BODY 8J1838 - Caterpillar

Machine ECM
The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the speed sensor circuits of the machine.
Table 1
Machine ECM (MID 299)
DTC Code Description System Response
191-2 Transmission Output Speed Sensor: Data Erratic, Intermittent, or Incorrect The FMI 2 will be activated when the ECM determines that the machine is traveling and the transmission speed sensor signal was greater than 200 rpm transmission speed but is now indicating 0 rpm for 2 seconds. The machine must be traveling in second gear, to activate the CID 191 FMI 2 diagnostic code.
191-11 Transmission Output Speed Sensor: Failure Mode Not Identifiable The FMI 11 will be activated if the ECM determines that the machine is traveling and the transmission speed sensor signal is low (0 to 200 rpm), for 10 seconds.
544-11 Engine Cooling Fan Speed Sensor: Failure Mode Not Identifiable Fan speed accuracy may be compromised. Possible causes for an FMI 2 diagnostic code are:
The signal circuit is shorted to ground.
The sensor is not installed correctly.
The sensor has failed.
The ECM has failed. This situation is unlikely.Possible causes for an FMI 11 diagnostic code are:
The signal circuit is shorted to ground.
The sensor is not installed correctly.
The sensor has failed.
The ECM has failed. This situation is unlikely.
Illustration 1 g06140130
Schematic of the speed sensors
The preceding diagram is a simplified schematic of the connections for the speed sensors. The schematic is electrically correct. However, not all the possible harness connectors are shown. Refer to the latest revision of the applicable electrical schematic to view the entire circuitry of the machine.Diagnostic Trouble Code Procedure
Prior to beginning this procedure, inspect the harness connectors that are involved in this 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. Check the wiring for pinch points or abrasions. Look for and repair areas that indicate wires are exposed. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing a troubleshooting procedure.
Table 2
FMI 2 & FMI 11 Troubleshooting
1. Check The Resistance Of The Case Of The Sensor
A. Turn the key start switch and the disconnect switch (if equipped) to the OFF position.
B. Disconnect the machine harness connector from the sensor.
C. Measure the resistance from the signal contact and from the battery contact to the case of the sensor.
The resistance is greater than 10k ohms. OK - The resistance is greater than 10k ohms.
Proceed to Test Step 2.
NOT OK -The resistance is NOT greater than 10k ohms. The speed sensor has failed.
Repair: Replace the sensor.
Proceed to Test Step 6.
2. Check The Resistance Of The Sensor
A. The machine harness connector remains disconnected.
B. Measure the resistance between the signal contact and the battery contact of the connector of the sensor.
The resistance is approximately 140 ohms. OK - The resistance is approximately 140 ohms. The resistance is correct.
Proceed to Test Step 3.
NOT OK - The resistance is NOT approximately 140 ohms. The