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| Illustration 1 | g01309424 |
Schematic of the Engine Speed Sensor | |
This diagnostic code is associated with the Engine Speed Sensor. The FMI 08 means that the ECM has determined that the data is an Abnormal Frequency, Pulse Width or Period. The engine speed sensor has a signal wire and a ground. The ECM is able to diagnose the signal wire. The signal wire provides a frequency input to the ECM which calculates revolutions per min (RPM). If this diagnostic code is active, the ECM will keep it active until a good sensor signal is observed by the ECM. The engine must be running in order for the ECM to determine if the active code can be cleared.
The possible causes of this diagnostic code are listed below:
- The sensor has failed.
- Intermittent connections or poor connections
- Mechanical devices are loose.
- The ECM has failed. This is unlikely.
Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure and in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.
Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 0190 FMI 08 is active before performing this procedure.
Note: For trouble shooting this diagnostic code, the engine may need to be running. Use a digital multimeter for the measurements in this procedure.
System Response:
A level 2 warning will be generated.
Test Step 1. CHECK FOR A SHORT ON THE SIGNAL CIRCUITS.
- Turn the disconnect switch and the key switch to the OFF position.
- Disconnect the machine harness J1 and J2 connectors from the machine ECM.
- Check the continuity between the signal wire (450-YL) and every other pin on the J1 and J2 connector.
- Check the continuity between the return wire (451-BR) and every other pin on the J1 and J2 connector.
Expected Result:
The resistance measurements are all greater than 5000 ohms.
Results:
- OK - The resistance measurements are all greater than 5000 ohms. Proceed to Test Step 2.
- NOT OK - The resistance on one or more circuits is less than 5000 ohms. There is a short in the circuit with the low resistance measurement.
Repair: The machine harness has failed. Repair the machine harness or replace the machine harness. After the repair, start the engine. Check to see if diagnostic is cleared.
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Test Step 2. CHECK IF THE DIAGNOSTIC CODE REMAINS
- Inspect the harness connectors and clean the contacts of the harness connectors and check the wires for damage to the insulation that is caused by excessive heat, corrosion, or chafing.
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit.
- Reconnect all harness connectors making sure that the connectors are fully seated and the clips for each connector are completely fastened.
- Turn the disconnect switch and the key start switch to the ON position.
- Start the engine.
- Check the status of the CID 0190 FMI 08.
Expected Result:
The CID 0190 FMI 08 is not active.
Results:
- OK - The CID 0190 FMI 08 is not active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor connection or a short at one of the connectors that was disconnected and reconnected. Resume normal operation.STOP
- NOT OK - The CID 0190 FMI 08 is active. The diagnostic code has not been corrected. The speed sensor may have failed.
Repair: If the cause of the problem is not found, contact the Technical Communicator for your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, see Troubleshooting, "Electronic Control Module (ECM) - Replace".
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