CORE A. 3S5074 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the primary engine speed/timing sensor. Also use this procedure if a problem is suspected with the secondary engine speed/timing sensor. Use this procedure to troubleshoot the electrical system if a diagnostic code in Table 1 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 code is logged against the primary speed sensor (crank/speed timing A). 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 shut down only if the signals from the primary engine speed/timing sensor and the secondary engine speed/timing sensor are abnormal.
723-8
Engine Speed Sensor #2 : Abnormal Frequency, Pulse Width, or Period 342-8
Secondary Engine Speed Sensor : Abnormal Frequency, Pulse Width, or Period The code is logged against the secondary speed sensor (camshaft/speed timing B). 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 shut down only if the signals from the primary engine speed/timing sensor and the secondary engine speed/timing sensor are abnormal. Refer to the main engine schematic for pinout locations of the speed/timing sensors.
Table 2
Troubleshooting Test Steps Values Results
1. Check the Engine Speed/Timing Circuit
A. Connect Cat® Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
B. Turn the keyswitch to ON.
C. Start the engine and run the engine.
Note: The problem may occur when the engine is at any operating temperature. However, the problem is more likely to occur when the engine is at the normal operating temperature.
Speed/Timing Circuit
Result: The engine started.
Proceed to Test Step 2.
Result: The engine did not start.
Proceed to Test Step 3.
2. Check for Codes
A. While the engine is running, monitor Cat ET for diagnostic codes. Also monitor the "Engine Starting" screen for an engine speed/timing that is "Not Detected".
B. Wait at least 30 seconds for activation of the diagnostic codes. Look for these codes on Cat ET:
• 190-8
• 342-8
• 723-8
Codes
Result: There is an active diagnostic code or there is a timing pattern that is "Not Detected".
Proceed to Test Step 5.
Result: There is not an active diagnostic code and there is not a timing pattern that is "Not Detected".
Repair: Download the "Product Status Report" from the engine ECM. Troubleshoot any diagnostic codes that may be present.
Return the unit to service.
3. Check the Battery Voltage
A. Monitor the "Engine Starting" screen in Cat ET.
B. Monitor the "Battery Voltage". Crank the engine