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93 mx3 Electrical problem- alternator not charging/ powering car
Hey!
A few days ago i woke up an my battery was completely dead. She was driving perfectly about 5 hrs before this. I though the lights were left on so I got her jumped and she started fine. The AA guy did a few checks and my battery was good but charge coming in was low and my alternator was crazy hot. Once we turned off the car something was pulling a serious charge (more than my lights being on) from the battery and this was being reflected back at the alternator. I couldn't source another alternator but there was an mx3 near me for sale for cheap (body and a bit of the interior were wrecked from mold) she was sitting for a year. got her fired up with my battery out of my other mx3 and drove it home- it charge my battery no problem. We then went and swapped alternators and she ran fine (this was only on the fully charged battery though) for a bit and then all electronics dropped and she stop. She doesn't seem to be pulling a charge when off anymore as there is a bit of life in her still (was totally out of juice before cz there were no dash lights). but she isn't being charge and because she died in mid drive i believe the alternator isn't supplying power either. Anyone have any idea what is going on here :confused: or had this problem before. Thanks for all your help |
Do you have a multimeter?
Your first alternator died. But we don't know why. Possible reasons: 1. it was at the end of the lifespan anyway. 2. too much resitance somewhere: ground connection, cable to the battery, battery itself. 3. there is short to ground somewhere. That drains the battery and the alternator can't keep up recharging and eventually fries. You have to get a haynes manual of a Mx 3 or a protege of that vintage for wiring diagrams and meter values. Then you can check the cables for resistance and so on. |
thanks for the reply.
It didn't die as such.. i think the rectifier went but the alternator has been in her from the star (so 20 years old now & 217k kms) and it was getting hotter than the head... so i believe it was on its last leg). I feel like something might have over worked it. We did a check and if my heater, radio and lights are on the drain was more than the alternator. (this would have been the case the last time a drove her) I have a multimeter... is there things you would suggest I check. I feel like there is a short somewhere but im not too sure where to start or want i need to check. Someone i know says that because my battery died my alternator is struggling to charge it from empty, electric pull is too much to charge it and power the car.... is this something? |
Originally Posted by SeanSpooky
(Post 136157)
thanks for the reply.
It didn't die as such.. i think the rectifier went but the alternator has been in her from the star (so 20 years old now & 217k kms) and it was getting hotter than the head... so i believe it was on its last leg). I agree. At that age and mileage it has done its job. The alternator does not have a rectifier per se. It has a voltage regulator and diodes to keep the output in range. My first suggestion is removing the alternator and the battery to take the pieces to a parts store for free testing. O'Reilly's tend to offer good quality remanufactured parts. Auto Zone's remanufactured electrics are suspect. If the parts are deemed good we have to look further into the car's wiring and consumers of electricity. I feel like something might have over worked it. We did a check and if my heater, radio and lights are on the drain was more than the alternator. (this would have been the case the last time a drove her) Yes, it got overworked. but was it overworked because a diode burned out or a winding shorted out making it too weak or was it overworked because something went awry in the cars wiring or a particular electric devise? Testing the alternator and the battery at O'Reilly's will answer that question. Also:check the fuses. If the fault is in the wiring you should have blown fuse. I have a multimeter... is there things you would suggest I check. I feel like there is a short somewhere but im not too sure where to start or want i need to check. Until you are sure you have a good alternator and battery it makes little sense to go on a hunt. But you can clean contacts, diconnect, inspect and reconnect wiring harnesses, look for chafed wires and so on. Again, I would expect a blown fuse if something were that bad. Look for ground straps and clean their contact surfaces. All that cleaning could help lowering resistance that may have developed over time. Someone i know says that because my battery died my alternator is struggling to charge it from empty, electric pull is too much to charge it and power the car.... is this something? Again, testing the equipment will tell. And google for "how to do a voltage drop test". Google for: wiki alternator After that you will know a lot more and you will be more confident about fixing your MX3. |
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