31375826 Volvo.Penta Crankshaft

Illustration 1 g00664509
Test Step 1. Check if the "G" Pin is Grounded.
Remove power from the TCM.
Disconnect the ignition harness from the magneto.
Use the 4000 ohm scale to measure the resistance between pin G of the ignition harness and the -battery.Expected Result:The resistance is greater than 1000 ohms.Results:
OK - No external device is grounding the magneto. Proceed to test step 2.
Not OK - An external device is grounding the magneto.Repair: Locate the device and reset the device. Stop.
Not OK - There is a short circuit in the wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Stop.Test Step 2. Check for an Open Circuit.
Disconnect the MIB from the harness.
Apply power to the system. Place the engine control switch in the "STOP" position.
Use the 400 ohm scale to measure the resistance at the connector for the MIB on the engine harness from pin H to the -battery.Expected Result:The resistance is less than two ohms.Results:
OK - Proceed to test step 3.
Not OK - There is a problem in the wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Stop.Test Step 3. Check for Connector Damage.
Remove power from the timing control system.
Check the connections of the MIB for the following problems: damage, corrosion and mechanical failure. Refer to Troubleshooting, "Inspecting Electrical Connectors".
Check the connection of the TCM for the following problems: damage, corrosion and mechanical failure.
Check the connector for the ignition harness at the magneto for the following problems: damage, corrosion and mechanical failure.
Check the connectors from the MIB to the magneto for the following problems: damage, corrosion and mechanical failure.
Check the connections for the ignition transformer at the ignition harness for the following problems: damage, corrosion and mechanical failure.Expected Result:The components and wiring are free of the following problems: damage, corrosion and mechanical failure.Results:
OK - The components are in good condition. Proceed to test step 4.
Not OK - The components require service.Repair: Repair the components or wiring and/or replace the components or wiring. Stop.Test Step 4. Check the Ground Connections.
Inspect the ground strap at the MIB.
Verify that there is no paint between the ground strap and the engine block.
Verify that there is no paint between the ground strap and the MIB.
Check the ground wire connection on the back of the magneto.Note: The wire is part of the engine harness. The wire is connected to the housing of the magneto with a bolt.
Check the ground connections to the engine block at the ignition harness for the following problems: damage, corrosion and mechanical failure.Results:
OK - The ground connections are OK. Proceed to test step 5.
Not OK - The ground requires service.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Stop.Test Step 5. Check the Engine Harness for Opens.
Use the 400 ohm scale on the multimeter to check the continuity in the engine harness. Check the continuity between the points that are listed in Table 1:
Table 1
Continuity Check of the Engine Harness    
Pin A of the MIB (1)     Pin "c" of the TCHC (2)    
Pin B of the MIB     Magneto Case    
Pin C of the MIB     Pin "e" of the TCHC    
Pin E of the MIB     Pin G of the TCHC    
Pin G of the MIB     Pin H of the TCHC    
( 1 ) Magneto Interface Box
( 2 ) Timing Control Harness ConnectorExpected Result:The readings are less than 2 ohms.Results:
OK - The engine harness does not have an open circuit. Proceed to test step 6.
Not OK - The engine harness has an open circuit.Repair: Repair the fault in the harness or replace the harness. Stop.Test Step 6. Check for Short Circuits.
Use the 4000 ohm scale to measure the resistance at the Timing Control Harness Connector (TCHC). Check between the points that are listed in Table 2:
Table 2
Timing Control Harness Connector (TCHC)
Check for Short Circuits    
Pin N     Pin "c"    
Pin "e"
Pin G
Pin H
Measure the resistance between all the pins on the engine harness connector for the MIB.Expected Result:The resistance is greater than 1000 ohms.Results:
OK - No short circuits are found. Proceed to test step 7.
Not OK - There is a problem in the wiring harness.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Stop.Test Step 7. Check the Magneto.
Reconnect all of the connectors except the connector to the magneto for the ignition harness.
Set the multimeter on the 200 VDC scale.
Measure the voltage at the magneto from pin G to the magneto case.
Crank the engine while you measure the voltage.Note: Crank the engine at 120 rpm.
If you use the 9U-6958 Magneto Test Module, connect the module to the magneto.
Measure the voltage from the odd number bank DC output to ground.Expected Result:The voltage is greater than 100 VDC.Results:
OK - The magneto is OK.Repair: Replace the MIB. Reset the system. If the fault returns replace the TCM. Stop.
Not OK - The magneto has failed. Repair: Replace the magneto. Stop.