816K Landfill Compactor and 815K Soil Compactor Systems Caterpillar

Relay - Test

Usage:

816K LT6

Transmission ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the relay circuits of the machine.

Show/hide table

Table 1
Transmission ECM (MID 81)
DTC	Code Description	System Response
444-3	Starter Motor Relay: Voltage above normal	Starter Motor is disabled.
444-6	Starter Motor Relay: Current above normal	Starter Motor is disabled.
3467-3	Main Power Relay: Voltage above normal	Machine electrical systems are disabled.
3467-5	Main Power Relay: Current below normal	Machine electrical systems are disabled.
3467-6	Main Power Relay: Current above normal	Machine electrical systems are disabled.
3470-3	Machine Power Distribution Relay: Voltage above normal	Machine electrical systems are disabled.
3470-5	Machine Power Distribution Relay: Current below normal	Machine electrical systems are disabled.
3470-6	Machine Power Distribution Relay: Current above normal	Machine electrical systems are disabled.

Possible causes for an FMI 3 diagnostic code are:

The relay has failed.
The energize circuit of the relay is shorted to the +battery circuit.
The indicator lamp has failed.
The ECM has failed. ECM failure is unlikely.

Possible causes for an FMI 5 diagnostic code are:

The relay has failed.
There is an open in the circuit.
The ECM has failed. ECM failure is unlikely.

Possible causes for an FMI 6 diagnostic code are:

The energizer circuit of the relay is shorted to ground.
The relay has failed.
The ECM has failed. ECM failure is unlikely.

Show/hide table




Illustration 1	g03827096
Schematic of the Relays

Note: The diagram above is a simplified schematic of the Transmission ECM and the Relay 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.

Show/hide table

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 3. FMI 6 diagnostic code, proceed to Test Step 5.
Begin Process For FMI 3 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 ECM. D. Measure resistance of relay signal contact to all J1 and J2 connectors.	Each reading is greater than 5K Ω.	OK - All resistance measurements are greater than 5K Ω. Proceed to Test Step 7. 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 connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. Proceed to Test Step 7.
Begin Process For FMI 5 Troubleshooting HERE
3. Check The Relay A. Turn the key start switch and the disconnect switch OFF. B. Remove the relay. C. Place a jumper wire between the signal contact and the return contact of the relay. D. Turn the key start switch and the disconnect switch ON. Do not start the engine. E. As the jumper is removed and connected to the contacts, observe any code change.	The code changes to FMI 6 after the jumper wire is installed.	OK - The circuit is correct. The relay has failed. Repair: Replace the relay. Proceed to Test Step 7. NOT OK - The diagnostic code remains active. Proceed to Test Step 4.
4. Check The Machine Harness For An Open A. Turn the key start switch and the disconnect switch OFF. B. Disconnect the harness connectors from the ECM. C. The jumper wire remains installed. D. At the machine harness connector for the ECM, measure the resistance at the ECM contacts for the relay.	Each reading is less than 5 Ω .	OK - The reading is less than 5 Ω, the harness is correct. Proceed to Test Step 7. NOT OK - The reading is greater than 5 KΩ . Circuit open in machine harness. Repair: The open is in the wire for the relay signal or the return wire for the relay. Repair or replace the machine harness. Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. Proceed to Test Step 7.
Begin Process For FMI 6 Troubleshooting HERE
5. Check The Indicator Lamp A. Key start switch and disconnect switch OFF. B. Disconnect the relay from the wiring harness. C. Review the electrical schematic (above) to identify the input and output wires from the coil of the relay. D. Use a multimeter to measure the resistance across the coil of the relay.	The resistance of the coil is less than 50 Ω.	OK - The resistance is less than 50 Ω. Proceed to Test Step 6. NOT OK - The resistance is greater than 5K Ω. The relay has failed Repair: Replace the relay. Note: After the relay is replaced, confirm diagnostic code is no longer active. Note: A resistance that is greater than 50 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. Proceed to Test Step 7.
6. Check The Relay Resistance A. Machine harness remains disconnected from relay. B. Turn key start switch and disconnect switch OFF. C. Disconnect harness connectors from the ECM (or switch panel). D. At harness connector for ECM, measure resistance between lamp relay contact and all ground contacts.	Each reading greater than 5K Ω.	OK - All machine harness readings are correct. Proceed to Test Step 7. NOT OK - A short circuit exists in the machine harness. Repair: The short is between the lamp contact for the relay 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 connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. Proceed to Test Step 7.
7. Check If The Diagnostic Code Remains A. Inspect the harness connectors and clean the contacts of the harness connectors. B. Reconnect all harness connectors. C. Turn key switch and disconnect switch ON. D. Operate the machine. E. Check if diagnostic code is active.	Diagnostic code is no longer present.	OK - Diagnostic code does not exist at this time. Initial diagnostic code may have been caused by poor electrical connection or short at one of the harness connections. Resume machine operation. STOP NOT OK - Diagnostic trouble code has not been corrected. If the diagnostic code has not been corrected after performing the procedure a second time, the ECM may require replacement. Prior to replacing this component, always contact the Technical Communication at your dealership for possible consultation with Caterpillar. This consultation may greatly effect repair time. Follow the steps in Troubleshooting, "Electronic Control Module (ECM) - Replace" if the ECM needs to be replaced. STOP