HARNESS AS 4P0498 - Caterpillar

Transmission ECM
The following is a list of diagnostic codes that are associated with the Speed Sensors 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
585-8 Transmission Output Speed Sensor #1 : Abnormal Frequency, Pulse Width, or Period Transmission shifting may be harsh
Shift hesitation during directional shifts
669-8 Transmission Input Speed Sensor : Abnormal Frequency, Pulse Width, or Period Transmission shifting may be harsh
Shift hesitation during directional shifts
673-8 Transmission Output Speed Sensor #2 : Abnormal Frequency, Pulse Width, or Period Transmission shifting may be harsh
Shift hesitation during directional shifts Possible Causes for an FMI 8 DTC 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 unlikelyNote: 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. For sensors powered via the fuse panel, check the condition of the appropriate fuse before beginning the troubleshooting procedure.
Illustration 1 g03174296
Transmission ECM J1 Speed Sensors
Note: The diagram above is simplified schematic of the Transmission ECM connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, UENR2441 for the complete schematic.Diagnostic Trouble Code Procedure
Table 2
Troubleshooting Test Steps Values Results
1. Identify Active DTC 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 THE RESISTANCE OF THE SENSOR
A. Turn the key start switch and the disconnect switch to the OFF position
B. Disconnect the machine harness from the speed sensor
C. Measure