PRESSURE CONTROL VALVE GROUP 3P4489 - Caterpillar

Illustration 1 g02712039
Connections of the Transmission Synchronizer # 3 Position SensorThis diagnostic code is associated with the transmission synchronizer #3 position sensor. The FMI 08 means that the ECM has determined that that the signal frequency or the signal pulse width is not within the expected range.The sensor is an analog PWM sensor that has an operating duty cycle of 10% at minimum sensed position to 90% at maximum sensed position. The sensor is used to read the position of the synchronizer #3 fork of the transmission. The position of the synchronizer defines whether the synchronizer is engaged, disengaged or somewhere in-between.Sensor output, versus synchronizer position, is dependent on a particular transmission design.The possible causes of this diagnostic code are listed below:
Missing 8V supply and/or ground
The sensor has failed.
Intermittent connections, or poor connections. Missing 8V supply and/or ground
Mechanical devices are loose
The Transmission ECM has failed. This condition is unlikely.This code would not be shown if there is an existing 8V supply diagnostic code.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 CID 2819 FMI 08 diagnostic code is active before performing this procedure.Note: Use a digital multimeter for the measurements in this procedure.Test Step 1. CHECK THE VOLTAGE AT THE SENSOR
Turn the key start switch and the disconnect switch to the ON position. Do not start the engine.
Do not disconnect the harness connector from the sensor.
At the back of the harness connector for the sensor, insert a multimeter probe at contact 1 J850-WH, the sensor power supply and contact 2 (J764-BR), the sensor GROUND.
Measure the voltage from contact 1 to contact 2.Expected Result:The voltage is 8 0.5 VDC.Results:
OK - The voltage is 8 0.5 VDC. Proceed to Test Step 2.
NOT OK - The voltage is NOT 8 0.5 VDC. The voltage is not correct. There is an open, or loose, connection in the circuit.Repair: Repair, or replace, the machine harness as needed.Poor connections are often the cause of a problem in electrical circuits. Inspect the harness connectors involved in the circuit. Verify that all of the connections in the circuit are clean, secure, and in good condition. To verify that the problem was corrected, and that the CID 2819 - FMI 08 diagnostic code is no longer active, Go to Test Step 4.Test Step 2. CHECK SIGNAL CIRCUIT FOR AN OPEN
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connectors and the ECM harness connectors from the sensor and the ECM.
At the sensor connector, connect a jumper wire from the signal wire X955-GN to a known ground.
At the ECM connector, measure the resistance of signal wire X955-GN at ECM.Expected Result:The resistance is less than 5 ohms.Results:
OK - The resistance is less than 5 ohms. Proceed to Test Step 3.
NOT OK - The resistance is greater than 5000 ohms. The signal circuit in the harness is open.Repair: