Mr. Bojangles

By Field lead you mean the plug or the large wire used for the test? Im reading .025 on the Fluke and the multimeter at the house and it's still doing the unlock/lock again. Charging used to be 14.5v but now it's only putting out 13.77v.

Mike, just need some verification here. 99 Cummins with a power puck as my only electrical mod. vac reading of .035 at idle. When raised to 2000 rpm I see a reading of .055 vac. Measured with a borrowed fluke 17?? meter from work electrician. Is this within spec? I had the unlock/lock issue about 8 months ago, rebuilt alternator (Bosch reman) and get a random unlock/lock about once every couple of months. When it happens, it only does it once or twice, fairly spaced out in my hour long drive to/from work. I usually just clean my posts and terminals and issue won't return for a couple of months. I am currently in the process of building and replacing all of my terminals and battery wires/grounds as I had the driverside negative pop off the other day which made the issue come back. I do have slight corrosion of the positive cables. Thanks!