DIODE AS-SUPPRESSOR 1068848 - Caterpillar

Diagnostic Trouble Codes
Table 1
Transmission ECM
DTC Description System Response
444-3 Starter Motor Relay : Voltage Above Normal Unable to crank the engine of the machine.
444-5 Starter Motor Relay : Current Below Normal Unable to crank the engine of the machine.
444-6 Start Motor Relay : Current Above Normal Unable to crank the engine of the machine. Possible Causes and Schematics
Possible causes for an FMI 3 Diagnostic Code are:
The power circuit of the replay is shorted to a higher voltage source.
The relay has failed.
The Transmission ECM has failed. This situation is unlikely.Possible causes for an FMI 5 Diagnostic Code are:
The energize circuit of the relay is open.
The return circuit of the relay is open.
The relay has failed.
The Transmission ECM has failed. This situation is unlikely.Possible causes for an FMI 6 Diagnostic Code are:
A short to ground exists.
The relay has failed.
The Transmission ECM has failed. This situation is unlikely.
Illustration 1 g06271962
Transmission ECM J2 Relay Connections
Note: The diagram above is a simplified schematic of the Transmission ECM connections. The schematic is electrically correct. However, not all the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic for the complete schematic.Troubleshooting Procedure
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.
Table 2
Troubleshooting Test Steps Values Results
1. Identify Active FMI Code Associated With Relay Circuit
Code present. FMI 3 diagnostic code, proceed to Test Step 2.
FMI 5 diagnostic code, proceed to Test Step 4.
FMI 6 diagnostic code, proceed to Test Step 2.
Begin Process For FMI 3 and FMI 6 Troubleshooting HERE
2. Check The Machine Harness For A Short
A. Turn key start switch and disconnect switch OFF.
B. Disconnect harness connection at relay.
C. Disconnect J1 and J2 connectors from the Machine ECM.
D. Measure resistance of relay signal contact to all J1 and J2 connectors.
Each reading greater than 5K Ω. OK - All resistance measurements are greater than 5K Ω.
Proceed to Test Step 3.
NOT OK - One or more readings are less than 5 Ω.
Repair - A short exists between the signal contact and the circuit with the low resistance. Repair or replace the machine harness.
Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose or corroded connection in the circuit. A resistance measurement greater than 5K Ω indicates an open in the circuit.
STOP
3. Check The Relay
A. Connect all harness connections.
B. Turn key start switch and disconnect switch ON.
C. Disconnect the relay from the machine harness.
D. Observe the status of the diagnostic code.
The diagnostic code changes to an FMI 5. OK - The diagnostic code changes to an FMI 5. The relay has failed.
Repair: The relay has failed. Replace the relay.
STOP
NOT OK - The diagnostic code remains.
Proceed to Test Step 6.
Begin Process For