Hi guys. Excuse the interruption. As soon as you see that 18 and 19 volts, you know the voltage regulator is shorting intermittently. They are extremely difficult to get out without causing damage to the diode block. By the time you're done buying replacement parts you can have $100.00 in it not including the time and tools needed to do the repair. Look around for a rebuilt unit with a good warranty. My friend found one with a one-year warranty for just under $200.00 for his car, and another one with a lifetime warranty for around $150.00.
What you must be aware of though is due to the design of these generators, (they switch the field on and off about 400 times per second), is that field coil acts just like an ignition coil and creates huge voltage spikes. Those spikes take out the internal diodes, voltage regulator, and they can interfere with computer sensor signals and cause hard-to-diagnose running problems. It is real common to go through four to six replacement generators in the life of the vehicle. The way to reduce the number of repeat failures is to replace the perfectly good battery at the same time. As they age, they lose their ability to dampen and absorb those spikes. The old battery will work perfectly fine in a 1986 or older GM vehicle that still had the really good generators.
If your battery is less than two years old you shouldn't have to replace it.
Friday, March 9th, 2012 AT 8:39 AM