ADAPTER 5P3588 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with one or more of the engine speed/timing sensors. Also, use this procedure if one of the following codes is active or easily repeated.
Table 1
J1939 Code and Description Comments
190-8
Engine Speed : Abnormal Frequency, Pulse Width, or Period Code is for the crankshaft sensor.
The ECM has lost the crankshaft sensor signal.
The engine is shutdown.
The code is logged.
637-11
Engine Timing Sensor : Other Failure Mode The engine has failed the automatic timing calibration during engine start-up.
The code is logged.
The value of the timing offset that has been stored in memory will be used. This value will continue to be used for the timing calibration until the diagnostic is resolved.
723-8
Engine Speed Sensor #2 : Abnormal Frequency, Pulse Width, or Period Code is for the camshaft sensor.
The engine is shutdown.
The code is logged. This engine utilizes two speed/timing sensors to detect the speed and the timing for the engine. The primary (camshaft) speed/timing sensor is used to detect engine speed and camshaft position during engine starting and also while the engine is running. The secondary (crankshaft) speed timing sensor is used only during engine cranking in order to determine top center of the No. 1 cylinder. Use this procedure to troubleshoot electrical problems with the circuit for the primary (camshaft) engine speed/timing sensor. For information related to troubleshooting the secondary engine speed/timing sensor, refer to Troubleshooting, "Speed/Timing (Secondary) - Test".
Illustration 1 g02644586
Features machined into the cam gear for speed/timing detection
The primary speed timing sensor utilizes a series of holes that are machined into the face of the cam gear to establish a signal. The pattern of holes includes two holes that are strategically spaced in order to provide a unique signal pattern to the ECM. The ECM utilizes the signal pattern to locate top center for the No. 1 cylinder, initiate ignition for the cylinders, and for engine speed determination.
Illustration 2 g02644459
Features machined into the flywheel for speed/timing detection
Similarly, the secondary speed timing sensor utilizes a series of holes that are machined into the outer surface of the flywheel to establish a signal. The pattern of holes includes two holes that are strategically spaced in order to provide a unique signal pattern to the ECM. The ECM utilizes the signal pattern to locate top center for the No. 1 cylinder.If the ECM detects a problem with the primary speed/timing sensor signal, the engine will not start and the engine will not run. If the ECM loses the signal from the secondary speed/timing sensor with the engine stopped, the engine will not be able to start. If a problem with the signal from the secondary speed/timing sensor occurs while the engine is running, the engine will continue to run.A timing offset is determined during each engine start-up. The value of the timing offset is stored in the non-volatile memory of the ECM until the successful completion of the next engine start-up. If a failure mode for the crankshaft speed/timing sensor is detected during