That's typical of a dead battery or bad cable connections. Start by measuring the battery's voltage right on the posts. You will find 12.6 volts if it's good and fully charged. If you find around 12.2 volts, it's good but discharged. If it's around 11 volts or less, it has a shorted cell and must be replaced.
If it's just dead, charge it at a slow rate for an hour, then try to crank the engine. If the engine starts, measure the battery voltage again while the engine is running. It must be between 13.75 and 14.75 volts. If it stays near 12.6 volts, have the charging system tested by your mechanic.
If the battery voltage is close to 12.6 volts but you still get that chattering when trying to crank the engine, have a helper do the cranking while you take the voltage reading again. If the voltage stays above about 10.0 volts during cranking, move the voltmeter probes from the battery posts to the cable clamps. (You're moving each probe about 1/2"). Take the reading again. It should be the same as in the last test. If the voltage is substantially lower, one of those cables is loose or has corrosion between it and the battery's post. You can figure out which one by moving just one meter probe from the battery post to its cable clamp at a time.
If this appears to be the cause of the problem, a more accurate way of finding the bad connection is to place one meter probe on the battery's positive post, and the other probe on the positive cable clamp. You SHOULD find 0.0 volts because those are both the same point in the circuit, but if that connection is loose or dirty, current flowing through it will cause some voltage to be dropped. That is what you're measuring in this test. Have your helper crank the engine just long enough to get the reading. You're allowed up to 0.2 volts during cranking. If the connection is causing the problem, it will be obvious because the voltage will be real high, as in a few volts.
If you find a real low voltage, do the same test with both meter probes on the negative post and cable clamp.
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Monday, December 28th, 2015 AT 3:37 PM
