20353 Mercury STUD, REED BLOCK AND CARBURETOR

Illustration 1 g01250331
Schematic for the electrical power supply circuit
Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the battery disconnect switch to the OFF position.
Turn the keyswitch to the OFF position.
Illustration 2 g01186024
Location of the J1/P1 ECM connectors (typical left side engine view)
Thoroughly inspect theJ1/P1 ECM connectors. Also, thoroughly inspect the machine connector. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 3 g01250340
Terminal locations at the P1 ECM connector
(P1-48) +Battery
(P1-52) +Battery
(P1-53) +Battery
(P1-61) −Battery
(P1-63) −Battery
(P1-65) −Battery
(P1-70) Keyswitch
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors that are associated with the circuit.
Check the allen head screw for each of the ECM connectors and the machine connectors for the proper torque. Refer to 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 inserted and coupled. The harness and wiring are free of corrosion, of abrasion, and of pinch points. All connections and grounds are tight and free of corrosion.Results:
OK - The harness and connectors appear to be 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 Battery Voltage at the ECM
Disconnect the J1/P1 ECM connector.
Turn the battery disconnect switch to the ON position.
Turn the keyswitch to the ON position.
Measure the voltage between terminals 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 P1-70 (keyswitch) and P1-63 (−Battery).
Turn the keyswitch to the OFF position. Expected Result:The measured voltage is between 22.0 VDC and 27.0 VDC.Results:
OK - The ECM is receiving the correct voltage at this time.Repair: There may be an intermittent electrical problem in the circuit. If an intermittent problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - The voltage is not correct at the ECM. There is a problem in the circuit for the battery power. There may be a problem with the batteries. Proceed to Test Step 3.
Keyswitch voltage out of range - There is a problem in the circuit for the keyswitch. Proceed to Test Step 4.Test Step 3. Check the Batteries
Measure the 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 12V or 24V system.Results:
OK - The batteries are OK.Repair: There is an open circuit or excessive resistance in the wiring or connections between the batteries and the ECM. Verify that the circuit protection is OK. Check the connections at the machine connector. Verify that the connection for the engine ground is clean and tight and that the battery disconnect switch is functioning properly. Repair the connectors or wiring and/or replace the connectors or wiring. 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.STOPTest Step 4. Check the Voltage from the Keyswitch to the ECM
Remove the wire from the terminal R of the keyswitch.
Turn the keyswitch to the ON position.
Measure the voltage on terminal B of the keyswitch to engine ground.
Measure the voltage on terminal R of the keyswitch to engine ground.
Turn the keyswitch to the OFF position. Expected Result:Voltage is present on terminal B and terminal R at the keyswitch.Results:
OK - Voltage is present on terminal B and terminal R at the keyswitch.Repair: The problem is in the wiring harness between the keyswitch and the ECM connector. Repair the circuit. Replace parts, if necessary. Verify that the problem is eliminated.STOP
Not OK - Voltage is not present on terminal B at the keyswitch.Repair: If voltage is not present on terminal B, repair the wire between the +Battery and the keyswitch. Verify that the circuit protection for the keyswitch is OK. Verify that the problem is eliminated.STOP
Not OK - Voltage is not present on terminal R at the keyswitch.Repair: If voltage is present on terminal B of the keyswitch but not present on terminal R, there is a problem with the keyswitch. Replace the keyswitch. Return all wiring to the original configuration. Verify that the problem is eliminated.STOP