PLATE-COUPLING 4177933 - Caterpillar

Illustration 1 g02142780
Connections of the Power Train Speed Range Control Position Sensor
This diagnostic code is associated with the Power Train Speed Range Control Position Sensor. The Thumbwheel is located on the left Speed / Direction Handle. The FMI 08 diagnostic means that the ECM has determined that the signal is outside the expected range.The sensor sends a 0.0 VDC to 5.0 VDC PWM signal to the ECM in order to indicate the position of the thumbwheel. The duty cycle of the signal will determine the amplitude of the voltage. A 20% duty cycle will result in a voltage of approximately 1.0 VDC on the signal circuit. An 80% duty cycle will result in a voltage of approximately 4.0 VDC. A 50% duty cycle will result in a voltage of approximately 2.5 VDC.When the Speed Control Thumbwheel is moved to the full left position in order to decrease the speed, the sensor PWM duty cycle input to the ECM is 20 5%. When the Speed Control Thumbwheel is moved to the full right position in order to increase the speed, the sensor PWM duty cycle input to the ECM is 80 5%. When the Speed Control Thumbwheel is in the center position, the sensor PWM duty cycle input to the ECM is approximately 50%. The possible causes of this diagnostic code are listed below:
The sensor has failed.
Intermittent connections or poor connections
Mechanical devices are loose.
The ECM has failed. An ECM failure is unlikely.Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean. Verify that all connections in the circuit are secure. Verify that all connections in the circuit are in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.
Table 1
Signal for Positions of the Thumbwheel Sensor
Position Percentage of duty cycle for the Thumbwheel at J2-42 wire (C584-WH(White))
Right
(Upshift) 80 5 %
Center 50 5 %
Left
(Downshift) 20 5 % Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 2500 - FMI 08 is active before performing this procedure.Note: Use a digital multimeter for the measurements in this procedure. System Response:A level 2 warning will be generated. The functionality is lost. The ECM cannot increase or decrease the desired speed. Other functions can aid in reducing machine speed such as the brake pedal.Test Step 1. Check for power at the sensor
Turn the disconnect switch and the key switch to the ON position. Do NOT start the engine.
Do not disconnect the harness connector from the sensor.
At the back of the