Car will not charge!!!!
07-15-2014, 10:15 PM
#1
Car will not charge!!!! heres the backstory....i was driving on the highway and my voltage slowly started dropping until my car died. ive replaced the alternatory, battery, and even the battery cable that runs to the alt, starter, and junction box. the exciter wire clip with the car running read 9.6 volts. before my car was well above 13V but i cannot get it above 12V now and even then it still steadily drops voltage until itll eventually die. im sooooo lost at this point. i even put a friends alt and bettery out of his camaro and put it in mine and still no luck
07-15-2014, 10:26 PM
#2
Check all your ground wires. I had a similar problem on a tractor I would mow a 20 acre field with. The voltage would just drop and drop. Turned out to be the battery to body ground was loose and corroded.
Last edited by TX98Z28; 07-15-2014 at 10:31 PM.
07-16-2014, 10:03 AM
#4
for 1999 to 2002 the one wire going to the alternator into the 4 pin plug, known as the exciter wire, is called out in the service manual as the generator turn on signal. The pcm according to the service manual puts 5 volts on this wire which is connected to the alternator voltage regulator. the regulator which is a microprocessor or ASIC (mini computer) sees this then does it's thing and the alternator outputs current on the large output terminal.
for 1998 i've read that the pcm sent 12 volts on that exciter wire, whether or not it matters at the alternator voltage regulator i don't know- i suspect because alternator part #'s are the same among all years now that as long as the regulator sees 5 volts or greater it recognizes it as a turn on signal from the pcm and 12-14 volts won't hurt it. when the alternator voltage regulator fails, it will connect that exciter wire to ground, the pcm sees this and is how it knows alternator failure and sets DTC.
the pcm monitors system voltage however else- with any of the power feeds to it- and does not monitor system voltage or battery voltage on the exciter wire to the alternator.
so all that said you need a tech2 or other handheld that will first verify the pcm is commanding the alternator to charge, don't chase your tail too much on other things not knowing if the pcm isn't commanding the alternator to charge. worst case you have a bad pcm, or you rig something to put 5 volts on that wire to the voltage regulator. from there check all your grounds obviously, and battery cables. there's one thin ground wire from the alternator area to the body, can't remember if it was a stud on the alternator shell or not. and check your output wire from the alternator to wherever it goes to, the underhood fuse box bus bar i think, i don't believe it's fused but look for an inline fuseable link on the wire itself.
for 1998 i've read that the pcm sent 12 volts on that exciter wire, whether or not it matters at the alternator voltage regulator i don't know- i suspect because alternator part #'s are the same among all years now that as long as the regulator sees 5 volts or greater it recognizes it as a turn on signal from the pcm and 12-14 volts won't hurt it. when the alternator voltage regulator fails, it will connect that exciter wire to ground, the pcm sees this and is how it knows alternator failure and sets DTC.
the pcm monitors system voltage however else- with any of the power feeds to it- and does not monitor system voltage or battery voltage on the exciter wire to the alternator.
so all that said you need a tech2 or other handheld that will first verify the pcm is commanding the alternator to charge, don't chase your tail too much on other things not knowing if the pcm isn't commanding the alternator to charge. worst case you have a bad pcm, or you rig something to put 5 volts on that wire to the voltage regulator. from there check all your grounds obviously, and battery cables. there's one thin ground wire from the alternator area to the body, can't remember if it was a stud on the alternator shell or not. and check your output wire from the alternator to wherever it goes to, the underhood fuse box bus bar i think, i don't believe it's fused but look for an inline fuseable link on the wire itself.