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| Illustration 1 | g01260467 |
Schematic of the Transmission Output Speed Sensor | |
This diagnostic code is associated with the transmission output speed sensor. This diagnostic code is recorded when the ECM determines that the signal is erratic, intermittent, or incorrect.
The possible causes of this diagnostic code are listed:
- Wire (E901-GN) is shorted to the ground circuit while the machine is in operation.
- Wire (E901-GN) is shorted to the +battery.
- An open circuit exists.
- The ECM may have failed. The failure of an ECM is unlikely.
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 0191 FMI 02 is active before performing this procedure.
Note: Use a digital multimeter for the measurements in this procedure.
| Type | Low Range | High Range |
| Sensor 1 | 75 ohms at −40 °C (−40 °F) |
230 ohms at 120 °C (248 °F) |
| Sensor 2 | 600 ohms at −40 °C (−40 °F) |
1800 ohms at 120 °C (248 °F) |
Note: There are two types of speed sensors that can be used in this application. The following test steps state the values that are for the second speed sensor. Determine the speed sensor on the machine. Make sure that the sensor has failed before replacing the sensor.
Note: 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.
System Response:
The machine response is listed:
- The transmission will only operate in first gear.
- Machine functions will be limited.
Note: Before performing the following Test Steps, check to see that the speed sensor is securely mounted. If the mount of the speed sensor is correct and the CID 0191 FMI 02 code is active, then proceed to Test Step 1.
Test Step 1. INSPECT THE HARNESS CONNECTIONS.
- Turn the disconnect switch to the OFF position.
- Inspect all harness connections that are related to the sensor. Make sure that the connectors are clean and tight.
- Check the connectors for proper mating. Ensure that all the seals are present and in place.
- Check the harness for signs of damage or abrasion.
- Check the wires at the connector. Ensure that the wires are secured tightly into the connector.
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit. Take care not to pull the wire out of the connector.
- Check the exposed wires at the connectors for nicks or signs of abrasion.
- Check for moisture inside the connector.
- Check the connectors for dirty contacts or corroded contacts.
- Check each pin and each socket of the machine harness connectors. Ensure that the contacts are properly installed. The contacts should mate correctly when the two pieces of the connector are placed together.
Expected Result:
The machine harness connectors are tight and free of corrosion.
Results:
- OK - The machine harness connectors are tight and free of corrosion. Proceed to test step 2.
- NOT OK - The machine harness connectors are in need of repair.
Repair: Repair the machine harness or replace the machine harness.
STOP
Test Step 2. CHECK THE CIRCUIT FOR AN OPEN.
- Turn the disconnect switch and the key start switch to the OFF position.
- Disconnect the machine harness from the sensor.
- At the machine harness connector for the sensor, install a jumper wire between contact 1 and contact 2 of the harness.
- Disconnect the machine harness connector J1 from the ECM.
- At the J1 machine harness connectors for the ECM, measure the resistance from contact J1-2 for the sensor to J1-3.
Expected Result:
There should be less than 5.0 ohms resistance.
Results:
- YES - The machine harness is correct. Proceed to Test Step 3.
- NO - There is an open circuit in the machine harness. The open circuit is in the wire (E900-WH) or in the wire (E901-GN) of the machine harness.
Repair: Repair the machine harness or replace the machine harness.
STOP
Test Step 3. CHECK THE SENSOR FOR AN OPEN.
- The disconnect switch and the key start switch remain in the OFF position.
- Remove the jumper wire that was used in the previous Test Step.
- Remove the sensor from the machine harness. Insert a multimeter probe in contact 1 and contact 2 of the sensor.
- Measure the resistance of the sensor.
Expected Result:
The resistance should be between 600 and 1800 ohms.
Results:
- YES - The resistance is between 600 and 1800 ohms. The sensor is correct. Proceed to Test Step 4.
- NO - The resistance is not between 600 and 1800 ohms. The sensor has failed.
Repair: Replace the sensor.
STOP
Test Step 4. CHECK IF THE DIAGNOSTIC TROUBLE CODE IS STILL ACTIVE.
- Inspect the harness connectors. Clean the contacts of the harness connectors. Check the wires for damage to the insulation that is caused by excessive heat, battery acid, 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 in order to make sure that the connectors are fully seated. Also, make sure that the clips for each connector are fastened.
- Turn the disconnect switch and the key start switch to the ON position.
- Operate the machine.
- Determine if the CID 191 FMI 02 is active.
Expected Result:
The CID 191 FMI 02 is active.
Results:
- YES - The CID 191 FMI 02 is active. The diagnostic trouble code has not been corrected.
Repair: Check the circuit again. The failure of an ECM is unlikely. Exit this procedure and perform this procedure again. If the cause of the diagnostic trouble code is not found, replace the ECM. Prior to replacing an ECM, always contact your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
STOP
- NO - The CID 191 FMI 02 is not active. The diagnostic trouble code does not exist at this time. The initial diagnostic trouble code was probably caused by a poor electrical connection. Resume normal machine operation.STOP