Strange charging question
Thread Starter
Teching In
Joined: Mar 2002
Posts: 5
Likes: 0
From: Austin, TX
Strange charging question Car has new batt and alt, and right after each one was installed it was reading about 13.0-13.4 at the batt(which was low due to bad alternater and still having to charge up). But after a couple days of driving around the gauge suddenly fell back down to 10 and is having the same problem again. Car is not mine, just a friend who lived about 50miles south of me. Going down there to take a look at it but need some ideas as to what to check for so I know what tools to bring. Possibly the power wire for the alt is loose, but not sure on that one. Posative battery cable gets warmer than normal at the terminal after a little use. Also says he blinkers are starting to slow down for some reason. 
Just looking for a few good ideas, hangover is keeping me from coming up with my own.
Just looking for a few good ideas, hangover is keeping me from coming up with my own.
On The Tree
Joined: Sep 2006
Posts: 142
Likes: 0
From: Colorado
Could be the charging system is goin out. More than just the alternator and battery. Could be a short in the wires. Could be a few things. It could be a defective alternator. There are out of the box failures. Especially if it was bought at Auto Zone. Most electrical devices from there either don't work at all, don't work right or die within a matter of days after purchase...
does he mostly to city driving?.. could be that he needs an underdrive pulley for the alternator to give off more amps, do an alternator test and see if its within specs....pretty sure it should read 30-40 amps at idle.
Thread Starter
Teching In
Joined: Mar 2002
Posts: 5
Likes: 0
From: Austin, TX
Most of the driving is around town, but made the drive from austin to san marcos to help put a charge on it. Plus the batt had a full charge on it when I installed it. Where on the PCM do I do this test?
And is it possible to get some tool combo on the power wire for the alt w/o having to remove it? Not sure if a 13mm on a 1/4 ratchet would do it or not...
And on a side note...lol at my join date and post count
And is it possible to get some tool combo on the power wire for the alt w/o having to remove it? Not sure if a 13mm on a 1/4 ratchet would do it or not...
And on a side note...lol at my join date and post count
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Measure charging system voltage at the battery while running. Measure the charging system voltage at the alternator and/or starter terminal while running. If there is a 1/2 volt difference or greater, replace the positive battery cable.
Thank you for posting make and model of vehicle BTW.
Thank you for posting make and model of vehicle BTW.
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Originally Posted by Marc 85Z28
Measure charging system voltage at the battery while running. Measure the charging system voltage at the alternator and/or starter terminal while running. If there is a 1/2 volt difference or greater, replace the positive battery cable.
Thank you for posting make and model of vehicle BTW.
Thank you for posting make and model of vehicle BTW.
Originally Posted by 98trans-am
im not sure if i really get what you mean by seeing a voltage drop, because even a wire adds resistance to a circuit but it could be im just not reading it right.