864375T05 Mercruiser ECM, Engine Control Module

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Schematic for the air inlet heaterTest Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
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Component locations for the air inlet heater (1) Air inlet heater (2) Air inlet heater relay (3) Ground connection for the air inlet heater (4) J2/P2 connectors
Thoroughly inspect the J501/P501 air inlet heater relay connectors and connector (4). Inspect the connections on air inlet heater relay (2) and air inlet heater (1). Refer to Troubleshooting, "Electrical Connectors - Inspect".
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P2 terminals that are associated with the air inlet heater (P2-5) Air inlet heater (P2-79) Air inlet heater
Perform a 45 N (10 lb) pull test on each of the wires in the connectors that are associated with the circuit.
Check the torque of the allen head screws for the ECM connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and wiring for abrasion and for pinch points from the air inlet heater back to the ECM and from the air inlet heater back to the battery.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 harness and the connectors 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 and/or the wiring. Replace parts, if necessary. 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 the Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
Turn the keyswitch to the ON position.
Observe the "Active Diagnostic" screen on Cat ET. Wait at least 15 seconds so that any codes may become active. Look for these codes:
617-05
617-06Expected Result:One of the above codes is active.Results:
Active 617-05 code - A 617-05 diagnostic code is active. Proceed to Test Step 3.
Active 617-06 code - A 617-06 diagnostic code is active. Proceed to Test Step 5.
No active codes - None of the above codes are active. There may be a problem with the high power circuit. Proceed to Test Step 6.Test Step 3. Check for an Open Circuit to the Relay
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Small terminals for the typical air inlet heater relay
Disconnect the wires from the small terminals of the air inlet heater relay.
Install a test lamp across the wires.
Start the "Air Inlet Heater Override" on Cat ET and observe the test lamp.Note: Do not leave the "Air Inlet Heater Override" ON. This prevents unnecessary cycling of the air inlet heater and the battery from discharging. The "Air Inlet Heater Override" has a one minute timer that disables the test when the time expires.
Stop the "Air Inlet Heater Override" and turn the keyswitch to the OFF position.Expected Result:The test lamp turned on while the override was active.Results:
OK - The test lamp turned on while the override was active. The open circuit is in the relay.Repair: Replace the air inlet heater relay. Clear any diagnostic codes. Verify that the problem is resolved.STOP
Not OK - The test lamp did not turn on while the override was active. Proceed to Test Step 4.Test Step 4. Check the Wiring Between the ECM and the Relay
Disconnect the J2/P2 connectors.Note: Be sure to wiggle the harness during the following measurements in order to reveal an intermittent condition.
Measure the resistance between terminals P2-5 and P501-1.
Measure the resistance between terminals P2-79 and P501-2.Expected Result:Both of the resistance measurements are less than ten Ohms.Results:
OK - Both of the resistance measurements are less than ten Ohms.Repair: Connect the wires to the relay's small terminals. Replace the ECM. Refer to Troubleshooting, "Replacing the ECM".STOP
Not OK - At least one of the resistance measurements is more than ten Ohms. There is a problem with the wiring between the ECM and the air inlet heater relay. There may be a problem with a connector.Repair: Repair the wire and/or the connector, when possible. Replace parts, if necessary. Verify that the problem is resolved.STOPTest Step 5. Check for a Short Circuit in the Wiring to the Relay
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Small terminals for the typical air inlet heater relay
Disconnect the wires from the small terminals for the air inlet heater relay.
Turn the keyswitch to the ON position.
Observe the "Active Diagnostic" screen on Cat ET. Wai