SHAFT AS 1396866 - Caterpillar

Transmission ECM
Table 1
Transmission ECM
DTC Code Description System Response
668-3 Transmission Direction Switch: Voltage Above Normal The shift lever will not shift out of neutral when this diagnostic code is active.
668-4 Transmission Direction Switch: Voltage Below Normal The shift lever will not shift out of neutral when this diagnostic code is active. Possible Causes for an FMI 3 Diagnostic code are:
A wire is shorted to the +battery circuit in the machine harness.
A wire is open.
The ECM has failed. A failure of the ECM is unlikely.Possible Causes for an FMI 4 Diagnostic code are:
Loss of power to the sensor/switch.
The sensor/switch has failed.
The transmission shift lever exceeds the normal operating range.
The signal circuit is shorted to ground.
The ECM has failed. A failure of the ECM is unlikely.The logic table displays the outputs for the positions of the transmission shift handle:
Table 2
Logic table for the transmission switches
Selected Gear Active Functions (Outputs)
FWD - 1 FWD, 1ST
FWD - 2 FWD, 2ND
FWD - 3 FWD, 3RD
FWD - 4 FWD. 4TH
NEUTRAL (ALL) NEUTRAL, RUN
RVS - 1 RVS, 1ST
RVS - 2 RVS, 2ND
RVS - 3 RVS, 3RD
RVS - 4 RVS, 4TH 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. 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 3
Troubleshooting Test Steps Values Results
1. Identify Active FMI Code Associated With Sensor Circuit
Code present. FMI 3 diagnostic code, proceed to Test Step 2.
FMI 4 diagnostic code, proceed to Test Step 4.
Begin Process For FMI 3 Troubleshooting HERE
2. Check The Circuit For A Short
A. Turn the keyswitch OFF.
B. Disconnect the switch from the machine harness.
C. Disconnect the J1 and J2 machine harness connections from the Machine ECM.
C. At the machine harness connector for the ECM, one at a time, measure the resistance between each of the signal contacts to every other contact used in the J1 and J2 machine harness connectors.
The resistance is greater than 5K Ω. OK - The resistance is correct.
Proceed to Test Step 3.
NOT OK - The check of the resistance is not correct.
Repair: There is a short in the signal circuit of the machine harness. Repair or replace the machine harness.
Note: A resistance greater than 5 Ω but less than 5K Ω indicates a loose or corroded circuit connection. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit.
STOP
3. Check the Operation of the Switch
A. The keyswitch remains OFF.
B. Reconnect all harness connectors.
C. Use Cat® Electronic Technician (Cat ET) to monitor the transmission.
D. Active all possible gear switch combinations and observe the enabled functions on Cat ET.
E. Refer to the table 2 to identify any faults in the transmission engagement.
The gear