HOUSING AS-REGULATOR 3550411 - Caterpillar

Illustration 1 g00501598
Schematic of the Engine Speed Sensor This diagnostic code is recorded when VIMS reads the signal from the sensor and the frequency of the signal or pulse of the signal is not within an expected range. The sensor sends a PWM signal to the VIMS module. The possible causes of this diagnostic code are listed here:
The sensor has failed.
Intermittent or poor connections
The VIMS interface module has failed. This is unlikely.Note: The following diagnostic code procedure can create other related diagnostic codes. Perform the following procedure. Reconnect all harnesses. Then clear all the related diagnostic codes.
CHECK THE SENSOR.
Turn the disconnect switch and the key start switch to the ON position.
Ensure that the diagnostic code is active.
Disconnect the sensor from the machine harness.Expected Results: The diagnostic code is NO longer active.Results:
YES - The diagnostic code is NO longer active. The sensor is faulty. Replace the sensor. Verify that the new sensor corrected this diagnostic code. The diagnostic code should NOT be active. STOP.
NO - The diagnostic code remains active. The sensor is not the cause of the diagnostic code. Proceed to 2.
CHECK FOR A SHORT IN THE HARNESS.
The sensor remains disconnected from the machine harness.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connector from the VIMS interface module.
At the machine harness connector for the VIMS interface module, measure the resistance between the signal contact 29 (wire 450-YL) to all other contacts.Expected Results: Each resistance measurement should be greater than 5000 ohms.Results:
YES - Each resistance measurement does measure greater than 5000 ohms. The harness is correct. It is unlikely that the VIMS interface module has failed. Exit this procedure and perform this diagnostic code procedure again. If the cause of the diagnostic code is not found, replace the VIMS interface module. See Testing and Adjusting, " Module - Replace". STOP.
NO - The resistance measurement does not measure greater than 5000 ohms for all measurements. The machine harness is faulty. There is a short in the machine harness. The short is between the signal circuit (wire 450-YL) and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness. STOP.