Crankshaft position sensor (345), T8: Connection

Fig 1: Identifying Crankshaft Position Sensor Connector

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Fig 2: Crankshaft Position Sensor Wiring Diagram

Courtesy of SAAB-SCANIA OF AMERICA, INC.

The sensor works like a generator and yields a sinusoidal AC. By measuring the frequency, the control module can determine engine speed. After the 58th rib of the perforated disc, there are 2 empty rib spaces. When rib 1 then passes the sensor, the control module knows that the crankshaft is 117° before top dead centre (BTDC).

Voltage from the crankshaft sensor varies with engine speed. When idling, voltage is 5-10 V (AC) and at 2500 RPM, it is approx. 15-20 V (AC). It is the frequency, not voltage, that is important to the control module. As soon as the control module receives pulses from the crankshaft sensor, it grounds the fuel pump relay. Sensor resistance is 860+/-90 Ohm.