The 2 wire sensors have no connection to the brass body so the sensing wire connects to 1 pin the other pin goes to ground I would not rely on the oil adaptor body for ground as it has a gasket at the bottom & top of the bolt connect directly to the firewall ground. If still no luck place a piece of wire in the 2 holes on the connector if it works then the pins are not contacting the pins in the temp sensor. If it does not work then the crimp on either end of the ground wire could be crimped into the plastic insulation & not the wire