865845T01 Mercruiser ECM, Engine Control Module

Illustration 1 g01176182
Schematic
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P1 ECM connector (P1-41) Throttle input #1 (P1-59) Throttle input #2Test Step 1. Inspect Electrical Connectors and Wiring
Remove the electrical power from the ECM.
Thoroughly inspect the J1/P1 ECM connector. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector and the sensor connectors that are associated with the active diagnostic code.
Check the ECM connector (allen head screw) for the proper torque. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
Check the harness and wiring for corrosion, for abrasion, and for pinch points from the throttle switch to the ECM.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of pinch points.Results:
OK - The harness and wiring are OK. Proceed to Test Step 2.
Not OK - There is a problem in the connectors and/or wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.STOPTest Step 2. Check the Status of the Throttle Inputs
Connect the Caterpillar Electronic Technician (ET) to the service tool connector.
Restore the electrical power to the ECM.
Observe the status of the throttle inputs on Cat ET while you operate the throttle switch in each position.
Table 1
Throttle Input    Switch 1    Switch 2    
Low     Off     Off    
Intermediate     Off     On    
High     On     On    Expected Result:The status of the throttle switch corresponds with the table above.Results:
OK - The throttle switch is functioning properly at this time.Repair: Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.STOP
Not OK - One or more of the inputs is incorrect. Proceed to Test Step 3.Test Step 3. Check the Harness between the Throttle Switch and the ECM
Remove the electrical power from the ECM.
Disconnect the wires for the suspect throttle input(s) from the throttle switch.
Restore the electrical power to the ECM.
Check the status of the suspect throttle inputs(s) on Cat ET. Refer to Table 1.
Use a jumper wire to short the wire for the suspect throttle input(s) to engine ground.
Monitor the status of the suspect throttle input(s) on Cat ET.
Remove the jumper wire. Reconnect all wires to the original configuration.Expected Result:The status of the suspect throttle input(s) change when the jumper wire is connected.Results:
OK - The harness and the ECM are OK.Repair: Replace the throttle switch.Verify that the repair eliminates the problem.STOP
Not OK - The status of the suspect throttle input(s) do not change when the jumper wire is installed. Verify that the wire to chassis ground is not open and that the wire has a good connection to chassis ground. Proceed to Test Step 4.Test Step 4. Check the Operation of the ECM
Remove the electrical power from the ECM.
Remove the wires for the suspect throttle input(s) from ECM connector P1.
Install a 208-0059 Adapter Cable As (70-PIN BREAKOUT) at the J1/P1 ECM connector.
Restore the electrical power to the ECM.
Check the status of the suspect throttle input(s) on Cat ET.
Use a jumper wire to short the terminal(s) for the suspect throttle input(s) between the breakout T and engine ground.
Monitor the status of the suspect throttle input(s) on Cat ET.
Remove the jumper wire and breakout T. Reconnect all wires and connectors to the original configuration.Expected Result:The status of the suspect throttle input changes when the jumper wire is connected.Results:
OK - There is either an open circuit or a short circuit in the wiring between the ECM and the throttle switch.Repair: Repair the circuit.Verify that the repair eliminates the problem.STOP
Not OK - The ECM is not responding to the switch inputs.Repair: Verify your results. Refer to electronic Troubleshooting, "Replacing the ECM" before you replace the ECM.STOP