5220220KZ Mercruiser END MODEL, +STERN DRIVE BRVII (2.20:1 Ratio)

Illustration 1 g01177672
Schematic for the electrical power supply circuit
Test Step 1. Inspect the Electrical Connectors and the Wiring
Illustration 2 g01144470
Left side engine view (typical example)
Thoroughly inspect connectors (1), the battery connections, and the connections to the keyswitch. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 3 g01177675
P1 ECM connector
(P1-48) +Battery
(P1-52) +Battery
(P1-53) +Battery
(P1-55) +Battery
(P1-61) −Battery
(P1-63) −Battery
(P1-65) −Battery
(P1-67) −Battery
(P1-70) Keyswitch
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the electrical power supply.
Check the allen head screw for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for correct torque values.
Check the harness and wiring for abrasions and for pinch points from the battery to the ECM. Also, check the harness and wiring for abrasions and for pinch points from the keyswitch 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 connectors and the wiring appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem with the connectors and/or the 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.STOPTest Step 2. Check the Battery Voltage at the ECM
Disconnect the J1/P1 ECM connector.
Turn the keyswitch to the ON position.
Measure the voltage between P1-48 Unswitched +Battery and P1-61 -Battery.
Measure the voltage between P1-52 Unswitched +Battery and P1-63 -Battery.
Measure the voltage between P1-53 Unswitched +Battery and P1-65 -Battery.
Measure the voltage between P1-55 Unswitched +Battery and P1-67 -Battery.
Measure the voltage between P1-70 keyswitch and P1-63 -Battery. Expected Result:The measured voltage is between 22.0 VDC and 27.0 VDC with no suspected intermittent problems at this time.Results:
OK - The ECM is receiving the correct voltage.Repair: If an intermittent condition is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - The battery voltage is not within specifications. Proceed to Test Step 3.
Not OK - The voltage at the keyswitch is not within specifications.Repair: Trace the wiring for the keyswitch from the ECM through the keyswitch circuit to the batteries. Find the problem and repair the problem. Check the circuit protection for the circuit and for the wiring. Verify that the repairs eliminate the problem.STOPTest Step 3. Check the Batteries
Measure no-load battery voltage at the battery posts.
Load test the batteries. Use the 4C-4911 Battery Load Tester. Refer to Special Instruction, SEHS9249, "Use of 4C-4911 Battery Load Tester for 6, 8 and 12 Volt Lead Acid Batteries" and Special Instruction, SEHS7633, "Battery Test Procedure". Expected Result:The batteries pass the load test. The measured voltage is the minimum specification for a 24V system.Results:
OK - The batteries are OK.Repair: Check the wiring between the batteries and the ECM for shorts.Check the connectors between the batteries and the ECM for moisture and/or corrosion.Repair the wiring and/or the connectors.Verify that the repair eliminates the problem.STOP
Not OK - The battery voltage is low or the battery did not pass the load test.Repair: Recharge or replace the faulty batteries. Verify that the repair eliminates the problem.STOP