Brand new ALT, brand new BATT. (got them today) but I'm only running 12 volts with car on. When you unplug the battery everything dies. So I'm not getting juice from the alt to the batt. Please give me suggestions to check.
of course everthing will die when you unplug the battery.
how did you check how many volts you get?
Gilles
2.3 Ho
if the alternator is running right you shouldnt need the battery , hook a multimeter digital on 12volts to the alternator connectiosn see if the alternator itself is charging could be bad wiring or something.
Alternators have an internal voltage regulator. If it's not reading that it's connected to a battery, the regulator won't send voltage out. Check the wires going to the alternator and make sure the alternator has a good ground to the block.
John Wilken
2002 Cavalier
2.2 Vin code 4
Auto
The alternator is not grounded. If both calbes on the battery are unplug, the car will stop since the electricity can't go anywhere. You can have 100 000volts but if you don't have any ground, it won't work. So YOU NEED THE BATTERY. Even if it's dead the car can run with the alternator BECAUSE there's a junction between the negative and the positive pole.
Gilles
2.3 Ho
UNPLUGGING THE BATTERY?
The old idea from years back does not work on new computerised systems, if you don't blow the alternator diodes you may damage the computer or accessories. The battery acts as a large surge suppressor.
I do hope not with the engine running or there goes another Alternator at least.
12volts does mean there is no output from the alternator, you are only reading battery voltage
If the battery was disconnected BEFORE the engine was started you have disconnected the source of power the ROTOR needs to energise and produce it's magnetic field, so there would be no output from the alternator.
1. The A/C fuse 25amp supplies the rotor in my '93 2.2 so you will have to ensure the fuse that supplies your rotor is good(If it's not the same one)
2. With the battery disconnected test the wire/cable from the BATT terminal of the alternator to the POSITIVE terminal of the battery, the resistance should be below 1 ohm to prove the wire is good.
3. Between the alternator and battery, in the cable run in 2. above, there is a FUSIBLE link in my'93, if you have one in yours it may have blown.
Buy an new one and replace it.
4. If that wire/cable is good, disconnect both ends of the negative earth/ground cable and ensure the cable has continuity and the cable ends and connecting surfaces are shiny clean.
Reconnect the earth wire to the chassis, all connections to the alternator, the fusible link and the battery.
a. Check the voltage at the battery terminals-should be about 12volts
b.Start the engine and check the voltage is 14-14.5 volts.
c. If the voltage is still only 12volts carefully check the voltage across the alternator BATT +ve terminal and battery negative, 14-14.5 volts here and the wire to the battery positive terminal/connection is still not good, 12volts or so and the alternator needs testing at a shop.
Hope this helps
Alont
Ya we had the old ALT tested at Autozone(roomate works ther, it's his car that's @!#$ up too) and the alt tested fine. But he decided to get a new alt anyways. His boss then gave him a new battery too. We insstalled everything ans it all LOOKS like it's on there right. We tested the battery and it runs 12volts, then we turned the car on and it's still tests at 12volts. Also he has an Auto Meter volt Meter gauge in is car. It has always read 14 when running the car. So i'm gonna try the suggestions and see if I can find a fuse.
