alternator or Battery
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You know I tried that, I get a reading of 27.5 volts. I also tried that on my brand new 2008 Dodge ram and I also get the same reading, how come. I know that my new vehicle is not faulty. I am going to buy a new multi tester tomorrow, i may be getting a wrong reading. The problem with the Dakota does not occur all the time it is intermittent, so if I could test it when the problem occurs that may help.
nash211
nash211
Last edited by nash211; Mar 10, 2009 at 10:11 PM.
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You know I tried that, I get a reading of 27.5 volts. I also tried that on my brand new 2008 Dodge ram and I also get the same reading, how come. I know that my new vehicle is not faulty. I am going to buy a new multi tester tomorrow, i may be getting a wrong reading. The problem with the Dakota does not occur all the time it is intermittent, so if I could test it when the problem occurs that may help.
nash211
nash211
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Joined: Feb 2009
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From: Chicago
Also, make sure that the alternator is tested for a failed diode. This is an easy test if you have access to a multimeter that can read A/C voltage. Take an A/C reading across both battery terminals with the car running. Anything more than about .05VAC is too much. I've seen cars running over 1 volt of A/C voltage that started just fine, but had all sorts of intermittent drivability problems due to memory getting corrupted.
The bottom line is that modern electronics are EXTREMELY sensitive to voltage fluctuations. Many of the old assumptions about 12v electrical systems no longer hold true. A battery/alternator issue these days will cause problems LONG before the lights get dim when you try and start the car.
The bottom line is that modern electronics are EXTREMELY sensitive to voltage fluctuations. Many of the old assumptions about 12v electrical systems no longer hold true. A battery/alternator issue these days will cause problems LONG before the lights get dim when you try and start the car.
Checking Ripple Voltage Ripple voltage or (AC voltage) can be measured by switching your DMM to AC and connecting the black lead to a good ground and the red lead to the "BAT" terminal on the back of the alternator, (not at the battery). A good alternator should measure less than .5 VAC with the engine running. A higher reading indicates damaged alternator diodes.
Alternator Leakage Current To check alternator diode leakage, connect the multimeter in series with the alternator output terminal when the car is not running. Leakage current should be a couple of milliamps at most; more often, it will be on the order of 0.5 milliamps. Use care when disconnecting the alternator output wire; make sure the battery is disconnected first.