Circuit Description

The engine oil pressure (EOP) switch is a normally closed switch that opens with the proper oil pressure. With the ignition switch turned ON and the engine not running, the powertrain control module (PCM) should detect a low signal voltage input. With the engine running, the pressure switch opens, and the PCM should detect a high signal voltage input. The PCM tests the state of the EOP circuit with the ignition switch turned ON, and the engine turned OFF. If the PCM detects a high voltage input on the EOP signal circuit, DTC P1189 will set.