3512B Petroleum Engines with the ADEM 2 Electronic Control Module Caterpillar

The Engine Speed/Timing Sensors provide engine information to the Electronic Control Module (ECM). The sensor generates a pulse signal. A loss of the signals from the Secondary Engine Speed/Timing sensor and the Primary Engine Speed/Timing sensor causes the ECM to stop sending power to the fuel injectors.

The ECM provides the Engine Speed/Timing Sensor with 12.5 ± 1.0 VDC. A unique tooth on the timing reference gear generates a unique duty cycle. The signal provides the ECM with information on the engine position.

If the Primary Engine Speed/Timing Sensor fails, the ECM will use the Secondary Engine Speed/Timing Sensor until electrical power is removed from the ECM. To prevent any unnecessary down time, the Primary Engine Speed/Timing Sensor should be repaired or replaced at the earliest possible convenience.

Illustration 1	g00863915

Test Step 1. Check for "ACTIVE" Engine Diagnostics.

1. Start the Caterpillar Electronic Technician (ET).

2. Start the engine.

3. Operate the engine until normal operating temperatures are obtained.

Expected Result:

There should be one active Diagnostic Code 261-13.

Results:

• OK - The active Diagnostic Code is 261-13. Proceed to test step 2.

• Not OK - There is more than one active diagnostic code.

  Repair: Repair any active Diagnostic Codes.

  STOP

Test Step 2. Calibrate the Fuel Injection Timing.

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

2. Follow the instructions on the Cat ET screen.

   Note: If the Cat ET screen reads "COULD NOT CALIBRATE", the timing has not been set.

Expected Result:

The Timing Calibration procedure should be successful.

Results:

• OK - The Timing Calibration procedure was completed successfully.

  Repair: Disconnect the timing calibration probe before you exit the "Timing Calibration" screen on the Cat ET. Reset the system and check for any diagnostic codes.

  STOP

• Not OK - The Timing could not be calibrated.

  Repair: Verify that the engine speed was stable during the testing (± 50 rpm). If the engine speed was unstable or the engine speed could not be controlled within ± 50 rpm because of mechanical factors or electrical factors, refer to the diagnostic procedure Troubleshooting, "Engine Misfires, Runs Rough or Is Unstable".If all of the problems have been corrected but the timing can not be calibrated, check the cable of the 6V-2197 Timing Calibration Probe and check the 6V-2197 Timing Calibration Probe in order to verify that the probe is not bent. Verify that the probe is installed correctly before restarting this procedure.

  STOP