5090 Mercruiser BREAKER ASSEMBLY

Table 1
Diagnostic Codes Table    
Code and Description    Conditions which Generate this Code    System Response    
677-5 Engine Starter Motor Relay : Current Below Normal     The Electronic Control Module (ECM) detects an open in the circuit for the start control relay for more than 5 seconds.
The output driver must be off in order for this code to become active.     The code is logged.
The amber warning lamp is illuminated.    
677-6 Engine Starter Motor Relay : Current Above Normal     The ECM detects a short in the circuit for the start control relay for more than 5 seconds.
The output driver must be on in order for this code to become active.     The code is logged.
The amber warning lamp is illuminated.    The engine ECM contains the logic and the outputs for starting the engine. The logic for starting the engine is customer programmable. The logic responds to inputs from the following components: engine control switch, emergency stop switch, remote start switch, data link and other inputs.The ECM also has outputs that are used for communicating the current state of engine operation. One of the outputs sends a signal to indicate that the crank terminate speed has been achieved. Another output sends a signal that indicates that the engine is running. Both of these outputs are low side ECM drivers. The power for the circuits is provided at the electrical component and the ground circuit is provided by the ECM. Refer to Troubleshooting, "Indicator Lamp - Test" for information that is related to troubleshooting these circuits.The most likely causes of any of these diagnostic codes are a poor electrical connection or a problem in a wiring harness. The next likely cause is a problem with one of the solenoids that are related to the code. The least likely cause is a problem with the ECM.The ECM supplies +Battery voltage to the start control relay when the logic determines the necessity. The ECM removes the voltage when the crank terminate speed has been achieved. Also, if the timer for the "Cycle Crank Time" parameter is exceeded, voltage will be removed from the start control relay.
Illustration 1 g02025907
Schematic for the components of the engine starting system
Illustration 2 g02029068
Location of the components for the engine starting system (right side engine view) (1) J2/P2 ECM connectors (2) Electric start control (start control relay)
Illustration 3 g01413257
Location of the connector for the air start control (right rear engine view) (3) Harness connector for the air start control (start control relay)
Illustration 4 g02029132
Terminal locations at the P2 ECM connector that are associated with the starting system (P2-17) Starting motor output (P2-19) Return
Illustration 5 g01155187
Terminal locations at the harness connector for the start control relay (1) Start control relay (2) Return
Table 2
Troubleshooting Test Steps    Values    Results    
1. Inspect the Electrical Connectors and the Wiring
A. Set the engine control switch to the OFF position. Remove the electrical power from the engine.
B. Thoroughly inspect ECM connectors (1) . Also, thoroughly inspect the other components for the starter circuit that is for your application. Refer to Testing and Adjusting, "Electrical Connectors - Inspect" for details.
C. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the engine starting system.
D. Check the fastener for each of the ECM connectors for the proper torque. Refer to Testing and Adjusting, "Electrical Connectors - Inspect" for the correct torque values.
E. Check the wiring harnesses for abrasion, for corrosion and for pinch points.
   
Damaged Connector or wiring    
Result: The harness and wiring appear to be OK.
Proceed to Test Step 2.
Result: There is a problem in the wiring harness.
Repair the connectors and/or the wiring. Replace parts, if necessary. Ensure that all of the seals are properly in place and ensure that the connectors are coupled. Verify that the problem is resolved.
   
2. Check for Active Diagnostic Codes
A. Turn the engine control switch to the OFF position. Remove the electrical power from the engine.
B. Connect Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
C. Restore the electrical power to the engine. Turn the engine control to the STOP position.
Note: The 677-5 Engine Starter Motor Relay : Current Below Normal can only be detected when the output for the start command is off. The output is normally off when the engine control switch is in the STOP position. The output is also off when the output for the crank terminate relay is activated.
D. Turn the engine control to the START position. Attempt to start the engine.
Note: The 677-6Engine Starter Motor Relay : Current Above Normal can only be detected when the output for the start command is on. The output is normally on when the engine control is switched from the STOP position to the START position. The output remains on during engine cranking.
E. Turn the engine control to the STOP position.
   
Active Diagnostic codes    
Result: No diagnostic codes were activated.
The output for the starting system appears to be OK. The initial diagnostic code was probably caused by a poor electrical connection. If an intermittent electrical problem is suspected, refer to Testing and Adjusting, "Electrical Connectors - Inspect", for information that is related to troubleshooting intermittent electrical problems.
Result: A 677-5 diagnostic code was activated during the test.
This code can be caused by an actual open circuit or by a short circuit to the +Battery side.
Proceed to Test Step 3.
Result: After the engine was cranked, a 677-6 diagnostic code was activated.
There is a short circuit in the harness or in the solenoid.
Proceed to Test Step 7.