alternator problem

[evilbender]

ok so here it is, my truck's (720) battery wasnt holding charge, so i thought it would be the alternator. i replaced the alternator and the battery light is still on and the car dies when i take the battery cable out.

 

also whats up with that little solenoid on the alternator? and a little black cable that wasnt hooked up to anything.

 

i get tit that the alternator isnt getting power? i havent checked the voltage yet, but just wanted to know if this is common the the 720 trucks and anyone have any advice on this matter. thanks.

[skunk]

where did you get the replacement alt from?

are you sure the one you put in is good?

Iv had to exchange "re-built" alts like 4 times in one day until i got a good one.

[evilbender]

i got the alternator form advanced. i am not certain. but do you know what the solenoid looking thing is on the old alternator? and black wire just hanging.?

[nismo dr]

i've never seen a solenoid on an alternator, if your talking about the capacitor, I believe its to reduce interference with the stereo

[evilbender]

yea its like a little capicator/solenoid thing on the ground side. and there is a black wire that connects to nothing there as well.? ontop of another fatter black wire that goes into the harness

[datzenmike]

ok so here it is, my truck's (720) battery wasnt holding charge, so i thought it would be the alternator. i replaced the alternator and the battery light is still on and the car dies when i take the battery cable out.

 

also whats up with that little solenoid on the alternator? and a little black cable that wasnt hooked up to anything.

 

i get tit that the alternator isnt getting power? i havent checked the voltage yet, but just wanted to know if this is common the the 720 trucks and anyone have any advice on this matter. thanks.

 

First stop throwing money and parts at it. You may have paid for an alternator you didn't need.

 

I take it that recently the red charge light came on??? and you started having battery problems a day or two later???

 

 

Two things will turn the light on:

 

No alt. output

bad battery

 

Well as you have changed the alt. I can assume the plug is in tight and the connections clean and tight on it. If we assume the alt is OK then perhaps it isn't getting a signal to charge. The alt is connected to the positive side of the battery through a fusible link. If this link is blown there is no 12 volt source to get the alt charging in the first place.

 

There are 3 fusible links on the 720 a Black and two Green ones and they are located very near to, or attached to the positive battery post. There will be a plastic connector with the three fusible links with one Black and one Green going to a double connector and the other Green going to a separate single plug in connector. Check them all but I think it's the Black one that's the problem. Fusible links are about 3-4" long and may look OK but be burnt out internally. Additionally the connections may simply be corroded or loose and not conducting.

[evilbender]

hey mike you were right the black wire was burnt out.

when i cheked the continuity it was good but the wire is broken.

would it be good if i sodered a new wire between the broken links or is there a place where i can buy a whole new shit? i dont know if autozone/advanced sells em. thanks.

 

also what is that wire? signal wire for the alternator to turn on?

[datzenmike]

It needs to be a special piece of wire called a fusible link and cut about the same length. Black is an 80 amp rating so get the equivalent from autozone and solder it in. The dealer may have one or a wrecking yard.

 

It acts just like a fuse but is much slower to blow and can handle sudden but temporary heavy loads without blowing unlike a fuse. In the event of an accident where heavy cables short out it will burn out and prevent a fire..

[evilbender]

ye ai have a piece of wire as a temp to get around, and ill go do that tomorrow, but thanks a lot man!