CAP 6F7523 - Caterpillar

Use this procedure to troubleshoot a problem with one or more of the engine speed/timing sensors. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.
Table 1
J1939 Code and Description CDL Code and Description Comments
190-8
Engine Speed Sensor : Abnormal Frequency, Pulse Width, or Period 190-8
Engine Speed Sensor : Abnormal Frequency, Pulse Width, or Period The Electronic Control Module (ECM) can default to the secondary engine speed/timing sensor. The default will occur if a valid signal is not received from the primary engine speed/timing sensor.
The engine will shutdown only if the signals from the primary engine speed/timing sensor and the secondary engine speed/timing sensor are abnormal.
The code is logged.
637-11
Engine Timing Sensor : Other Failure Mode 261-11
Engine Timing Offset Fault The ECM has detected that the crankshaft speed/timing sensor and the camshaft speed/timing sensor are not aligned.
The code is logged.
723-8
Secondary Engine Speed Sensor : Abnormal Frequency, Pulse Width, or Period 342-8
Secondary Engine Speed Sensor : Abnormal Frequency, Pulse Width, or Period If a valid signal is not received from the secondary engine speed/timing sensor, the ECM will default to the primary engine speed/timing sensor.
The engine will shutdown only if the signals from the primary engine speed/timing sensor and the secondary engine speed/timing sensor are abnormal.
The code is logged.
4202-8
Engine Speed Sensor #3 : Abnormal Frequency, Pulse Width, or Period 2710-8
Engine Tertiary Speed Sensor : Abnormal Frequency, Pulse Width, or Period The signal from the tertiary speed/timing sensor is ignored. The engine speed is calculated by using the signal from the primary speed/timing sensor. If the signal from the primary speed/timing sensor is ignored, the engine speed is calculated by using the signal from the secondary speed/timing sensor.
4202-11
Engine Speed Sensor #3 : Other Failure Mode 2710-11
Engine Timing Offset fault The ECM has detected that the crankshaft speed/timing sensor and the camshaft speed/timing sensor are not aligned. The Electronic Control Module (ECM) uses the pattern of the pulses from the speed/timing sensors to determine the position of the crankshaft and camshaft. The ECM measures the time between the pulses that are created by the sensors as the gears rotate to determine rpm.After locating the No. 1 cylinder, the ECM triggers each injector in the correct firing order and at the correct unit injector timing. The actual timing and duration of each injection is based on engine rpm and load.
Table 2
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Connect Cat® Electronic Technician (ET).
B. Determine if a code is active or logged.
Codes
Result: A -8 code is active or logged.
Proceed to Test Step 2.
Result: A -11 code is active or logged.
Proceed to Test Step 6.
2. Check the Engine Speed/Timing Circuit
A. Connect Cat ET.
B. Start the engine and run the engine. The problem may occur when