SEAL-AIR 3843543 - Caterpillar

Table 1
Diagnostic Trouble Codes for the Start Relay
J1939 Code CDL Code Code Description
(code descriptions may vary) Comments
677-5 444-5 Starter Motor Relay : Current Below Normal The Electronic Control Module (ECM) detects a low current condition (open circuit) in the start relay control circuit.
677-6 444-6 Starter Motor Relay : Current Above Normal The Electronic Control Module (ECM) detects a high current condition (short circuit) in the start relay control circuit.
Follow the troubleshooting procedure in order to identify the root cause of the fault. During the following procedure, refer to the electrical schematic for the application.Complete the procedure in the order in which the steps are listed.
Table 2
Troubleshooting Test Steps Values Results
1. Inspect Electrical Connectors and Wiring
A. Check that the fuses are not blown.
B. Inspect the terminals on the start relay. Refer to Troubleshooting, "Electrical Connector - Inspect" for details.
C. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the start relay.
D. Check the screw for the ECM connector for the correct torque of 6 N m (53 lb in).
E. Check the harness for abrasion and pinch points from the start relay back to the ECM.
Loose connection or damaged wire
Result: There is a fault in a connector or the wiring.
Repair: Repair any faulty connectors or replace the wiring harness. Ensure that all of the seals are properly in place and ensure that the connectors are correctly coupled.
Replace any blown fuses.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
Result: All connectors, pins, and sockets are correctly coupled and/or inserted. The harness is free of corrosion, abrasion, and pinch points. The fuses are not blown.
Proceed to Test Step 2.
2. Check for Active Diagnostic Codes
A. Connect the electronic service tool to the diagnostic connector.
B. Turn the keyswitch to the ON position.
Note: Do not start the engine.
C. Use the electronic service tool to check for active diagnostic codes.
Diagnostic codes
Result: Diagnostic code 677-5 or 444-5 is active or recently logged.
Proceed to Test Step 3.
Result: Diagnostic code 677-6 or 444-6 is active or recently logged.
Proceed to Test Step 6.
3. Check the Battery Supply Voltage at the Relay Connector
A. Turn the keyswitch to the OFF position.
B. Turn the keyswitch to the ON position. Do not start the engine.
C. Measure the voltage between the battery input terminal on the relay and a suitable ground.
At least 11 VDC for a 12 VDC system. At least 22 VDC for a 24 VDC system.
Result: The voltage is not within the expected range.
Repair: Repair or replace the battery supply wiring to the start relay.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
Result: The voltage is within the expected range.
Proceed to Test Step 4.
4. Create a Short Circuit at the Relay Connector
A. Turn the keyswitch to the OFF position.
B. Remove the start relay.
C. Fabricate a jumper wire. Install the jumper wire between terminal 1 and terminal 2 on the harness connector