821630Q 1 Mercruiser ANODE ASSEMBLY

Illustration 1 g01411138
Schematic for coolant level sensor
Pressurized System: Hot coolant can cause serious burns. To open the cooling system filler cap, stop the engine and wait until the cooling system components are cool. Loosen the cooling system pressure cap slowly in order to relieve the pressure.
Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
Remove electrical power from the ECM.
Thoroughly inspect the connector for the coolant level sensor. Inspect the ECM connector J1/P1. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 2 g01411147
J1/P1 ECM connector (P1-2) Coolant level (P1-29) Digital sensor return (P1-35) +8 V digital supply
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit for the coolant level sensor(s).
Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The connectors and wiring are OK. Proceed to Test Step 2.
Not OK - There is a problem with the connectors and/or the wiring.Repair: Repair the wiring and connectors or replace the wiring or the connectors. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem.Verify that the repair eliminates the problem.STOPTest Step 2. Check the Supply Voltage at the Sensor Connector
Disconnect the coolant level sensor.
Restore electrical power to the ECM.
Turn the keyswitch to the ON position.
Illustration 3 g01159881
Terminal locations at the harness connector for the coolant level sensor (Terminal A) Digital sensor supply (Terminal B) Sensor return (Terminal C) Sensor signal
Measure the voltage between terminals A (+8 VDC) and B (return) at the harness connector for the coolant level sensor.
Turn the keyswitch to the OFF position.Expected Result:The voltage measurement is 8.0 0.4 VDC.Results:
OK - The voltage measurement is 8.0 0.4 VDC. The supply voltage is reaching the sensor. Proceed to Test Step 3.
Not OK - The voltage measurement is not 8.0 0.4 VDC. The digital sensor supply voltage is not reaching the sensor. Proceed to Test Step 8.Test Step 3. Disconnect the Coolant Level Sensor and Monitor the Status of "Coolant Level"
Connect Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
Disconnect the connector for the coolant level sensor.
Turn the keyswitch to the ON position.
Monitor the status of "Coolant Level" on Cat ET.Expected Result:The status changes from "OK" to "Low" when the sensor is disconnected.Results:
OK - The status is "Low" when the sensor is disconnected. Proceed to Test Step 4.
Not OK - The status is "OK" when the sensor is disconnected. Proceed to Test Step 5.Test Step 4. Short the Harness and Monitor the Status of "Coolant Level"
Install a jumper wire between terminals B (return) and C (signal) on the harness connector for the coolant level sensor.
Monitor the status of "Coolant Level" on Cat ET while the jumper wire is installed.
Remove the jumper wire.
Turn the keyswitch to the OFF position.Expected Result:The status changes from "Low" to "OK" when the jumper wire is installed.Results:
OK - The status changes from "Low" to "OK" when the jumper wire is installed. The ECM and the wiring to the coolant level sensor are OK.Repair: Perform the following procedure:
Pressurized System: Hot coolant can cause serious burns. To open the cooling system filler cap, stop the engine and wait until the cooling system components are cool. Loosen the cooling system pressure cap slowly in order to relieve the pressure.
Drain the coolant below the level of the coolant level sensor.
Replace the sensor.
Fill the cooling system according to the procedure in the Operation and Maintenance Manual. Verify that the problem is resolved.STOP
Not OK - Shorting the harness does not affect the status on Cat ET. Proceed to Test Step 5.Test Step 5. Check for Opens in the Wiring
Turn the keyswitch to the OFF position.
Disconnect the J1/P1 ECM connector and the connector for the coolant level sensor.
Measure the resistance between the following terminals:
P1-2 (coolant level sensor) to pin C on the connector for the coolant level sensorExpected Result:The resistance indicates a short circuit.Results:
OK - The resistance indicates a short circuit. There are no opens in the wiring. Proceed to Test Step 6.
Not OK - The resistance indicates an open circuit. There is an open circuit or excessive resistance in the harness or the connectors.Repair: Repair the circuit.Verify that the repair eliminates the problem.STOPTest Step 6. Check the Wiring for a Short CircuitNote: Wiggle the harness during the following measurements in order to reveal an intermittent condition.
Measure the resistance between the points that are listed in Table 1. Be sure to wiggle the wires in the harnesses as you make each resistance measurement.
Table 1
Resistance Measurements for the Circuit for the Coolant Level Sensor    
Con