20741620 Volvo.Penta Hollow screw

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Schematic
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P1 ECM connector (P1-4) +8 V digital supply (P1-5) Digital return (P1-46) Coolant level (PM102Y) (P1-66) Throttle position
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Sensor connectorTest Step 1. Inspect Electrical Connectors and Wiring
Remove the electrical power from the ECM.
Thoroughly inspect the J1/P1 ECM connector, the machine connector, the connector for the throttle position sensor and the connector for the coolant level sensor. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
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 ECM connector (allen head screw) for the proper torque. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
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 for Active Diagnostic Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Restore the electrical power to the ECM.
Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.Note: Wait at least 30 seconds in order for the diagnostic codes to become active.Expected Result:One of the following diagnostic codes is active:
41-03
41-04 Results:
OK - A -03 diagnostic code is active. Proceed to Test Step 3.
OK - A -04 diagnostic code is active. Proceed to Test Step 4.
Not OK - No diagnostic code for the digital supply is active. A problem is suspected with a sensor output signal. In order to verify that the sensor is receiving the correct supply voltage, proceed to Test Step 3.Test Step 3. Check the Voltage on the +8 V Supply Wire
Remove the electrical power from the ECM.
Disconnect all of the digital sensor at the sensor connectors.
Restore the electrical power to the ECM.
Measure the voltage between terminal A and terminal B at each sensor connector.Expected Result:The