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Re: Battery/Alternator Problems Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Sun, 25 May 2008 14:27:48
In Reply to: Battery/Alternator Problems, Colby, Sun, 25 May 2008 10:13:02 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Let's start with the silly questions - Do you know the new alternator is working and/or hooked up properly?
Question 1 - with a charged battery - turn the key to ON, but don't start the car. Do you see the battery light? If yes, go on. If not, problem 1. That light is necessary for the alternator to work. Power goes from the battery, through the ignition switch, through the light, and through a thin green or yellow wire to the D+ terminal on the alternator. And the alternator chassis is grounded. If any of that path is broken, the alternator will never produce voltage. This might have been why the first alternator seemed bad. As a simple step, remove the thin green (or yellow) wire from the lug on the back of the alternator, and touch it to ground while the key is ON. If the bat light comes on, that part of the circuit is good. If it isn't, fix it. Note: if the bulb has died (rare, but happens), check the manual for the proper bulb. It's a special size necessary for the alternator to work.
If the wiring seems OK, start the car. Turn off all electrical loads, like the cabin fan, lights, AC. Take a voltmeter, set to Volts, and touch the negative lead to a good ground source, like the chassis. NOT THE BATTERY. Now, touch the positive lead of the meter to the positive battery terminal. It should read at least 13.0 volts. (13.1, 13.2, etc). If you see 12.6 or less, the alternator isn't charging. If you see at least 13.0 volts, touch the meter lead to the negative battery terminal. It should read 0, plus or minus no more than about 100 millivolts (0.1 volts). Any more, and you've got a bad ground connection.
Next, touch the meter lead to the body of the alternator. It should also read right near 0 volts. If not, the alternator ground is bad.
The trouble with the 900 charging system is that if the alternator ground is bad, not only won't it charge the battery, the battery light won't come on to tell you there's a problem. And the battery light is necessary for the alternator to work. So if the bulb burns out and you don't check that it works, you won't know that your alternator isn't charging the battery. So as a rule, always turn the key to ON for a second or so before starting, and make sure all the bulbs work.
Why did you change the alternator in the first place? Did you check the voltage on it? And can you be sure the new alternator is working properly? Always check the voltages. The battery needs more than 12.6 volts in order to charge - typical voltages when the car is running are in the low 13 to low 14 volt range.
posted by 76.202.162...
, Sun, 25 May 2008 14:27:48 <-- Viewing This Message
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