BLOCK 3C8674 - Caterpillar

Illustration 5 g01204728
P2 ECM connector
(P1-15) SCAC coolant level sensor
(P1-30) Engine coolant level sensor
(P2-57) +8 V digital supply
(P2-66) Digital sensor return
(P2-65) +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.
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.
Illustration 6 g01132478
Harness connector for the coolant level sensor
(A) +8 VDC
(B) Return
Measure the voltage between terminals A (+8 VDC) and B (return) at the harness connector for the coolant level sensor.
Remove electrical power from the ECM. 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.Repair: Refer to Troubleshooting, "Digital Sensor Supply Circuit - Test".STOPTest Step 3. Disconnect the Coolant Level Sensor and Monitor the Status of "Coolant Level"
Connect the Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
Disconnect the coolant level sensor connectors.
Restore electrical power to the ECM.
Monitor the status of "Coolant Level" on Cat ET.
Remove electrical power from the ECM. 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"
Restore electrical power to the ECM and monitor the status of "Coolant Level" on Cat ET.
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.
Remove electrical power from the ECM. 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