861926T 3 Mercruiser ECM, Engine Control Module

Illustration 1 g01241523
Schematic for the fuel pump relay
Illustration 2 g01241591
Terminal locations for the ECM connector J1/P1 (P1-28) Fuel pump relay (ground) (P1-70) Keyswitch (+battery)
Illustration 3 g01242249
Terminal locations of relays (1) +Battery "unswitched" (2) Fuel pump relay "ground" (4) +Battery "unswitched" (5) +Battery "switched"Test Step 1. Inspect Electrical Connectors and Wiring
Remove electrical power from the Electronic Control Module (ECM).
Thoroughly inspect the J1/P1 ECM connector and all other connectors in the circuit. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors-Inspect".
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the fuel pump relay.
Check the allen head screw on each ECM connector and the customer connector for the proper torque. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and wiring for abrasion and for pinch points from the sensors back to the ECM.Expected Result:All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion or of pinch points.Results:
OK - Proceed to Test Step 2.
Not OK - Repair: Perform the following 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. Test the Relay in the De-energized State
Disconnect the relay from the circuit.
Verify the operation of the relay in the de-energized state.
Measure continuity across the following terminals of the relay:
Terminal 1 to terminal 3
Terminal 5 to terminal 2
Terminal 1 to terminal 4Note: Refer to Illustration 3 or refer to Illustration 1 for the terminal locations for the relay.Expected Result:The following results were obtained:
Terminal 1 to terminal 3 indicated a short circuit.
Terminal 5 to terminal 2 indicated some measured resistance.
Terminal 1 to terminal 4 indicated an open circuit.Results:
OK - Each measurement was correct. Proceed to Test Step 3.
Not OK - A measurement was incorrect.Repair: Replace the relay and retest the circuit.STOPTest Step 3. Test the Relay in the Energized State
Verify the operation of the relay in the energized state.
Apply 24 VDC across the coil of the relay.
Measure continuity across the following terminals of the relay:
Terminal 1 to terminal 3
Terminal 1 to terminal 4Note: Refer to Illustration 1 or refer to Illustration 3 for the terminal locations for the relay.Expected Result:The following results were obtained:
Terminal 1 to terminal 3 indicated an open circuit.
Terminal 1 to terminal 4 indicated a short circuit.Results:
OK - Each measurement was correct. Proceed to Test Step 4.
Not OK - A measurement was incorrect.Repair: Replace the relay and retest the circuit.STOPTest Step 4. Check the Wiring for a Short Circuit
Check the continuity of each wire on the relay connector for a short circuit.
Determine the routing of each individual wire from the relay connector. Disconnect any connectors. Check for continuity between the wire and every wire on the connector.
Measure continuity between the wire and engine ground.Note: Refer to Illustration 1 or refer to Illustration 3 for the terminal locations for the relay.Expected Result:Each resistance measurement indicated an open circuit.Results:
OK - Each resistance measurement indicated an open circuit. Proceed to Test Step 5.
Not OK - One of the resistance measurements indicated a short circuit.Repair: Repair the wire or replace the wire.STOPTest Step 5. Check the Wiring for an Open Circuit
Check the continuity of each wire on the relay connector for an open circuit.
Determine the routing of each individual wire from the relay connector. Disconnect any connectors.
Create a short between the end of the wires and engine ground.
Measure continuity between the other end of the wires and engine ground.Note: Refer to Illustration 1 or refer to Illustration 3 for the terminal locations for the relay.Expected Result:Each resistance measurement indicated a short circuit.Results:
OK - Each resistance measurement indicated a short circuit. The circuit appears to be operating correctly. Verify that the correct signal voltage is being sent to the coil of the relay. Verify that the supply voltage from the relay is getting to the driven device. Proceed to Test Step 6.
Not OK - One of the resistance measurements indicated an open circuit.Repair: Repair the wire or replace the wire.STOPTest Step 6. Check the Signal Voltage at the ECM
Remove electrical power from the ECM.
Remove the wire from P1-70 (keyswitch) in the P1 ECM connector.
Remove the wire from P1-28 (return) in the P1 ECM connector.
Restore electrical power to the ECM.
Proceed to the "Diagnostic Overrides" screen on Cat ET.
Activate the system for the fuel pump.Note: The diagnostic override will only activate the relay for 120 seconds.
Measure the voltage between the open terminal at P1-70 (Keyswitch) and P1-28 (Fuel Pump Relay (Ground)).
Remove electrical power from the ECM.
Reinstall the wiring to the original configuration.Expected Result:The signal voltage is 24.0 8.0 VDC.Results:
OK - The signal voltage is 24.0 8.0 VDC. The ECM is supplying the correct signal voltage. Proceed to Test Step 7.
Not OK - The signal voltage is not 24.0 8.0 VDC. The ECM is not supplying the correct signal voltage.Repair: Verify your results. Replace the ECM. Refer to electronic troubleshootingTroubleshooting, "Replacing the ECM" before replacing the ECM.Verify that the repair eliminates the problem.STOPTest Step 7. Check the Supply Voltage for the Fuel Pump
Disconnect the harness connector from the fuel pump relay and insert one jumper wire into terminal 5 of the relay and the other jumper wire into terminal 2 of the relay.
Insert the terminal 2 jumper wire into terminal 2 of the harness connector. Insert the terminal 5 jumper wire into terminal 5 of the harness connector.
Restore electrical power to the ECM.
Proceed to the "Diagnostic Overrides" screen on Cat ET.
Activate the relay for the fuel pump.Note: The diagnostic override will only activate the relay for 120 seconds.
Measure the voltage across terminal 1 (+Batt) and terminal 2 (Ground) on the harness connector.Expected Result:T