G3520B Industrial Engines Caterpillar

Note: Data from a fuel analysis is required for this procedure.

1. Connect the Caterpillar Electronic Technician (ET) to the engine.

2. Verify that the values of the "First Desired Timing" and "Second Desired timing" parameters are according to the recommended timing in the Engine Performance"Fuel Usage Guide". Enter the correct values if the existing values are incorrect.

   Refer to Systems Operation, "Electronic Control System Parameters" for additional information on the "Desired Timing" parameters.

3. Verify that the input for the selection of the base timing is appropriate for the type of gas that is used.
   • If terminal J1-20 is not connected to ground, the Electronic Control Module (ECM) will use the value of the "First Desired Timing" parameter as the base timing.

   • If terminal J1-20 is connected to ground, the ECM will use the value of the "Second Desired Timing" parameter as the base timing.

   If the input is not correct, troubleshoot the circuit for the input. Refer to the electrical schematic for the engine.

4. Start the engine.

5. Use Cat ET to view the "Actual Engine Ignition Timing" status parameter. This parameter is in "Default Status Group 1". Verify that the actual timing is approximately equal to the desired timing.

   Note: The actual timing may vary according to the engine's load, speed, and the detonation level.