SEAL 2528296 - Caterpillar

The Engine Control Module (ECM) detects the following conditions:
The secondary engine speed/timing signal was lost and then returned within one second.
The engine has been running for more than three seconds.
The engine speed did not pass through the 350 to 500 rpm range.
The battery voltage is more than 9 VDC for at least two seconds prior to the loss of signal.System Response:The ECM will use the primary speed/timing sensor to calculate the engine speed. "DIAG" will be displayed next to the status for "Engine Speed" on Caterpillar Electronic Technician (ET). The check engine lamp will not be illuminated for this code unless the code has been active for ten hours. The code is logged.Possible Performance Effect:The performance will not be affected unless both sensor signals are lost. The loss of both timing sensor signals will cause the ECM to shut down the engine.Troubleshooting:Test Step 1. Perform the following diagnostic procedure: "Engine Speed/Timing Sensor Circuit - Test"Results:
OK - STOP