SEAT ASSEMBLY 9K8342 - Caterpillar

Diagnostic Codes
Table 1
Machine ECM (MID 39)
DTC Code Description System Response
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.
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 and Schematics
Possible Causes for a DTC 585-8 and DTC 673-8 are:
There is debris in the sensor.
A resistor has failed.
The energize wire is shorted to the ground circuit while the machine is in operation.
The energize wire is shorted to +battery.
An open circuit exists.
The sensor has failed.
The ECM has failed. This condition is unlikely.There are two speed sensors for transmission output speed listed below:
The transmission output speed (TOS) sensor 1 (leading).
The transmission output speed (TOS) sensor 2 (trailing).The Machine ECM determines the existence of this diagnostic code by comparing the signals from sensor 1 to the signals from sensor 2. This diagnostic code is recorded when one sensor shows a valid speed signal above the minimum and the other is below the dropout signal level.Note: Failures of the transmission output speed sensor will be shown only while the machine is moving. One of the following conditions must be present before the diagnostic code will be active:
The signal from TOS Sensor 2 (trailing) to the ECM is incorrect.
Illustration 1 g03241717
Machine ECM J1 Speed Sensors
Note: The diagram above is simplified schematic of the Machine ECM connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision Electrical Schematic, UENR0383 for complete information.Troubleshooting 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 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 for Machine Movement
A. Perform normal operations to move the machine.
The machine moves.