BRAKE GP-SERVICE 9D3480 - Caterpillar

Illustration 1 g02713956
Connections of the Transmission Hydrstatic Loop "B" Pressure SensorThis diagnostic code is related to the transmission hydrostatic loop "B" pressure sensor. An FMI 03 means the Transmission ECM has determined the signal output voltage of the pressure sensor is above normal.The sensor output is a Pulse Width Modulated (PWM) frequency signal at 500Hz ( 100Hz). The signal duty cycle changes as the sensor pressure changes.
Illustration 2 g02739817
Bulkhead Connectors (1) Loop B Sensor (2) Flushing Oil Temp Sensor (3 ) Loop A SensorThis sensor is internal to the transmission. The sensor is part of the sensor/pigtail/bulkhead assembly (1). There are external bulkhead connectors at the transmission case as shown in Illustration 2.This troubleshooting procedure is initially conducted at the external bulkhead connector on the transmission. The bulkhead connector stays in the plate and is held in place via a snap ring.The bulkhead is one end of the pigtail that connects to the sensor. The pigtail is potted to the pressure sensor and cannot be detached without damaging the sensor.Possible causes for this diagnostic code are:
The sensor power supply may have failed.
The sensor may have failed.
The sensor output signal may be shorted to a voltage source.
The sensor output signal circuit may be open.
The Transmission ECM may have failed, but 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 now, but clear those codes after the original diagnostic code has been corrected. Test Step 1. VERIFY THE +8 VDC SUPPLY
Turn the key start switch and the disconnect switch to the ON position. Do not start the engine.
Do not disconnect any of the machine harness connectors at this time.
At the external bulkhead connector for the Loop B Pressure Sensor (1), insert the multimeter probes at contact 1 (J850-WH), the sensor power supply,