1967 Dodge Coronet Phantom Voltage

Hi. Here's A Perplexing Problem That Baffles
Me To No End. I Remove Both Battery Terminal
Cables, Positive And Negative, Then Set Meter To
20 Volts D.C.---- Then Touch Negative Cable Which
Is Still Grounded To Motor, Then Touch Negative
Post On Battery....And I Get A 3.67 Volt Reading
On The Meter!! Where Is The Voltage Coming From? Is The Battery Bleeding Current? I Get
The Same Reading With The Positive Cable Connected To Positive Battery Terminal Too.
What's Up With That? Thanks!!