- Turn the engine control switch to the OFF/RESET position. Switch the circuit breaker for the engine OFF.
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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. |
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- Remove the valve cover of the suspect cylinder.
- Disconnect the ignition harness from the transformer. Remove the transformer from the engine.
| NOTICE |
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Pulling on the wiring harness may break the wires. Do not pull on the wiring harness. |
- Inspect the body of the transformer and ground spring (2) for corrosion and/or damage. Verify that screws (1) for the ground spring are secure.
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| Illustration 1 | g00715304 |
(1) Screw (2) Ground spring (3) Spacer (4) Terminal for the spark plug (5) Extension (6) O-ring seal | |
- Check the extension near spacer (3) for signs of punch through (pin holes) and/or arcing.
Note: Punch through is caused by misfire in the engine that does not generate a diagnostic code.
- Inspect O-ring seal (6) inside the extension for damage and for deterioration. The seal must be pliable. If the seal is hard, install a new seal.
- Remove O-ring seal (6) . Inspect terminal (4) inside the extension for looseness, for corrosion, and/or for damage. Insert an extra spark plug into the transformer and check for spring pressure of terminal (4) .
- Clean any deposits from the inside of the extension. Use a 6V-7093 Brush with isopropyl alcohol.
| NOTICE |
|---|
The extension can be scratched and damaged with a wire brush. Do not use a wire brush on the extension. |
- Use a multimeter to check the primary circuit.
- Set the multimeter to the diode scale. Measure the voltage between positive terminal (7) and negative terminal (8) . The polarity of the leads is not important.
Show/hide table
Illustration 3 g00754013
Symbol for a diode
- Reverse the polarity of the probe and measure the voltage between the terminals again.
For the primary circuit, one of the voltage measurements is approximately 0.450 VDC. The other measurement is an open circuit.
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| Illustration 2 | g00814314 |
(1) Screw (4) Terminal connector (7) + Terminal (8) - Terminal | |
- Measure the resistance of the secondary circuit.
- Set the multimeter to the 40,000 Ohm scale. Measure the resistance between screw (1) for the ground spring and terminal (4) for the spark plug.
Illustration 4 is a graph for the resistance of the following transformers: 165-1591 , 165-1592 , 213-7443 and 213-7444
Illustration 5 is a graph for the resistance of the following transformers: 232-6348 , 232-6349 , 232-6352 and 232-6353
- Set the multimeter to the 40,000 Ohm scale. Measure the resistance between screw (1) for the ground spring and terminal (4) for the spark plug.
Note: The resistance of the secondary coil will vary with the temperature. Illustrations 4 and 5 demonstrate the relationship between the secondary coil's resistance and the temperature. A reading that is within ± 1000 ohms is acceptable.
- Switch the suspect transformer with a transformer from a different cylinder that is known to be good. Install the transformers. Install the valve covers.
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| Illustration 4 | g00863850 |
(Y) Resistance in ohms (X) Temperature in degrees Celsius (degrees Fahrenheit) | |
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| Illustration 5 | g01170387 |
- Reset the control system. Clear any logged diagnostic codes.
- Start the engine and operate the engine in order to generate a diagnostic code.
If the problem follows the transformer, replace the transformer. Make sure that you use the correct transformer for the engine. Reset the control system. Clear any logged diagnostic codes.
If the problem stays with the cylinder, there is a problem with the spark plug or with the electrical circuit for the transformer.
For troubleshooting of the electrical circuit, refer to the engine's Electronic Troubleshooting manual.
For instructions on inspection and replacement of the spark plug, refer to the engine's Operation and Maintenance Manual.