G3520B Industrial Engines Caterpillar

The master Electronic Control Module (ECM) has the ability to calibrate the mechanical differences between the Top Center (TC) of the flywheel and the TC of the timing gear on the left rear camshaft gear. A magnetic transducer signals the TC of the flywheel to the master ECM when the TC hole on the flywheel passes beneath the transducer. The engine speed/timing sensor signals the TC of the timing gear to the master ECM. Any offset between the TC of the flywheel and the TC of the timing gear is stored into memory. The master ECM communicates the information from the calibration to the slave ECM via the Cat Data Link.

Calibration of the timing is required only after the following circumstances:

• The master ECM has been replaced.

• The timing gear and/or the rear gear train have been adjusted.

• The timing gear and/or the rear gear train have been replaced.

Note: The 261-13 Engine Timing calibration required is generated only for a master ECM that has never performed a timing calibration.

The calibration procedure is initiated with the Caterpillar Electronic Technician (ET).

1. Installation of the Transducer
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   Illustration 1	g01410002
   Location of the connectors for the timing calibration (terminal box for the master ECM) (1) P50 connector for the timing calibration probe (2) Terminal box for the master ECM (3) Service tool connector

   1. Set the engine control to the OFF/RESET position. Install one end of 7X-1695 Cable As to P50 connector (1) that is located inside terminal box (2) for the master ECM.

   2. Connect Cat ET to service tool connector (3). Refer to Troubleshooting, "Electronic Service Tools".
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   Illustration 2	g01410072
   Installation of the timing calibration probe (typical example) (4) 6V-3093 Transducer Adapter (5) 6V-2197 Transducer (6) Timing calibration port in the flywheel housing (7) Timing hole in the flywheel

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   NOTICE
   The timing hole (7) in the flywheel must not be aligned with the transducer during installation. If the transducer is installed into the hole of the flywheel, the transducer will be damaged on engine start-up. Rotate the flywheel for more than 10 degrees before or after the TC position in order to move the flywheel hole away from the hole in the flywheel housing that is for the transducer. Always confirm that the holes are not aligned prior to installation of the transducer.

   3. Remove the timing calibration plug from the timing calibration port on either side of the flywheel housing. Install 6V-3093 Transducer Adapter (4) into timing calibration port (6).

      Note: Ensure that the hole in the flywheel housing for the transducer is not aligned with the timing hole in the flywheel.

   4. Remove the protective end cap from the 6V-2197 Transducer (5). Insert the transducer into the adapter until the transducer contacts the surface of the flywheel. Pull the transducer away from the surface of the flywheel until the tip of the transducer is 1 mm (0.04 inch) away from the flywheel. Tighten the nut on the adapter in order to secure the transducer in place.

   5. Connect the loose end of the 7X-1695 Cable As to the connector for the transducer.

2. Calibration

   1. Start the engine. Use Cat ET to establish communications with the master ECM.

   Note: A two-step process is used to calibrate the signal for the speed/timing sensor. The new timing reference is calculated first. The reference is based on the signals from the transducer and the speed/timing sensor. Next, the new timing reference is programmed into the permanent memory of the master ECM.

   2. Operate the engine at the rated speed and load.

   3. Select "Service" from the main menu on Cat ET. Select "Calibrations" from the menu. Select "Timing Calibration".

   4. Use either of the following methods in order to initiate the calculation of the new timing reference:
      • Press the space bar on the keyboard of the Personal Computer (PC).

      • Click the left mouse button on the "Continue" button in the lower left corner of the Cat ET screen.

      Cat ET will indicate "Please wait...Calculating the new Timing Reference". After a few moments, Cat ET will display "The ECM has calculated the Timing Reference" and "Choose the Continue button to program the Timing Reference".

   5. Use either of the following methods in order to program the new timing reference:
      • Press the space bar on the keyboard of the PC.

      • Click the left mouse button on the "Continue" button in the lower left corner of the Cat ET screen.

      Successful Calibration

      After a few moments, Cat ET displays "CALIBRATION SUCCESSFUL".

      Disconnect the transducer and the cable. Remove the adapter and reinstall the timing calibration plug. Replace the protective cover on the transducer. The calibration is complete.

      Unsuccessful Calibration

      After a few moments, Cat ET displays "COULD NOT CALIBRATE".

      Verify that the engine rpm was stable during the calibration (± 50 rpm). Verify that there are no active diagnostic codes which can prevent the calibration. Repeat the calibration procedure.

      If the calibration is still unsuccessful, check the installation of the tools and the operation of the tools. Check the 7X-1695 Cable As for continuity. Verify that the transducer is not bent, open, or shorted internally. Repeat the calibration procedure.

      Excessive backlash in the gear train will cause an inconsistent timing signal. Refer to Disassembly and Assembly for identifying and repairing a gear train problem.