RING-SNAP 4530712 - Caterpillar

Illustration 1 g02359871
Schematic of the direction selector #2 position sensor #1
The CID 3377 diagnostic code is associated with direction selector #2 position sensor #1. The signal receives power from the transmission ECM. The position sensor sends a PWM input signal to the transmission ECM. The duty cycle of the signal should be 80% to 95% in the forward position and 5% to 20% in the reverse position. In neutral position the duty cycle should be within 40% to 60%. The position sensor is a PWM sensor that operates at a frequency of approximately 500 40 Hz.The FMI 04 diagnostic code is activated when the ECM reads the input signal from the sensor and the voltage is below the acceptable range. The possible causes of this diagnostic code are listed below:
The signal circuit is shorted to a ground source.
The sensor has failed.
The ECM has failed. The ECM failing is unlikely. System Response:
A level 2 warning will be generated.
All functions that control the pitch of the blade are disabled.
The "Limp Home" option is still available.Note: Ensure that the CID 3377 FMI 04 diagnostic code is active. This procedure can cause new diagnostic codes to be recorded. Ignore these created diagnostic codes. When the procedure is completed, clear the created diagnostic codes.Test Step 1. CHECK THE SENSOR
Turn the disconnect switch and the key start switch to the ON position. Do not start the engine.
Disconnect the machine harness connector from the sensor. Observe the status of the active FMI 04 diagnostic code. Expected Result:The FMI 04 diagnostic code remains active when the harness connector is disconnected. An FMI 03 diagnostic code has not been activated by the ECM.Results:
OK - The FMI 04 diagnostic code remains active when the harness connector is disconnected. The sensor is not causing the problem. Proceed to Test Step 2.
NOT OK - The FMI 04 diagnostic code is no longer active when the harness connector is disconnected from the sensor. An FMI 03 diagnostic code is activated when the harness connector is disconnected. The machine harness and the ECM are operating correctly.Repair: The sensor is causing the problem. There is an internal short to ground in the sensor group. Replace the sensor group. After the sensor group is replaced, verify that the operation of the new sensor group has corrected the problem before operating the machine.STOPTest Step 2. CHECK THE SIGNAL CIRCUIT FOR A SHORT TO GROUND
The machine harness connector remains disconnected from the sensor.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the J1 and J2 machine harness connectors from the ECM.
At the J2 machine harness connector for the ECM, measure the resistance from contact J2-40 wire (N913-YL(Yellow)) to a clean source of frame ground. Measure the resistance from contact J2-40 wire (N913-YL(Yellow)) to all of the other J1 and J2 contacts that are used for the ECM. Expected Result:Each resistance measurement is greater than 5000 ohms.Results:
OK - Each resistance measurement is greater than 5000 ohms. The circuit is correct. Proceed to Test Step