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Tech501
Tech501, Auto Service Technician
Category: Car
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Experience:  38 years exp, ASE Mastertech with L1 Advanced Engine performance
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1992 mazda protege: main relay..jumper cables..reads..same voltage

Customer Question

my 1992 mazda protege has a charging problem Ireplaced the battery and alternator,which both checked good and also replaced the main relay. the battery just drains slowly as soon as I take the jumper cables off and the alternator only reads the same voltage as the battery on all legs.im running out of ideas the book has nothing about this please help.
Submitted: 11 years ago.
Category: Car
Expert:  Marc replied 11 years ago.
 

Protege's and 323 have a fusable link coming of the back of the alternator. It's the big thick wire the conection on the alternator should be hot at all times if not the fusable link is bad. And needs to be changed.
Customer: replied 11 years ago.
Reply to enginboy's Post: Ive checked for a fusable link in all wires couldnt find one, there is a 80amp on the thick wire in the fuse box, I removed all the wire casing and also did continuity check on all wires they make contact in the fuse box and they all checked good , I can jump start the car just fine and the battery will take a charge.and all three wires on the alternator read the battery voltage when i remove the other car off the circuit i can watch the battery go slowly from 12v to about 6 when it dies. if i charge the battery i can drive for a short distance maybe 10 miles. i hope this can help
Expert:  Tech501 replied 11 years ago.
 Do you have battery voltage at the large terminal of the alternator with the engine off?
Customer: replied 11 years ago.
Reply to Tech501's Post: Yes it reads battery voltage all the time
Expert:  Tech501 replied 11 years ago.
 The means the fuse is good. That only leaves the alternator or it's wiring to be bad.
Customer: replied 11 years ago.
Reply to Tech501's Post: The wiring looks good and ive already changed the alternator 3 times from 2 diffrent stores kragen and autozone and all of them still tested good.Plus all of them having the same problem I dont know
Customer: replied 11 years ago.
i went threw the wires throughly last night i even took off the protection casing to look
Expert:  Tech501 replied 11 years ago.
 Your charging system is not keeping with with your car's consumption. Either the consumption is too high or the charging system is too low. Simple as that. Now you need to find out which and why.
Customer: replied 11 years ago.
I cant get anything out of the charging system the voltage only goes down matching the battery if i remove the big wire i get nothing at the conection on the alternator
Customer: replied 11 years ago.
the other two wires still read battery voltage with the big wire pulled
Expert:  Tech501 replied 11 years ago.

Quick question, Does the charge indicater light come on when the key is turned on? That goes the Wht/Blk wire at the alternator and is fed by a 15A meter fuse. The Blk/Wht is powered by the 30A fuel injection fuse and the Wht/Grn is powered by the 80A main fuse. You really need to have this charging system tested with a VAT tester to check voltage, peak amperage and the diodes to find out exactly how that alternator is perrforming.. Your shooting blindly here.

Expert:  Joe Barcus replied 11 years ago.
with car running remove one cable from battery see if car still runs, if not then yes its not charging, if it still runs then you have a short in the field place a amp clamp on the battery start pulling fuses until you see it go away, then track that area.
Expert:  Tech501 replied 11 years ago.
 Removing a battery cable from a working alternator can damage the alternator.
Expert:  Joe Barcus replied 11 years ago.
can but in most case's not. besides this will break it down where to take off from if you dont have a meter. should be 13.8 volts running. still remove of a cable for 10 secs wont hurt a thing. just my opinion is all here and owner do as you feel.
Expert:  Tech501 replied 11 years ago.

 


 Alternator Precautions
Mazda 323/MX-3/626/MX-6/Millenia/Protégé 1990-1998


 Several precautions must be observed with alternator equipped vehicles to avoid damage to the unit.


 


  Never separate the alternator on an open circuit. Make sure all connections within the circuit are clean and tight.


The rest of the article and precautions can be read here


http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/14/3e/c5/0900823d80143ec5.jsp


Customer: replied 11 years ago.
The charging lamp does come on and if i remove the battery it dies as soon as i pull cable
Expert:  jon_050 replied 11 years ago.
 Don't do that again! If you don't care about the damage the voltage spike can cause.... You don't want to see the flash of a battery exploding.
Expert:  Joe Barcus replied 11 years ago.
no doubt then its in the charging and no shorts draining the battery. good thing from here would be get a wiring for the charging system most dealers will copy that for you for a low charge. track the charging system that way. going to be a burned wire somewhere. or very well could be a bad new alternator. seen it 1000 times.
Expert:  Tech501 replied 11 years ago.

 Here's your schematic but I've already described everything on it.


Expert:  Joe Barcus replied 11 years ago.
TECH 501 has done a fine job of providing the specs for what you need. now with a little knowledge and a fused jumper wire you could find your trouble by using the jumper wire find the broXXXXX XXXXXne. I feel that tech 501 has earned the 10.00 well. for these specs alone would cost you that. good luck
Customer: replied 11 years ago.
Ok ive jumpered everthing and i can get 16v from alternator but as soon as i touch the battery it starts draining stepping on the gas draws more voltage everything goes dimm i also checked for ground to the hot i had ground going to a 10 amp fuse marked room but even pulling this it still draws any more ideas
Expert:  Tech501 replied 11 years ago.
Look Dwayne, you don't understand electrical circuits well enough to diagnose this. You need to take it to a shop.

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