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Re: alternator not charging
Check for voltage with a multi meter or volt guage most of the GM trigger wires come from the computer and are only 5 volts. 5 volts is not enough to light some test lights. If still nothing the problem is probably the computer. But it can be manually excited. The two terminals in the alternator on the left of the pigtail (when looking from the front of the van) need + power. the far left is the trigger wire the one next to it is ignition power.
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Could be the circuit from the key that tells the alternator to energize.
You may have a 10amp fuse marked GEN that could be blown, and there could be a problem with the body or engine computer which controls the internal voltage regulator. You may need a shop manual to get the test procedures.
Did you check the fuse in the under hood fuse box ? GEN / BATT fuse 10amp . Is your check engine light on ? This is a computer controlled charging system , it should have four wires connected to the alternator . 1 - the heavier wire on the back ,this comes fro the starter - the one with fusible link , you could have checked for battery voltage with voltmeter ! The three other wires in the connector are the orange one ,this comes from the GEN / BATT fuse an should have battery voltage ! The last two come from the PCM - engine computer . The gray wire is the turn on signal from the PCM an the Red wire is the control from PCM ! Charging System Wiring DiagramMOTOR Magazine Article MOTOR Information Systems
First make sure your batt connections are good then check the power wire onthe back of the alt make sure you have power then use multi meter start vehicle and measure the voltage across the batt. Then rev the eng 2000 rpm and it should be around 14 to 14.5 volts
There is a fuse or fuseable link between the alt and battery, and the alt gets a signal from the key to activate the voltage regulator. I would check for batt voltage at the alternator and you may need a wiring diagram to check for key voltage.
u need to chek for batt volts at the pos pole on the bak of alt.should b batt voltage if not then wire from pos pole on back of alternator to battery could be broken,causing no output tobattery. wiggl voltage regulator wires while engine runs an check volts with a voltmeter to see if it jumps to over 13v wen wiggling connector.also chek fuses an fusible links for continuity.
Yes, If you have a volt meter, jump and start engine, with engine running you should have approx 13.5 to 14.2volts that would tell me that batt is getting charged when engine is running. you said new batt would not hold a charge, I would be thinking about a parasitic draw(small amount of power) that in time will drain batt. things to look for are glove box lights, under hood lights that dont turn off. one easy way too see if you have a draw is to disconnect one batt cable, now use a regular (12volt non-self powered) test light and touch one end to batt cable and the other to empty batt terminal, with no light switches on and doors closed, this test light should not light and if it does then you have a drain on batt that will kill it say overnight.
There must be a wiring problem or defective alternator, check all connections to battery and alternator also make sure to check the fuses, check for a bad fuse under the hood fuse box and also make sure the connections are good, there are fusible links on the alt or battery, check the power wire from alt to battery and then the small plug going to alternator,
1) check 10A fuse in the batt. juction box (eng. comp.) hot at all times.
2) check the large red battery wire to the alt. for good conn.
3) make sure the alt. is grounded properly
4) gray wire sent from the alt. to the PCM
5) blue wire sent from the PCM to the regulator (alt.)
6) small red wire power frorm the 10A fuse
if all checks out and still not charge replace the alt.