Join Date: Jan 2006
Location: Northern California
Thanked 2,589 Times in 2,087 Posts
You cant test AC voltage using the batteries because they act as a filter skewing the results. You have to test directly off the alternator. Touch the tester red line to the hot post on the back of the alternator and then the black wire to the alternator body. Thats the most accurate.
Then I advise turning on all your electronic accessories and have a friend sit in the cab ramping the throttle up to 2000 RPM. Test the AC voltage again and it will be higher...
Also, yes it sounds like your CPS is bad or faulty (or the connection) and that can cause problems like you described.
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