855387 Mercruiser SUPPORT-OIL TANK

Illustration 1 g00810701
Schematic for the Compression Brake CircuitTest Step 1. Check for Connector Damage
Turn the keyswitch to the OFF/RESET position.
Check J1/P1 and J2/P2 ECM connectors, J300/P300 injector connector, and the associated wiring for the following problems: damage, corrosion, abrasion and incorrect attachment. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.Expected Result:The connectors and wiring should be free of the following problems: damage, corrosion, abrasion and incorrect attachment.Results:
OK - Proceed to Test Step 2.
Not OK - Repair: Repair the circuit.Verify that the repair eliminates the problem.STOPTest Step 2. Check for Active/Logged Diagnostic Codes on ET
Connect ET to the service tool connector.
Turn the keyswitch to the ON position.
Observe any diagnostic codes on ET.
Turn the keyswitch to the OFF/RESET position.Expected Result:The following diagnostic codes should not be active or logged:
791-05 Jake Brake Low/High Solenoid open circuit
791-06 Jake Brake Low/High Solenoid short to ground
792-05 Jake Brake Medium/High Solenoid open circuit
792-06 Jake Brake Medium/High Solenoid short to ground
788-02 Loss of Engine Retarder Selector Switch SignalResults:
No Diagnostic Codes - No diagnostic codes are present.Repair: If an intermittent problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
791-05, 791-06, 792-05, or 792-06 - Diagnostic codes are present for the solenoids. Proceed to Test Step 3.
788-02 - A diagnostic code is present for the switch. Proceed to Test Step 8.Test Step 3. Test the Compression Brake Solenoids by using ET
Turn the keyswitch to the ON position.
Activate the "Jake Brake Low/High" override and the "Jake Brake Med/High Override". Listen for the compression brake solenoids to click as the solenoids are activated by ET.
Turn the keyswitch to the OFF/RESET position.Expected Result:Each of the compression brake solenoids should click as the solenoid is activated by ET.Results:
OK - The solenoids are operating normally.Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.STOP
Not OK - Proceed to Test Step 4.Test Step 4. Test the Engine Harness with ET
Disconnect the connector J300/P300 at the valve cover base.
Turn the keyswitch to the ON position.
Install a test light between P300:7 (Compression Brake Solenoid Return) and P300:9 (Compression Brake Solenoid LOW/HIGH).
Activate the "Jake Brake Low/High" override and observe the test light. The test light should illuminate when the override is active.
Move one of the leads on the test light from P300:9 (Compression Brake Solenoid LOW/HIGH) to P300:11 (Compression Brake Solenoid MED/HIGH). Leave the other lead connected to P300:7 (Compression Brake Solenoid Return).
Activate the "Jake Brake Med/High" override and observe the test light. The test light should illuminate when the override is active.
Turn the keyswitch to the OFF/RESET position.
Remove the test light and reconnect the connector J300/P300 at the valve cover.Note: Additional diagnostic codes will be generated because the connector J300/P300 was disconnected at the valve cover and the overrides were activated. Clear the additional diagnostic codes upon completing this test.Expected Result:The test light should illuminate when the override is active. The test light should otherwise remain off.Results:
OK - The engine harness is operating normally.Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent. Proceed to Test Step 6.
Not OK - Proceed to Test Step 5.Test Step 5. Check the ECM
Connect ET to the service tool connector.
Turn the keyswitch to the OFF position.
Connect a 140-2266 Adapter Cable (70 Pin Breakout) to the ECM connector J2/P2.
Turn the keyswitch to the ON position.
Install a test light between P2:9 (Compression Brake Solenoid Return) and P2:11 (Compression Brake Solenoid LOW/HIGH) at the breakout.
Activate the "Jake Brake Low/High" override and observe the test light. The test light should illuminate when the override is active.
Move one of the leads on the test light from P2:11 (Compression Brake Solenoid LOW/HIGH) to P2:10 (Compression Brake Solenoid MED/HIGH) on the breakout. Leave the other lead connected to P2:7 (Compression Brake Solenoid Return).
Activate the "Jake Brake Med/High" override and observe the test light. The test light should illuminate when the override is active.
Turn the keyswitch to the OFF/RESET position.
Remove the test light and the breakout, and reconnect the ECM connector J2/P2.Note: Additional diagnostic codes will be generated because the ECM engine harness connector J2/P2 was disconnected and the overrides were activated. Clear the additional diagnostic codes upon completing this test.Expected Result:The test light should illuminate when the overrides are active. The test light should otherwise remain off.Results:
OK - The test light illuminates when the overrides are active, and the ECM is working properly.Repair: There is an open or a short between the ECM and the connector P300. Repair the circuit.Verify that the repair eliminates the problem.STOP
Not OK - The ECM does not appear to be functioning properly.Repair: Verify your results. Replace the ECM. Refer to Troubleshooting, "Replacing the ECM" before replacing the ECM.STOPTest Step 6. Check for Damage to the Wiring Harness that is Under the Valve Cover
Check J300 harness connector, the solenoid connectors, and the associated wiring that is under the valve cover for the following problems: damage, corrosion, abrasion and incorrect attachment. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.Expected Result:The connectors and wiring should be free of the following problems: damage, corrosion, abrasion and incorrect attachment.Results:
OK - Proceed to Test Step 7.
Not OK - Repair: Repair the circuit.Verify that the repair eliminates the problem.STOPTest Step 7. Test the Wiring Harness that is Under the Valve Cover by using ET
Disconnect the wiring harness from all of the compression brake solenoids that do not respond when the "Jake Brake Low/High" override and the "Jake BrakeMed/High" override are activated.
Turn the keyswitch to the ON position.
On the wiring harness, install a test light between one pair of terminals that was disconnected from the solenoid. Only one pair of terminals should be tested at a time. Note: Take proper steps in order to prevent any of the terminals from shorting to the engine while the following test is performed.
Activate the "Jake Brake Low/High" override and the "Jake BrakeMed/High" override. Observe the test light. The test light should illuminate when the overrides are active.
Repeat the above steps for all other pairs of terminals that have been disconnected from the solenoid.
Turn the keyswitch to the OFF/RESET position.
Remove the test light and reconnect the