GM/Detroit 6.5L – Engine Management – TIMING CONTROL – CRANKSHAFT POSITION SENSOR

Description

The crankshaft sensor is located in the front cover. The sensor is positioned over the crankshaft sprocket and consists of a Hall-effect device and a magnet (figure 5-38). The crankshaft sprocket has four teeth at 90° intervals. As the sprocket rotates, its teeth pass the sensor.

• When no teeth of the sprocket are in alignment with the sensor, the sensor’s magnetic field passes through the Hall-effect device. This causes the device to turn “ON,” which pulls the sensor signal line low (0 volts).
• As a tooth of the crankshaft sprocket comes into alignment with the sensor, the magnetic field passes through the lower reluctance of the tooth instead of the Hall-effect device. This causes the device to turn “OFF,” allowing the sensor signal line to the PCM to go high (5 volts).

The sensor high/low digital signal is monitored by the PCM to determine crankshaft/engine speed and crankshaft position. If the crank signal is lost while the engine is running, the fuel injection system will shift to a calculated fuel injection mode based on the last fuel injection pulse, and the engine will continue to run.

Crankshaft Position Sensor Circuit Operation
The crankshaft position sensor is a Hall-effect device that receives a 5 volt reference signal from the PCM on CKT 416, which it shares with the boost sensor on turbo models (figure 5-39). The sensor converts its changing magnetic field to digital electrical signal and sends it to the PCM on CKT 643.
The sensor shares a ground with the boost sensor, ECT sensor, and IAT sensor on CKT 452. It also shares a 5-volt reference signal with the EGR control pressure/baro sensor and boost sensor.

DTC 19 — “Crankshaft Position Reference Error”
DTC 19 identifies missing crank pulses. It sets when the PCM detects 8 missing crankshaft position pulses on CKT 643 for every cam pulse received.

DTC 57 — “PCM 5 Volt Shorted”
DTC 57 detects when the the 5 volt reference signal on CKT 416 is less than 1 volt. DTC 57 will result in no engine operation.

 

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