Crankshaft Position Sensor

The TDC sensor is mounted so that it is triggered by a 3 toothed wheel attached to the crankshaft pulley. Figure . This gives an 8 degree ATDC reference for each cylinder on the "A" bank. The correct TDC sensor air gap is 0.018-1.042 in. (0.46-1.07 mm). The TDC sensor can be checked using an oscilloscope. Connect the oscilloscope positive lead to the Engine Control Unit (ECU) terminal No. 1 or the TDC sensor Blue lead. Connect the Oscilloscope negative lead to the ECU terminal No. 2 or the sensor screen. Observe oscilloscope for a normal TDC sensor pattern. See Figure .