COLLAR 1608125 - Caterpillar

Transmission ECM
The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the speed sensor circuits of the machine.
Table 1
Transmission ECM (MID 81)
DTC Code Description System Response
190-8 Engine Speed Sensor: Abnormal frequency, pulse width, or period The engine speed and operator indicator may be inconsistent during operation.
585-8 Transmission Output Speed Sensor 1: Abnormal frequency, pulse width, or period Transmission shifting may be harsh. The transmission control may be unable to determine the direction of travel. The transmission control will be unable to determine the ground speed of the machine.
672-8 Torque Converter Output Speed Sensor: Abnormal frequency, pulse width, or period Transmission shifting may be harsh. The transmission control may be unable to determine the direction of travel. The transmission control will be unable to determine the ground speed of the machine.
673-8 Transmission Output Speed Sensor #2: Abnormal frequency, pulse width, or period Transmission shifting may be harsh. The transmission control may be unable to determine the direction of travel. The transmission control will be unable to determine the ground speed of the machine. Possible causes for an FMI 8 diagnostic code are:
The sensor has failed.
The spacing of the sensor is incorrect.
Intermittent connections or poor connections.
Mechanical devices are loose.
Incorrect software is loaded to the ECM.
The ECM has failed. ECM failure is unlikely.
Illustration 1 g03527897
Schematic of the Speed Sensors
Note: The diagram above is a simplified schematic of the Transmission ECM and the Speed Sensor connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision for the complete schematic.Diagnostic Trouble Code Procedure
Note: 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. If a problem with a connection is found, correct the problem and verify that the diagnostic code is active before performing a troubleshooting procedure.
Table 2
Troubleshooting Test Steps Values Results
1. Identify Active FMI Code Associated With Sensor Circuit Code present. FMI 8 diagnostic code, proceed to Test Step 2.
Begin Process For FMI 8 Troubleshooting HERE
2. Check for Machine Movement
A. Perform normal operations to move the machine.
The machine moves. OK - The machine moves.
Proceed to Test Step 3.
NOT OK - The machine does not move.
Repair: Refer to Troubleshooting , UENR0795, " Symptom Procedures - Transmission " for troubleshooting loss of machine movement.
Proceed to Test Step 6.
3. Check The Resistance Of The Sensor
A. The disconnect switch and the key start switch remain in the OFF position.
B. Disconnect the sensor from the machine harness. Insert a multimeter probe in contact 1 and contact 2 of the sensor.
C. Measure the resistance of the sensor.
The resistance is between 800 and 1800 Ω. OK - The resistance is between 800 and 1800 ohms.
Proceed to Test Step 4.
NOT OK - The resistance is not between 800 and 1800 Ω. The speed sensor has failed.
Repair: Replace the speed sensor. Adjust the speed