I had my alitnator checked and installed a new voltage regulator but the idiot light stays on.
2007-12-08 11:46:19 · 8 answers · asked by Randy R 1 in Cars & Transportation ➔ Maintenance & Repairs
Disconnect the ground wire from the battery while the car is running. If the car continues to run, the alternator is good.
If it shuts off the alternator "may" be bad. Check all the connections.
For all who gave me a thumbs down, look here:
http://www.wikihow.com/Check-an-Alternator
2007-12-08 11:50:59 · answer #1 · answered by Jason 6 · 1⤊ 5⤋
Measure the voltage, across the terminals of the battery, with the engine off. The no-load voltage, for a fully charged battery is 13.8 VDC. Measure it again, with the engine running. The voltage should be 14.0 VDC.
Turning on equipment, e.g., lights, heater, should not lower this reading, provided the engine idle is correct, and the belt is properly tensioned
The engine off reading, will be lower than 13.8 VDC, if the battery is not fully charged, or if there is an electrical load on the battery. Also, your meter may not be accurate, or properly calibrated. The important thing to look for, is the slight voltage increase, when the engine running.
It would be helpful, if you could make these measurements on one or more cars, you know are operating properly. It will give you confidence in the procedure, and your equipment.
Lastly, please make sure you are making good mechanical contact to the battery, with your meter probes. Good contact, is essential for a valid reading.
2007-12-08 12:18:08 · answer #2 · answered by Larry 4 · 0⤊ 0⤋
when the cars off it should read 12-point something volts....
start the car, rev it once a little
take another reading on the battery with the car idling. Is it higher by at least a volt or two? it should read in the 13 to 14-something range...
If not, bad alternator
if SO, its charging still.
I had a car that the light came on, but it was still charging, so I left it.still worked when I sold it two years later!
DO NOT DISCONNECT THE GROUND WIRE OF THE BATTERY, SURGES CAN RUIN THE CARS ECM (COMPUTER) as the battery kinda helps regulate the voltage surges...
2007-12-08 11:52:43 · answer #3 · answered by mdcbert 6 · 2⤊ 0⤋
Yes, Place multimeter on dc. Read voltage across battery terminals with out car running ,it should read about 12.5 volts . Now start the car and put leads across battery terminals . If it is reading anything above what the first reading was it is charging should being reading about 13.5 to 14.5. Also put the meter between ground and the power lead of the alternator on the alternator . It should read above 12.5 and eliminate the wiring betwwen the alternator and battery if faulty
2007-12-08 11:51:59 · answer #4 · answered by miiiikeee 5 · 0⤊ 0⤋
If you know how to use the multi-meter then you can set it to the low voltage scale that will measure a cars Charging Voltage then you will be able to determine the output of the system....
2007-12-08 11:51:02 · answer #5 · answered by RiverRat 5 · 0⤊ 3⤋
the easiest way to tell if an alternator is bad is to touch a wrench or a screwdriver to the end oposite of the connector wires while the vehicle is running. if there is no magnetic charge then the alternator is bad.
2007-12-08 12:01:42 · answer #6 · answered by Ramble 3 · 0⤊ 4⤋
Start the car, then disconnect the battery. If it runs the alt. is fine. If it shuts off, then it's bad.
2007-12-08 11:50:19 · answer #7 · answered by ? 3 · 0⤊ 5⤋
While the engine is running unhook the negative cable if engine dies bad alt. if it still runs connect the red to the battery pos. and the black to the neg. cable still disconnected from battery should be no less than 13.
2007-12-08 12:00:33 · answer #8 · answered by mark c 3 · 0⤊ 6⤋