alternator belt on the Pro ES?

How much tight should it be when Cold?

 

I'd suspect the voltage regulator, which I think is an internal one (inside the alternator). This should show up on a code check at the dealer, so if there's a problem, they'll know, even if the volts read ok.

I'm sure the shop manual has an actual deflection measurement for the serpentine belt, but there's a "ballpark" way to check. Find the longest run of the belt and try to twist it. If you can twist it more than about 1/4 turn, it's too loose. There isn't a tension adjustment; it's held in constant tension by a spring, so if the belt is too sloppy, it needs to be replaced.

Hope this helps.

 

i had similiar symptons but that was b/c i had a loose wire on my temp sensor.

 

There is a voltage regulator in the alternator, because I had mine rewound and they upgraded the one stock one.

 

2 my understanding, there are two regulators, one in the ecu and one is the alt itself. not sre how they work together or if one just monitors the voltage.

 

Either way, or even if it's a loose sensor wire, it should throw a code. Hook it up and let the OBD-II do its thing.

 

What do you mean "rewound?"

 

when you get a alt rewould, you are saying you got it rebuilt, usually uping the amp output of it

 

where is this located? is it reachable and fixable by hand?

tnx.

 

it is the sensor located in the air box. i had to resoder my wire into the sensor

 

my alternator had the same probelm. and the delaer replaced it under warranty. it died and caused the battery to have no charge. it was scary cuz i drove the 3 hrs from school to my house to go to the dealer.
arul