Auto Service Professional

DEC 2018

Magazine for the auto service professional

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D e c e m b e r 2 018 A SP 19 the dashboard or behind the right kick panel. It can be easily accessed once the trim panels are removed. Mechanical wear or damage to the rack or motor will usually produce chattering noises or rough steering, oen more pronounced when turning one direction. Boost in only one direc- tion also indicates motor or rack problems. How- ever, if these symptoms go away when the motor is disconnected, the rack is probably OK and it's time to look for fault codes. Danny Holland Valley Car care GM CRANKSHAFT POSITION SENSOR (CKP) A P0336 code on an LS-engine-equipped GM vehicle refers to a problem with the CKP (crank- sha position sensor). e CKP is a two-wire sensor (signal and ground). e sensor features a permanent magnet (or three-wire hall-effect sensor, featuring ground, voltage and signal) mounted in the right rear side of the engine block that aligns with a toothed reluctor wheel that is attached to the cranksha. As the crank rotates, the reluctor wheel passes by the magnet, generat- ing an AC signal that the ECU uses to identify engine speed. Depending on the engine design and model, the number of reluctor wheel teeth may vary. In the early LS engines, a 24-tooth reluctor wheel was used, followed by the use of a 58-tooth wheel in later versions. Keep in mind that even within the same en- gine family (the GM LS engines are an example), the tooth count will vary, and the tooth count must be matched to the programming in the ECU. In combination with the camsha position sensor (CMP), the CKP signals are used by the ECU to manage fuel injection and spark delivery. A crankshaft-mounted reluctor wheel features a series of teeth that provide a crank position signal to the crankshaft position sensor. Crank position sensors are mounted to the engine block in a location that aligns to the toothed reluctor wheel. When servicing, make sure that the sensor is clean and free of any contaminants.

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