check current not voltage - but if you're measuring a full 12 V in line, [not from post to post or positive to ground] you've got a dead short someplace and should show a high current flow - a test light will light brightly in that case

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics