5121700LP Mercruiser STERN DRIVE, (2.40:1 RATIO)

Table 1
Diagnostic Codes Table    
Code and Description    Conditions which Generate this Code    System Response    
261-13 Engine Timing Calibration calibration required     The engine speed/timing sensor has not been calibrated.     This will not keep the engine from running.    
277-8 Timing Calibration Sensor abnormal frequency, pulse width, or period     The engine speed is above low idle.
The timing calibration sensor does not send a valid signal for five engine revolutions.
If a signal is present, the signal varies more than 30 degrees.     The code is logged.
This will not keep the engine from running.    The engine speed/timing sensors provide engine information to the 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, replace the primary engine speed/timing sensor at the earliest possible convenience.Check for active diagnostic codes and/or for logged diagnostic codes. Troubleshoot any diagnostic codes that are present before continuing with this procedure.
Install the Timing Calibration Probe.
Remove electrical power from the ECM.
Remove the timing calibration plug from the flywheel housing.
Examine the flywheel through the timing calibration hole. Ensure that the probe is not inserted into the timing pin hole. If necessary, rotate the engine crankshaft.
Install the 6V-3093 Transducer Adapter into the hole for the timing calibration at the flywheel.
Insert the 6V-2197 Magnetic Transducer through the 6V-3093 Transducer Adapter. Insert the transducer until contact is made with the surface of the flywheel. Move the transducer 0.9 mm (0.04 inch) away from the flywheel.
Do not install the timing calibration probe over the timing pin hole at the flywheel or damage will result.
Tighten the nut on the 6V-3093 Transducer Adapter .
Connect the 7X-1695 cable from the engine timing calibration probe to the connector P26.
Restore electrical power to the ECM.
Start the engine. Allow the engine to exit cold mode operation.
Calibrate the Fuel Injection Timing.
Select "Calibrations" from the "Service" menu on Caterpillar Electronic Technician (ET). Select the "Timing Calibration" from the "Calibrations" menu. Note: Engine speed will be set to 800 rpm by the ECM during the calibration.
Follow the instructions on the Cat ET screen.Note: If the Cat ET screen reads "Could Not Calibrate", the timing has not been set. 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, verify that the probe is not bent. Verify that the probe is installed correctly before restarting this procedure.