3BJ-76040-0 Tohatsu STARTER SOLENOID

Illustration 1 g01057652
Ignition transformer and spark plug
(1) Mounting flange
(2) 3-pin connector
(3) Transformer
(4) Extension
(5) Secondary spark plug terminal
(6) O-ring seal
(7) Hole in the spark plug's precombustion chamber The secondary circuit of the transformer provides an initial 8,000 to 37,000 volts to the spark plug. This voltage ionizes the spark plug gap. This voltage is then reduced to about 1000 volts. The total duration of the spark is approximately 400 microseconds.The Electronic Control Module (ECM) can diagnose the primary circuit of the ignition transformers for open circuits and/or for short circuits. Secondary open circuits and short circuits will not directly shut down the engine. However, these conditions may lead to misfire which can cause lugging of the engine. Lugging of the engine can cause a shutdown.Logged diagnostic codes provide a historical record. Before you begin this procedure, use the Caterpillar Electronic Technician (ET) to print the logged codes to a file.Note: Ignition transformers from Electronic Ignition Systems (EIS) are not interchangeable with the transformers in this engine.Caterpillar spark plugs are high voltage devices with internal resistors. The spark plugs operate at a voltage that is greater than 5,000 volts.Most ignition systems are not affected by resistance in the secondary circuit. If a measurement of the resistance is desired, a megohmmeter must be used. A low voltage multimeter will not provide a reliable reading of the resistance because oxidation of the spark plug's internal components will affect the readings of those meters.Test Step 1. Check the Status Screen of Cat ET for the Output of the Secondary Circuits of the Transformers
Illustration 2 g01342726
Junction box
(8) 35 amp circuit breaker
Set the engine control to the OFF/RESET mode. Switch 35 amp circuit breaker (1) to the OFF position.
Connect Cat ET to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
Switch the 35 amp circuit breaker ON. Set the engine control to the STOP mode.
Set up two status screens for Cat ET. Use eight of the following labels for parameters on each status screen:
Table 1
Parameters for the Status Screens on Cat ET
Screen 1
Group 8 Screen 2
Group 9
"Cylinder #1 Transformer Secondary Output Voltage Percentage" "Cylinder #2 Transformer Secondary Output Voltage Percentage"
"Cylinder #3 Transformer Secondary Output Voltage Percentage" "Cylinder #4 Transformer Secondary Output Voltage Percentage"
"Cylinder #5 Transformer Secondary Output Voltage Percentage" "Cylinder #6 Transformer Secondary Output Voltage Percentage"
"Cylinder #7 Transformer Secondary Output Voltage Percentage" "Cylinder #8 Transformer Secondary Output Voltage Percentage"
"Cylinder #9 Transformer Secondary Output Voltage Percentage" "Cylinder #10 Transformer Secondary Output Voltage Percentage"
"Cylinder #11 Transformer Secondary Output Voltage Percentage" "Cylinder #12 Transformer Secondary Output Voltage Percentage"
"Cylinder #13 Transformer Secondary Output Voltage Percentage" "Cylinder #14 Transformer Secondary Output Voltage Percentage"
"Cylinder #15 Transformer Secondary Output Voltage Percentage" "Cylinder #16 Transformer Secondary Output Voltage Percentage"
Start the engine. Apply the normal load at rated speed. Allow the engine to warm up to normal operating temperature.
Observe the value of the output for the secondary circuit of each transformer. Expected Result:The displayed value of the output for the secondary circuit of each transformer is between 1 and 90 percent.Results:
OK - The displayed value of the output for the secondary circuit of each transformer is between 1 and 90 percent. The ignition system components are operating properly.Repair: Investigate other possible root causes of the problem. Troubleshoot the symptom. Refer to Troubleshooting, "Troubleshooting Without A Diagnostic Code".STOP
Not OK - At least one of the outputs displayed a value of 0 percent or a value that is greater than 90 percent. The ignition system components require maintenance. Proceed to Test Step 2.Test Step 2. Inspect the Transformer
Ignition systems can cause electrical shocks. Avoid contacting the ignition system components and wiring.Do not attempt to remove the valve covers when the engine is operating. The transformers are grounded to the valve covers. Personal injury or death may result and the ignition system will be damaged if the valve covers are removed during engine operation. The engine will not operate without the valve covers.
Set the engine control to the OFF/RESET mode. Switch the 35 amp circuit breaker OFF.
Illustration 3 g01342727