Amagi82

How to you test to make sure the alternator is working correctly? I'm concerned I may have damaged it.

rotary emotions

if it's on the car a simple voltmeter should work fine to see the output under several rpm. A handheld voltmeter will sure be more accurate then that thingie Mazda gave us in the dash.
if it's out, you can test several things, best check your manual, if you do not have one, now 's a good time to buy one
Anyway, here's some help: assume it is not in the car. Dissasamble it, and do following tests:
-check rotor coil for damage. Measure resistance between the two slip rings. Must be between 2.0 and 2.6 okm. If not, Mazda claims you should replace the rotor (which means: get another alternator!)
-check grounding of coil. check for continuity between slip ring and core There should not be any continuity. If so see above...
-Check the slip rings, they might be a little rough, if so: use fine sandpaper to get them smooth.
-Check stator coil for wiring damage: Check continuity between stator coil leads. If no continuity excists: replace stator...
-Check stator coil grounding: Check for continuity between stator coil leads and core. There must be none. Replace if there is continuity.
Now the alternator is checked for the main stuff. Don't forget to check the brushes, and/or replace them if needed. Of course you will also take a look at the bearings.
When you're at it, also see if the diodes work correctly. The continuity should only be in the correct direction.
So, did that help? Sure hope so!

RotorMotorDriver

iTrader: (1)

If its in the car, and it has an internal voltage regulator start it and let it idle. It should put out good voltage (mine is 13.5 volts all the time). Put a voltmeter on the prong on the back that charges the battery (the big one with the nut), and groud it to the alternator housing or some good ground. Read the voltage. You could also blip the throttle a few times to see if the voltage changes and turn on accessories and see if it changes signifigantly. If its not in the car, take it to an autoparts store that does free electrical testing .

~T.J.

Amagi82

alrighty, cool, I'll try testing it out once i wake up this afternoon.

13B4port

easiest way i have found if your battery light is on is to go to the back of the alternator and unplug the wire harrness but leave the single power wire still pluged in. go look at the battery light and if it's still on then it's not the alternator. if it shuts off then the alternator is the problem. the reason this works is because the light turns on when the circuit is closed. thats why the lights on when you put the key in put don't turn the car on. when you start the car, the alternator will open the circuit and in so turning off the light. plz note this only will work if your battery light is on when your car is running. a lot easier than running around with a tester. but if the light stays on then you have to run around with the tester anyways.

web777

Just start the car and unplug the battery. If the engine shuts off then the alternator is bad.

inittab

stick your tongue to the leads.

BTW, never do that to your DSL twisted cooper lines. I know someone who recently did that and now he knows what 50+ volts feels like. I think he's just starting to taste foods again. LOL

fatboy7

Don't don't lick the phone wire when the telephone is ringing. Its normally 28V, but when the phone rings, it jumps to around 80V. Ouch !!

As far as the alternator is conserned, do like has been said, start with the easy stuff. Look at the onboard Voltmeter, does it change much when you rev (it should get a little higher maybe,but never lower)? Does it read around 13.5-14.5V? If its too high, then you've got a bad regulator(and should fix it/turn off the car immediately, otherwise you could burn up your ignitors, and coils), if its 12.8 or so, your running off the battery (and the dummy light should come on).

If everything checks out in this regard, try what web777 suggested, and pull the negative terminal off the battery while the engine is running, just make sure you pull quickly, and in an open (good ventalation) area. Your bound to get some sparks, and batterys leak of hydrogen as they age, which could explode. Hydrogen is much lighter than air so, especially in an open enviroment, its not much an issue. the alternator may make some power, but if bad may not be enough without help from the battery. Once the battery is removed from the equation, turn on all the accesories: radio, heat, lights, AC, you name it. If the car dies, you should have the alternator checked at a local parts shop, they do it for free.

IMO, opening up the alternator is too much a PITA.

FuLLsMoKe

Who licks telephone wires?

Manntis

The same people who ran around licking stuff until they discovered that licking certain frogs gets you high... I shudder to think what things they licked before stumbling across that knowledge.

Amagi82

lol @ some of you


Well, the alternator is toast I believe. I started her up, and measured the voltage: 11.5 volts. revved it up: 11.4 volts let it idle: 11.3 volts once the engine warmed up, i measured it again: 10.5 volts. In other words, no working alternator and the battery is hurting. Crap.

fatboy7

hehe....

Your mouth makes a good third hand, unfortuately its also not compatible with live wires......

So on that 'charge' I plead the 5th

I'd say your right..... stick a fork in it, 'cause it's done.