UHF Antenna problem

There should be a low resistance if you test the antenna it's self from the earth to coil element in the antenna.
Cheers Peter

With the AE4006, there should be NO continuity between the coax centre and braid with the base, lead and plug assembled properly.
There should be continuity from the braid to the vehicle chassis, and continuity between the centre pin of the plug and the antenna mounting thread. I'm not sure where your spring is with this type of antenna, it's designed to be directly mounted onto the antenna base.
Unless you are using the elevated feed base (spring plus the chrome plated tube) you shouldn't add a spring to a UHF antenna, it will change the tuning enough to be a problem.
Some of the co-linear construction antennas will show up as a DC short circuit across the coaxial cable, this is normal. But the AE4006 and whatever base you have, shouldn't have a short across the coax...