PUMP & MOUNTING GP 4778411 - Caterpillar

The Engine Control Module (ECM) detects the following condition:
The "VSL Protection" is not programmed to "TEL".
The ECM does not detect vehicle speed when conditions indicate that vehicle speed should be present.
Desired engine speed is greater than the programmed "VSL Protection".System Response:The ECM will limit engine rpm to the programmed "VSL Protection". If the ECM is providing the speedometer signal, the speedometer will reflect the loss of speed when the vehicle is moving and the problem occurs. Caterpillar Electronic Technician (ET) will display "DIAG" next to "Vehicle Speed" on the status screen while the diagnostic code is active. The check engine lamp will illuminate.Possible Performance Effect:The driver may think that the engine power is low and that the engine is unable to reach the expected rpm.Note: A fuel system restriction has been known to cause this diagnostic code although this occurrence is not common. This situation exists because the injectors are unable to provide sufficient fuel in order to achieve the desired rpm under normal load conditions. Because the ECM cannot reach the desired rpm under the normal load conditions, the ECM suspects that the vehicle is under load. This should only occur when the vehicle is in motion.Troubleshooting:Check the fuel pressure in order to ensure that a fuel system restriction is not the cause of the problem when the vehicle is not moving.Test Step 1. Perform the following diagnostic procedure: "Vehicle Speed and Speedometer Circuit - Test"Results:
OK - STOP