CONTROL GP-GENERATOR SET 5034421 - Caterpillar

Illustration 2 g01438044
Schematic for the primary circuit and for the secondary circuit
There is a strong electrical shock hazard when the crankshaft is rotating.Do not touch the wires that are associated with the ignition system when the engine is cranking or when the engine is running.
Illustration 3 g01438062
Section view of an ignition transformer and front view of the transformer's connector
(8) Mounting flange
(9) Terminal for the spark plug's extension
(A) Transformer's circuit driver
(B) Transformer's return
(C) Unused
Illustration 4 g00754013
Symbol for a diode
Table 6
Troubleshooting Test Steps Values Results
4. Test the Primary Circuit of the Transformer
A. Check the primary circuit by measuring the voltage drop across the blocking diode.
Note: The polarity of the leads is not important for the first measurement.
B. Set the multi-meter to the diode scale.
C. Connect the multi-meter leads across the following terminals:
- Terminal A and Terminal B
Refer to Illustrations 2 and 3 for the correct locations.
D. Record the voltage that is indicated by the meter.
E. Reverse the polarity of the multi-meter leads.
F. Record the voltage that is indicated by the meter.
Primary Circuit
Result: The transformer is OK.
One measurement indicates approximately 0.450 V. The other measurement indicates an open circuit.
Proceed to Test Step 5.
Result: The transformer is NOT OK.
At least one of the measurements is incorrect.
Repair: Replace the ignition transformer. Ensure that the specified transformer for the specific engine application is used.
If the problem is not resolved, proceed to Test Step 5.
Illustration 5 g00863850
Resistance versus temperature
(Y) Resistance in Ohms
(X) Temperature in degrees Celsius (degrees Fahrenheit)
Table 7
Troubleshooting Test Steps Values Results
5. Test the Secondary Circuit of the Transformer
Note: The resistance of the secondary coil will vary with the temperature.
A. Measure the resistance of the secondary circuit.
Refer to Illustration 1 for a measured resistance that is within 1,000 Ohms is acceptable.
B. Set the multi-meter to the 40,000 Ohm scale.
C. Connect the leads of the multi-meter between mounting flange (2) and secondary connection (5).
D. Measure the resistance between the mounting flange and the connector for the spark plug. Refer to Illustration 1 for the correct locations.
Secondary Circuit
Result: The transformer is OK.
The measurement is within the acceptable tolerance.
Proceed to Test Step 6.
Result: The transformer is NOT OK.
The measurement is not within the acceptable tolerance.
Repair: Replace the ignition transformer. Ensure that the specified transformer for the specific engine application is used.
If the problem is not resolved, proceed to Test Step 6.
6. Start the Engine and Check the Output of the Transformers
A. Install the spark plug according to the instructions in the engine's Operation and Maintenance Manual.
B. Install the transformer and the valve cover.
C. Reset the control system. Clear any logged diagnostic codes.
D. Start the engine.
E. Allow the engine to warm up to normal operating temperature.
F. Apply the normal load at rated speed.
G. Use Cat ET to check the value of the output for the secondary circuit of each transformer.
Output Voltage
Result: The output from each transformer is OK.
Return to service.
Result: The output of at least one transformer is NOT OK.
Proceed to Test Step 7.
7. Isolate the Spark Plug and the Transformer
A. Switch the affected transformer with a transformer that is known to